Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams
The structural-phase states, microhardness, and tribological properties of hypoeutectic silumin after electron-beam treatment are studied by the methods of contemporary physical materials science. The object of the study is hypoeutectic АК10М2Н-type silumin containing 87.88 wt.% of Al and 11.1 wt.%...
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| Дата: | 2019 |
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Інститут металофізики ім. Г.В. Курдюмова НАН України
2019
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| Цитувати: | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams / Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Е. Gromov, V.D. Sarychev, A.P. Semin // Progress in Physics of Metals. — 2019. — Vol. 20, No 3. — P. 447-484. — Bibliog.: 59 titles. — eng. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859658386442813440 |
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| author | Ivanov, Yu.F. Zagulyaev, D.V. Nevskii, S.A. Gromov, V.Е. Sarychev, V.D. Semin, A.P. |
| author_facet | Ivanov, Yu.F. Zagulyaev, D.V. Nevskii, S.A. Gromov, V.Е. Sarychev, V.D. Semin, A.P. |
| citation_txt | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams / Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Е. Gromov, V.D. Sarychev, A.P. Semin // Progress in Physics of Metals. — 2019. — Vol. 20, No 3. — P. 447-484. — Bibliog.: 59 titles. — eng. |
| collection | DSpace DC |
| container_title | Успехи физики металлов |
| description | The structural-phase states, microhardness, and tribological properties of hypoeutectic silumin after electron-beam treatment are studied by the methods of contemporary physical materials science. The object of the study is hypoeutectic АК10М2Н-type silumin containing 87.88 wt.% of Al and 11.1 wt.% of Si as the base components.
Методами сучасного фізичного матеріалознавства досліджено структурно-фазові стани, мікротвердість і трибологічні властивості доевтектичного силуміну після електронно-пучкового оброблення. Об єктом дослідження був доевтектичний силумін марки АК10М2Н із вмістом 87,88 ваг.% Al й 11,1 ваг.% Si як головних компонентів.
Методами современного физического материаловедения исследованы структурнофазовые состояния, микротв рдость и трибологические свойства доэвтектического силумина после электронно-пучковой обработки. Объектом исследования являлся доэвтектический силумин марки АК10М2Н с содержанием 87,88 вес.% Al и 11,1 вес.% Si как главных компонентов.
|
| first_indexed | 2025-11-30T09:55:08Z |
| format | Article |
| fulltext |
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 447
© Yu.F. IVANOV, D.V. ZAGULYAEV, S.A. NEVSKII,
V.Å. GROMOV, V.D. SARYCHEV, A.P. SEMIN, 2019
https://doi.org/10.15407/ufm.20.03.447
Yu.F. IVANOV 1,2, D.V. ZAGULYAEV 3, S.A. NEVSKII 3,
V.Е. GROMOV 3, V.D. SARYCHEV 3, and A.P. SEMIN 3
1 Institute of High-Current Electronics, SB RAS,
2/3 Akademicheskiy Ave., 634055 Tomsk, Russia
2 National Research Tomsk Polytechnic University,
2/3 Akademicheskiy Ave., 634055 Tomsk, Russia
3 Siberian State Industrial University,
42 Kirov Str., 654007 Novokuznetsk, Russia
MICROSTRUCTURE AND PROPERTIES
OF HYPOEUTECTIC SILUMIN TREATED
BY HIGH-CURRENT PULSED ELECTRON BEAMS
The structural-phase states, microhardness, and tribological properties of hypo-
eutectic silumin after electron-beam treatment are studied by the methods of con-
temporary physical materials science. The object of the study is hypoeutectic
ÀÊ10Ì2Í-type silumin containing 87.88 wt.% of Al and 11.1 wt.% of Si as the
base components. The silumin surface is subjected to electron-beam treatment in six
various regimes distinct in the density of electron-beam energy. The microhardness
measurements of the modified silumin-surface layers enabled to determine three
optimal impact regimes (with electron-beam energy densities of 25, 30, and 35 J/cm2),
when the modified-layer microhardness exceeds that for the cast silumin. The
obtained parameters are as follow: 0.86 ± 0.41 GPa for the cast state;
0.93 ± 0.52 GPa for 25 J/cm2; 0.97 ± 0.071 GPa for 30 J/cm2; 0.96 ± 0.103 GPa for
35 J/cm2. As found, the electron-beam treatment with the optimal parameters re-
sults in the formation of the surface whose mechanical and tribological characteris-
tics sufficiently exceed corresponding values for the cast state of silumin. The
atomic-force microscopy data correlate with the results on microhardness. The sam-
ples treated in the presented regimes are characterised with the fine-grained cellu-
lar structure and have the least roughness of the treated layer (of 17–33 nm) and
substrate (of 45–57 nm) as compared to other regimes. As revealed, in the treated
layer, the fine-grained, graded, and cellular structure is formed, and it transforms
into the mixed-type structure when deepening away from the surface of treatment.
Depending on the parameters of electron-beam treatment, the thickness of homog-
enized layer varies and reaches the maximum values of 100 μm at the energy den-
sity of 35 J/cm2. As detected, the modified layer is free from intermetallides and
consists of the nanocrystalline structure of cellular crystallization. As assumed,
448 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
1. Introduction
One of the most promising methods of surface hardening of materials,
demonstrating its high effectiveness, is electron-beam treatment [1–5].
It ensures the ultrahigh rates of heating (up to 106 K/s) of surface
layer at a present temperature and the cooling of surface layer at the
expense of heat removal in the bulk of the material at the rates of
104–109 K/s with the result formation of nonequilibrium submicro- and
nanocrystalline structural-phase states [1].
The type of treatment being considered has wide possibilities of the
supplied energy checking, the small coefficients of energy reflection,
the high concentration of energy in the volume unite of the material [2].
The electron-beam treatment has a number of advantages over other
methods of surface modification. In comparison with the powerful ion
beams, the electron-beam treatment has a substantially higher efficien-
cy in pulse-frequency regime at smaller accelerating voltages and needs
no special radiation protection. The high-energy efficiency, the high
homogeneity of energy density in the streamwise section, the good sus-
ceptibility of pulses, and their high pulse-repetition rate give a number
of advantages over the pulsed flow of low temperature plasma [3–5].
The main advantage of the electron beam treatment (EBT) is the
combination of actually complete absorption of electron energy with the
possibility of variation of depth of electrons’ penetration in the mate-
rial and, respectively, the dynamics of thermal fields and the parame-
ters of stress wave.
To estimate the modern state of the scientific problem, let us con-
sider some papers, in which the problem of electron-beam effect on dif-
ferent materials as the method of their hardening was discussed.
The authors of the paper [6] investigated the mechanical properties
of YG10X carbide irradiated by high-current pulsed electron beam with
the constant energy density of 6 J/cm2 and different number of pulses.
Vickers hardness served as the described mechanical characteristic more
completely reflecting the state of the material after the electron-beam
radiation. For the untreated sample, the microhardness amounted to
≈2165 HV on the average in different regimes of loading. As established
these two factors are responsible for the increased mechanical and tribological char-
acteristics of the modified layer. The formation mechanism for structure of cellular
and columnar crystallization consisting in the initiation of thermocapillary instabil-
ity over the ‘evaporated substance/liquid phase’ interface is offered. The mathemat-
ical model of the thermal effect of electron beam on the silumin-surface layers is
developed.
Keywords: physical nature, mathematical model, structure, properties, hypoeutectic
silumin, electron beam treatment, phase composition.
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 449
in the course of the study, the irradiation by high-current pulsed elec-
tron beam resulted in 1.5–2-fold increase in microhardness of the mate-
rial. The tribological studies showed that the friction coefficient after
10 pulses decreased 3-fold from the initial state. The improved tribo-
logical properties were connected, mainly, with the effect of hardening
of composite microstructure. In Ref. [7], it was established that not
only the increase in the number of pulses of treatment but also the
change in the parameter of electron beam current could lead to the in-
crease in microhardness. Microhardness of Ti–47Al–2Cr–2Nb (here and
hereinafter, in wt.%) alloy increases with the increase in the beam cur-
rent from 4.5 mA to 8.5 mA and amounts to 330.45 HV at beam current
from 4.5 mA and 368.98 HV for the sample with beam current 8.5 mA,
it is by 11.66% higher.
The studies of electron beam treatment are carried out using not
only the volume materials but also various coatings. The electron-beam
effect various energy at 20 pulses on the nanohardness and roughness
of TiN coating [8] was studied. It was found that nanohardness de-
creased to ≈25 GPa at energy density of 3 J/cm2, ≈24 GPa at density of
irradiation energy of 5 J/cm2, as compared to the initial value of
≈26 GPa. With the further increase in the density of irradiation energy
to 8 J/cm2, the nanohardness of the irradiated coating TiN decreases
abruptly to ≈10 GPa. It is possible that it is connected with the appear-
ance and distribution of the surface cracks on irradiation. On the con-
trary, the roughness of the coating increases with the density growth of
electron beam energy. It is detected that interphase adhesion is essen-
tially higher for the irradiated sample with 5 J/cm2 than for the sam-
ples irradiated by energy of 3 J/cm2 and 8 J/cm2. Ti–5Al–4V alloy [9]
may be used as the substrate being irradiated. TiN/TiO2 coatings were
applied to the substrate; then, the system was subjected to treatment by
pulsed electron beam. It was found that electron-beam treatment re-
sulted in the decrease in the microhardness value of the material with
respect to the initial state from 7 to 6 GPa, the friction coefficient
value decreased and, on the contrary, the roughness of the surface in-
creased from 8 nm to 25 nm.
The latest researches carried out when using the samples of Al–15Si
hypereutectic alloy showed that the treatment by high-current pulsed
electron beam increased the tensile strength of the treated alloy by
41.4% from 138.8 MPa (for the initial sample) to 196.2 MPa for the
modified sample. Thus, the treatment by high-current pulsed electron
beam is the universal method for the improvement of the mechanical
properties of hypereutectic alloys of Al–Si system [10].
The main scientific trend of the study of electron-beam treatment
effect is the way of precision modification of structural-phase states and,
therefore, the surface properties and surface layers of metallic materials.
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
450 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
By methods of scanning electron microscopy, the samples of Ti–36-
Nb–2Ta–3Zr–0.35O alloy [11] after the electron-beam treatment were
studied. It is found that, in the initial state, the alloy has a sufficient
quantity of pores, while the treated samples were characterized by low
porosity. The x-ray diffraction patterns show that the samples treated
by the intense electron beam have β-phase as the base one. The depth of
melting of the surface layers of the material depends on the density of
beam energy and rate of treatment. The effect of scanning rate by elec-
tron beam on the structure of Al–3Ti–1Sc alloys was described in Ref.
[12]. It was detected that the rate of electron-beam treatment played the
key role in the determination of phase composition and the development
of microstructure in the alloy: the increase in the treatment rate and
beam energy resulted in the increase in the area and depth of the sur-
face remelting. As the substrate from Al–3Ti–1Sc was cast in the low-
cooling conditions and Ti and Sc concentration increased substantially
in the equilibrium solubility limit, a large number of the initial inter-
metallic phases were present in the microstructure; however, after the
electron-beam treatment, the initial intermetallic phases were not ob-
served. With the increase in the scanning rate, higher concentrations of
Sc and Ti in the substrate than in the initial state were observed as well.
The performed studies on the high-current electron beam effect on
the structure and properties of the commercial magnesium alloys of
AZ91HP-type showed that the formation of the crater defects takes
place on the irradiation, but with the increase in the number of treat-
ment pulses, the tendency to the decrease in the defect and their disap-
pearance [13] was observed. The formation mechanisms of defects under
the effect of high-current pulsed electron beams were described in the
earlier papers [14, 15]. The surface layer is melted to ≈8–10 μm depth
where Mg17Al12 phase is practically absent under the effect of the pulsed
treatment; the results of x-ray spectroscopic analysis support this phe-
nomenon. It is also identified that, after electron-beam treatment, the
diffraction peaks are displaced to the wide-angle side that can be in-
dicative of the decrease in the lattice parameter of α(Mg)-phase with the
increase in Al concentration.
In the review [16], the results of the experimental investigations
into the EBT effect on the formation of properties, structure and phase
composition of silumin surface layers are generalized.
Nowadays, the electron-beam effect on the materials is a compli-
cated complex of the phenomena including the heating, melting, convec-
tive flows in the liquid layer, vaporization of substance, the consequent
crystallization, and, as a result, the formation of the ordered structures
of surface layers [17–22]. The columnar crystallization structure be-
longs to these structures. As the electron-microscopy investigations
show [21, 22], the transverse dimension of these structures is of
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 451
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
≈0.1 nm–1 μm. The mechanism of their initiation on the surface of the
melt can be connected with the development of thermocapillary instabil-
ity [23] that is formed due to the action of thermocapillary forces along
the surface of the melt. They arise because of the dependence of the
surface tension on temperature and the presence of the stable gradient
of temperature. Theoretical study of the instability of the molten layers
of the materials under the action of laser radiation was performed in
Refs. [24–30]. These papers show that the spectrum of surface pertur-
bations of the molten layer of the viscous incompressible fluid at the
initial stage of development is described by the algebraic dispersion
equation connecting the frequency and module of wave vector. As a
rule, the dispersion equation is lengthy, and it depends on many param-
eters; therefore, its numerical solution or finding of neutral curve is
frequently used. It is the important information for the determination
of the number of parameters at which the instability occurs. By means
of the approach, the wave number is found, at which the rate of pertur-
bation growth transits via naught, i.e. the critical wave number. It
proved to be not enough because the wave numbers at which the maxi-
mum of growth rate arises play the important role. Therefore, the ap-
proximate formulae for obtaining of the dependence of the growth rate
on the magnitude of wave number vector is necessary to be used for the
obtaining of the physical consequences required for the analysis of con-
ditions of the ordered structure formation of the surface layers. The
approach based on the search for growth rate maximum was success-
fully used in Ref. [31] for the Kelvin–Helmholtz instability. In this
paper, the dispersion equation that enables to perform the analytical
parameterization and to obtain the important physical consequences
[31], for example, the presence of two maximums, was derived for the
short-wave approximation.
As follows from the papers discussed above, it was established that
the application of electron beams for the treatment of metal surface
resulted in change in structural-phase composition of surface layers and
it, in its turn, led to the increase in the mechanical characteristics in-
cluding wear resistance, microhardness and corrosion resistance as well.
In this connection, the goal of the study consists in the following.
Firstly, the analysis of the experimental data of the change in the me-
chanical and tribological characteristics, structural-phase transforma-
tions in silumin under electron-beam treatment. Secondly, theoretical
study of the mechanisms and the development of the mathematical mod-
el of the ordered structure formation in the surface layers of silumin
under electron-beam treatment on the basis of the concepts of thermo-
capillary instability of the molten layers.
452 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
2. Object of the Study and Research Methods
The hypoeutectic alloy of silumin ÀÊ10Ì2Í (the grading refers to tech-
nical state standard GOST used in Russia) was used as test-material.
The chemical composition of the material being tested was determined
by the methods of x-ray spectrum analysis. As a result of the analysis,
it was established that the base elements of its chemical composition are
Al (87.88%) and Si (11.1%) diluted with balance admixtures of Cu, Ni,
Mg, and Cr. The alloy of aluminium with silicon under consideration
finds wide application in many branches of industry, in particular, in
automobile construction in the manufacture of pistons of internal com-
bustion engines.
The test samples had the dimensions of 20 × 20 × 10 mm3 and were
oriented perpendicular to the electron beam. The surface modification
was done using the plant ‘SOLO’ of the Institute of High Current Elec-
tronics at the SB RAS [32, 33].
The plant has the following main advantages over the earlier pulsed
electron sources with plasma cathode: the high energy density in combi-
nation with a low accelerating voltage; the higher energy efficiency; the
high range of parameter regulation; the good repeatability of pulses;
the minimum time for preparation; the long service life [34].
The ÀÊ10Ì2Í silumin samples were irradiated by the intense pulsed
electron beam in six regimes being distinguished by the energy density
of electron beam (Table 1) and having the following identical parame-
ters: the energy of accelerated electrons of 17 keV; the duration of elec-
tron beam pulse of 150 μs; the number of pulses — 3, the pulse repeti-
tion rate of 0.3 s−1; the pressure of residual gas (argon) in the working
chamber of 2 ⋅ 10−2 Pa.
The metallographic analysis of structural changes was performed
using optical microscope Olympus GX-51. For structural determination
of the material by means of metallography, the samples were cut,
ground, polished and etched. For the optical contrast, the samples were
etched chemically by the solution containing 72% H2O, 21% HF, and
7% HCl.
One of the most precision and sensitive methods — the measure-
ment of microhardness — was used in the research as the characteristic
of the mechanical properties of the surface layers. It is differences prior
and after the treatment can serve as strain-hardening exponent of the
modified surface layers of metals and alloys. The microhardness measu-
Table 1. Regimes of silumin irradiation with high-intense electron beam
No. of regime 1 2 3 4 5 6
Energy density Es, J/cm2 10 15 20 25 30 35
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 453
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
re ments were done using the microhardness tester HVS-1000 by Vickers
method [35]. The stable load for six regimes of treatment amounted to
0.05 N. The time of load application and load maintaining was of 10 s,
and that of test load removal was of 5 s.
The tribological tests were performed according to the ‘pin-on-disc’
scheme at tribometer CSEM CH 2000 (at load P = 2 N and sliding veloc-
ity V = 10 mm/s; the counterbody diameter from ball bearing steel
of 6 mm) in accordance with ASTM G99. The distance of friction was
S = 20 m and radius of wear track r = 2 mm.
The investigation into the modified zone of silumin samples sub-
jected to the electron-beam treatment were performed using atomic-
force microscope NT-MDT Solver ‘NEXT’. The samples had the dimen-
sions of 5 × 10 × 10 mm3, and they passed the identical algorithm of
preparation as those for microindentation and metallography.
The program Image Analysis 3.5 [36] was used for the processing of
the obtained atomic-force images. By means of the program, the meas-
urements of pores in the coating were made, the transition layer was
studied and roughness of samples was determined as well.
The roughness estimation was done according to Russian Standard
GOST 2789-73 using the function Standard statistics, where the stand-
ard statistical parameters characterizing the initial function Z (xj, yj)
(the recorded signal of feedback) as a random quantity Z [37] were rep-
resented. The main parameter for roughness estimate is the value
Roughness average — the arithmetic mean value of roughness that
reads as 1
1 1( ) | |y x
N N
a x y j i ijR N N Z−
= == ∑ ∑ , where Nx (Ny) is the quantity of
points with x (y) coordinates, and Zij is the value of Z coordinate.
The analysis of the elemental and phase compositions, defect struc-
ture of the modified layer was done by the methods of scanning electron
microscopy (SEM) using the plants SEM-515 Philips equipped with
microanalyzer EDAX ECON IV.
The determination of the chemical composition was performed by
means of energy-dispersion detector of micro x-ray spectroscopic analy-
sis INCAx-act. The elemental analysis of some phases was carried out by
the method of electron-probe microanalysis that enabled to study the
presence, content and distribution of the elements of Periodic Table.
The phase composition of the modified layers that is the qualitative
and quantitative characteristics of the presence of different phases in
them, their content, dispersion, structure and chemical composition
were determined by the method of x-ray phase analysis (diffractometer
XRD-7000 s, Shimadzu, Japan) in addition to the electron-diffraction
microscopy.
The defect structure of the samples was analysed by the methods of
transmission electron-diffraction microscopy of thin foils (plant JEM-
454 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
2100 F, JEOL) [38–40]. The images of fine structure of the material
were used for the classification of the morphological indications of the
structure [41].
The foils for the investigation into the structural phase state of the
material by the methods of transmission electron-diffraction microscopy
were prepared by ion thinning of ≈100 μm thick plates cut out the sam-
ple by the electrical spark method. The regime of cutting out was se-
lected in such a way that it produced no additional deformation, and,
consequently, it had no effects on the sample structure.
The plates cut out in such a way were thinned by ion etching meth-
od (plant Ion Slicer EM-09100 IS). The distinctive feature of the plant
is that it requires no preparation of the disc thinned in the centre. The
preliminary preparation of samples for Ion Slicer consists only in the
manufacture of parallelepiped to the dimensions of 2.8 × 0.5 × 0.1 mm
that is closed from the thin wide end by the special protective tape and
is thinned by the beam of argon ions. The beam energy is less than 8 kV,
and the angle of incidence can be varied from 0° to 6° with respect to
the largest face of the sample. It enables to minimize the radiation dam-
ages and, thereby, to conserve the initial structure and phase composi-
tion of the sample and, after it, to study them by the methods of elec-
tron microscopy.
3. Results and Discussions
3.1. Changes of Mechanical and Tribological
Properties of Silumin after EBT
The dependence of change in microhardness of silumin surface on the
energy density of electron beam is shown in Fig. 1. The increase of the
energy density results in the monotonous increase in the microhardness
value on the surface of irradiation. The maximum microhardness value
is observed at energy density of electron beam of 30 J/cm2. The further
increase of the energy density up to 35 J/cm2 results in the insignifi-
cant decrease of the microhardness value.
As the maximum values of surface microhardness are observed for
values of 25, 30, and 35 J/cm2, the studies of microhardness profile
distribution depending on the distance to the surface of irradiation us-
ing the transverse metallographic sections were carried out. As the met-
al contains the grains of aluminium and eutectic, the microhardness
measurements were carried out separately in the grain (Fig. 2, c) and in
eutectic (Fig. 2, b).
It is determined that the microhardness values both in grains and in
eutectic of the modified samples increase as the sprayed layer is ap-
proached (Fig. 3). It is discovered that irrespective of the treatment
regimens the microhardness of samples in the zone subjected to irradia-
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 455
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
tion is larger than at 90 and 70 μm
distances from the sample edge.
The analysis of dependences gives
grounds for making a conclusion
that microhardness of silumin in
eutectic is larger than in grains.
As seen in Fig. 3, d, microhard-
ness value decreases as the bulk of
the material is being approached and at 90 μm depth (0.93 ± 0.52 GPa
for 25 J/cm2; 0.97 ± 0.071 GPa for 30 J/cm2; 0.96 ± 0.103 GPa for
35 J/cm2) irrespective of the treatment regime.
According to the results of the investigation into the effect of elec-
tron-beam treatment on microhardness of silumin surface layers, the
conclusion can be made that the optimal parameters of treatment which
permit a 2-fold increase in microhardness are the regimes with energy
density of 25, 30, 35 J/cm2.
Having analysed the changes of microhardness of the samples being
tested, the parameter of plasticity (Fig. 4) can be calculated.
As known, the characteristic of plasticity determined by the Vickers
method can be defined in the form as follows [42]: δ = 1 − 1.1/(1 − ν − 2ν2)
HV/E, where HV is a microhardness magnitude, E is the Young modu-
lus, ν is the Poisson’s ratio of the material being studied.
The analysis of dependences of plasticity parameter δ on the dis-
tance to the surface of treatment shows that, in the zone of the modified
Fig. 1. Dependence of change of microhard-
ness on energy density of electron beam
Fig. 2. Microstruc-
ture of transverse
metallographic sec-
tion of silumin ir-
radiated by intense
pul sed electron beam
(Es = 35 J/cm2): a —
silumin structure
near the irradiation
surface; b — eutec-
tic at 70 μm distance
from the surface;
c — indentation in
aluminium grain at
70 μm distance
456 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
layer, it has the minimum values irrespective of the treatment regime.
The movement deep into the material results in the non-monotonous
increase in the plasticity parameter. It should be noted that the plastic-
ity parameter has the minimum values in the eutectic in the treatment
regime of 35 J/cm2. Moreover, the plasticity parameter value is larger
in grains than in eutectic irrespective of the treatment regimes.
The tribological properties of modified silumin are characterized by
the wear intensity (the parameter inverse to wear resistance) and fric-
tion coefficient. Simultaneously with the microhardness increase, the
decrease in the friction coefficient and wear intensity is observed in the
irradiated samples.
At an irradiation parameter Es = 35 J/cm2, the friction coefficient
varies relative to as-received sample (μ = 0.45 relative to 0.47). Differ-
ent data are obtained on irradiation with energy density of electron
beam Es = 15 J/cm2: the wear coefficient relative to as-received sample
decreased by 21% and amounted to 0.37.
Fig. 3. Dependences of microhardness value distribution in the grains and in the
eutectic of silumin on the distance from the modified surface (a — 25 J/cm2; b —
30 J/cm2; c — 35 J/cm2; d — on the average in the material)
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
The wear intensity of irradiated sample decreases many times and is
practically independent on triboloading parameters (I = 2.7 ⋅ 10−3 relative
to 0.78 ⋅ 10−3 mm3/(N ⋅ m) at Es = 35 J/cm2 and 0.93 ⋅ 10−3 mm3/(N ⋅ m) at
Es = 15 J/cm2). In our opinion, the reason for it should be the develop-
ment of seizure and pitting processes of hardening particles character-
istic of Al-alloys and its suppression due to irradiation-caused modifica-
tion of the surface layer structure.
The time of running for as-received sample, the production of fric-
tion coefficient value at the set regime of change, is much longer (in the
terms of friction path it is not less than 0.003 km). On the other hand,
the friction coefficient value itself for as-received samples and after ir-
radiation (at Es = 35 J/cm2) is practically identical. In the authors’
opinion, the primary reason of it is the decrease in the slip velocity that
due to the decrease in the friction heating should decrease in the inten-
sity of the development of seizure and pitting processes of the harden-
ing particles.
Fig. 4. Dependence of plasticity parameter in the grains and eutectic on the distance
from the modified surface of silumin samples subjected to electron beam treatment
(a — 25 J/cm2; b — 30 J/cm2; c — 35 J/cm2; d — on overage in the material)
458 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
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For the comparison, the graph
of change in the wear coefficient
of silumin irradiated by the small-
er dose (Es = 15 J/cm2), for which
the decreased μ value corresponds
to the decreased wear intensity as compared to the unirradiated mate-
rial (compare I = 0.93 ⋅ 10−3 mm3/(N ⋅ m) relative to 2.7 × 10−3 mm3/(N ⋅ m),
is shown in Fig. 5.
The additional information about the causes of the regularities be-
ing observed was obtained from the analysis of tribotracks of the tested
samples. In the case of the irradiated sample (Es = 35 J/cm2), the tri-
botrack width amounted to 500 μm and its depth was less than 12.1 μm.
The measurements of the indentation area showed that the irradiation
resulted in decrease of the indentation area from 8.52 μm3 (cast state)
to 2.47 μm2 (Es = 35 J/cm2). For the smaller dose of electron-beam treat-
ment (Es = 15 J/cm2), the investigation area amounted to 2.95 μm2, and
the maximum depth was less than 14.3 μm.
In addition to it, the studies of friction track surfaces were per-
formed. It is seen that the friction surface of the unirradiated sample
Fig. 6. Optical images of friction tracks (a) and counterbody (b)
for the cast-state silumin and after irradiation with an intense
pulsed electron beam
Fig. 5. Dependence of friction coeffi-
cient μ on the time of tribological tests
in the cast state silumin and after irra-
diation with an intense electron beam
(15 J/cm2)
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
looks less homogeneous and a large number of dark regions testifies in
favour of the development of seizure and pitting processes. These phe-
nomena are displayed in the irradiated sample of silumin to a far lesser
extent. The analysis of counterbody surfaces shows that, in tribotests,
the processes of transfer of wear products develop; the counterbody for
the unirradiated sample contains a large number of dark regions being
the consequence of the wear product sticking (Fig. 6, b). The process is
displayed in the far lesser extent on the surface of counterbody.
It follows from the analysis of wear track profiles of silumin that,
in tribotechnical tests of the cast material, the wear tracks are formed,
they have the essentially larger dimensions and a large drop of track
depth.
It is evident that the substantial increase in microhardness and tri-
botechnical properties of silumin mentioned above is caused by the mod-
ification of the elemental and phase composition as well as the state of
defect substructure of silumin surface layer initiated by high-speed
thermal treatment taking place in the irradiation of the material by
intense pulsed electron beam [43–48].
3.2. Atomic-Force Microscopy of Silumin Subjected to EBT
The image of the initial sample profile obtained by the atomic-force mi-
croscopy is shown in Fig. 7. The presence of the dendritic granular
structure and intergranular eutectic is seen. The grain boundaries have
the inclusions of intermetallides consisting mostly of copper, manga-
nese and nickel, which were revealed by the methods of scanning elec-
tron microscopy. The roughness of the silumin initial sample amounts
to ≈50 nm.
The images of the sample profiles treated by different regimes are
presented in Figs. 8 and 9.
With Es = 20 J/cm2, the fine-grained cellular structure as well as
eutectic and partly remelted grain boundary (designated by digits and
arrow in Fig. 8, a) are formed in silumin. The intermetallides in the
structure of the treated layer are ab-
sent. The inclusions of the second phas-
es in eutectic have the average dimen-
sions 1–5 μm. The roughness for the
treated layer Ra equals to 27 nm, while
for the substrate, equals to 57 nm.
The structure of sample cross-sec-
tion treated by the electron beam with
Fig. 7. Atomic-force microscopy of the initial
sample: 1 — intergranular boundary, 2 — den-
dritic grain, 3 — intergranular eutectic
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energy density of electron beam of 25 J/cm2 presented in Fig. 8, b shows
that the treated layer contains the fine-grained structure and the grains
with grain boundary (designated by the digits). The roughness of the
treated layer Ra is 27 nm, and the roughness of substrate is 45 nm. In
the structure of the treated layer, the partially transformed boundaries
Fig. 9. Atomic-force microscopy of silumin after EBT with Es =
= J/cm2 (a) and 35 J/cm2 (b), where arrows show the direction of
electron beam effect. (a) 1 — directionally recrystallized grains
situated in the treated layer, 2 — incompletely melted grain bound-
ary, 3 — grain body. (b) 1 directionally recrystallized grains situ-
ated in the treated layer, 2 — intergranular eutectics, 3 and 4 —
dendritic grains
Fig. 8. Atomic-force microscopy of silumin treated with electron
beam possessing energy density of 20 J/cm2 (a) and 25 J/cm2 (b).
Arrows designate the direction of electron beam effect
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
of grains that were not completely recrystallized (designated by white
arrows in Fig. 8, b) are observed as well.
In the layer after EBT with Es = 30 J/cm2, the directionally recrys-
tallized grains (Fig. 9, a) are revealed. The incompletely melted grain
boundary is designated by 2. The roughness of the treated layer Ra
equals to 33 nm, and the roughness of substrate equals to 51 nm. The
layer structure after EBT with Es = 35 J/cm2 involves the treated layer
1, the grain boundary 2 and grain solids 3 and 4 (Fig. 9, b). The rough-
ness of the treated layer Ra = 17 nm, while the roughness of substrate
equals to 45 nm.
Depending on the energy density of electron beam, the average
roughness of the treated layer Ra varies from 17 to 99 nm, and that of
the substrate varies within the range from 30 to 77 nm. The largest
average value of the layer roughness Ra being equal to 99 nm was ob-
tained in the sample treated by the electron beam with energy density
of electron beam of 10 J/cm2, the least one — 17 nm with energy den-
sity of 35 J/cm2.
The results obtained by means of atomic-force microscope make it
possible to consider that the effective regimes are the regimes of Es
from 25 to 35 J/cm2. In comparison with the other regimes, they are
characterized by the formation of fine-grained cellular structure and
they have the least roughness of the treated layer (of 17–33 nm) and
substrate (of 45–57 nm) as well. The selection of the optimal regime of
treatment according to atomic-force microscopy correlates to the se-
lected regimes according to the results of microhardness measurement.
3.3. Fine Structure and Phase Composition
of the Surface Layers of Silumin after EBT
It was shown by the methods of scanning electron microscopy that silu-
min was a multiphase aggregate, whose structure was presented by the
solid solution grains on aluminium base, the grains of eutectic Al–Si,
the inclusions of the initial silicon, and intermetallides, whose dimen-
sions and shape varied in the rather wide ranges (Fig. 10). The presence
of intermetallides results in the decrease in crack resistance of silumin
[49–52]. Another unfavourable factor of cast alloy structure is the pres-
ence of micropores (Fig. 10, c).
The results of the quantitative x-ray structural analysis are shown
in Table 2. It is seen that the base phases of the tested material, as could
be expected, are the solid solutions based on aluminium and silicon in
the alloy being tested are close to those of pure elements and it indicates
to the layering of these elements on crystallization of the alloy.
The results of the studies of the phase composition and the state of
crystal lattice of silumin surface layer after EBT presented in Table 3
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indicate that three phases are present in the surface layer. The crystal
lattice parameters of the revealed phases differ from the tabular values
for pure elements. The fact can be indicative of formation of solid solu-
tion based on aluminium and silicon taking place at high-speed crystal-
lization of the melted layer.
The smaller values (relative to tabular ones) of Al, silicon, and AlSi-
phase crystal-lattice parameters may be indicative of the alloying of the
phases by the elements with atomic dimensions less than those for Al
and Si: RAl = 0.143 nm, RSi = 0.132 nm, RCu = 0.128 nm, RFe = 0.126 nm,
RNi = 0.124 nm [53].
The electron-microscope image of the transverse metallographic sec-
tion structure presented in Fig. 11 enables one to speak about the fact
that the irradiation by the intense pulsed electron beam results in the
cast material in the surface layer whose thickness varies within 40–
60 μm for the indicated parameters of electron beam (25 J/cm2; 150 μs;
3 pulses).
Fig. 10. SEM images of the structure of silumin in the cast state: a, b, c correspond
to different scales; arrows (c) designate micro pores
Table 3. Results of x-ray structural analysis
of silumin surface irradiated with intense pulsed electron beam
Phase composition Relative content, wt.%
Lattice parameter, nm
irradiated tabular [53]
AlSi 53.13 0.40412
Al 38.29 0.40419 0.40494
Si 8.58 0.54191 0.54307
Table 2. Results of x-ray structural analysis of silumin in the cast state
Phase
Relative
content, wt.%
Lattice type
(space group)
Lattice parameter, nm Atomic
radius, nmtabular, a0 in alloy, à
Al 84.2 Fm3m 0.4050 0.40484 0.143
Si 12.3 Fm3ms 0.54307 0.54265 0.132
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
The structure of the surface layer modified by the electron beam
was studied in more detail by transmission electron microscopy (TEM)
methods of thin foils fabricated from the transverse cross-section of
the samples.
In the surface layer, the cells of two types (Fig. 12) are formed.
First, there are the cells whose volume is free from the second phase
Fig. 13. The structure of silumin surface layer obtained in the cha-
racteristic x-ray radiation of Al (a) and Si (b) atoms
Fig. 12. Electron microscope image of cellular crystallization struc-
ture of silumin surface layer after EBT (Es = 25 J/cm2). Arrows (b)
designate the second phase interlayers located at the cell’s inter-
face boundary
Fig. 11. Electron microscope image of trans-
verse metallographic section structure of silu-
min after EBT (Es = 25 J/cm2). The arrows des-
ignate the irradiation surface and thickness of
the surface layer, in which the initial inclu-
sions of the second phase are not revealed via
SEM methods
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precipitates. In some instances, the round shaped particles located cha-
otically are observed in the volume of these cells. Secondly, the cells in
whose volume the structure of lamellar eutectic (Fig. 12, a) is observed.
Note that the cells of first type at the given irradiation regime are the
predominant type of the structure of the surface layer ≈10 μm thick. At
the larger distance from the irradiation surface, the mixed type struc-
Fig. 15. Electron microscope image of silumin struc-
ture formed as a result of the irradiation with the
intense pulsed electron beam (Es = 25 J/cm2): a, b —
bright field images, c — microelectron diffraction
pattern, d — dark field obtained in the first diffrac-
tion ring [111] Si
Fig. 14. Surface layer structure of silumin foil region formed as a result of super-
position of (a) bright field image and the image obtained in the characteristic x-rays
of silicon atoms, (b) bright field image and the images obtained in the characteristic
x-rays of silicon, copper, and nickel atoms
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
ture presented by the cells of first and second type is formed. The cells
are separated by the thin interlayers of the second phase; the interlayer
dimensions are less than 100 nm (Fig. 12, b).
The studies of the elemental composition of first type and second
type cells (Figs. 13, 14) were performed by the methods of x-ray spec-
trum analysis (method of mapping) [54].
It is established that the volume of first type cells is enriched by Al
atoms (Fig. 13a), that is it represents the Al-based solid solution. The
second type cells are formed by the alternating plates parallel to each
other and enriched by atoms of aluminium (Fig. 13, a) and silicon (Fig.
13, b), i.e. they represent the cells of Al–Si alloy eutectic. The transverse
dimensions of the silicon and aluminium interlayers vary within the
range of 40–60 nm. Si, Cu, Ni, and Fe atoms (Fig. 14) enrich the second
phase interlayers located at the cells’ interface.
Figure 15 shows the results of TEM investigation into the lamellar
eutectic structure. The analysis of microelectron diffraction pattern
(Fig. 15, c) gives grounds for concluding that the plates (Fig. 15, d) are
formed by silicon. The silicon plates are polycrystals with crystal di-
mensions of 5–10 nm. The ring structure of microelectron diffraction
pattern (Fig. 15, c) indicates the nanocrystalline structure of silicon
plates.
Figure 16 illustrates the TEM analysis results of cellular crystalli-
zation structure of silumin. The analysis of microelectron diffraction
Fig. 16. Electron microscope image of silumin struc-
ture formed as a result of the irradiation with the
intense pulsed electron beam (Es = 25 J/cm2): a —
bright field image; c — microelectron diffraction pat-
tern; b, d, e — dark fields obtained in the reflections
[111] Al, [321] Cu15Si4, [220] Si, respectively. Dark
fields (c) are obtained in reflections 1 (b), 2 (d), and
3 (e) designated with arrows
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pattern presented in Fig. 16 depicts that the cells of speed crystalliza-
tion are formed by the solid solution based on aluminium (Fig. 16, b).
The interlayers separating the crystallization cells are the multiphase
formations. The analysis of microelectron diffraction patterns obtained
from the bulks of foil containing the interlayers enabled one to identify
the particles of following phases: Cu15Si4 (Fig. 16, d), silicon (Fig. 16, e),
copper, and Al4Cu9 in the interlayers.
The layer-by-layer TEM analysis of the silumin structures revealed
the graded structure of the surface layers (Fig. 17). The layer of the thick
of 8–10 μm adjoining to the irradiation surface has a cellular structure,
the cells’ boundaries are the second phase interlayers whose thickness is
less than 100 nm (Fig. 17, a). The grains of eutectic are absent.
With the larger distance from the irradiation surface, the cells
(grains) with the lamellar substructure (eutectic) (Fig. 17, b–d) are
found in the cellular crystallization structure. The relative content of
such grains increases with the increase in the distance from the irradia-
tion surface. The first grains of eutectic are identified in the layer lo-
cated at the depth of ≈15 μm. As the distance from the irradiation
surface increases, the relative content of eutectic grains increases. Is-
lands and interlayers between the cells of high-speed crystallization of
aluminium locate the grains of eutectic. The presence of eutectic grains
is indicative of the existence of the local regions with relatively high
concentration (≈12 at.%) of silicon atoms in the surface layer of the
Fig. 17. TEM image of silumin structure after EBT (Es = 25 J/cm2): a — structure
of 5 μm thick layer adjoining to the irradiation surface; b–f — structures of layers
located at distances of x = 15, 30, 50, 120, 200 μm from the irradiation surface,
respectively
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
material. The dimensions of eutectic grains are close to those of solid
solution based on aluminium (crystallization cells). The transverse di-
mensions of eutectic plates vary within the range of 25–50 nm.
The inclusions of intermetallides of cast origin located in the cellular
crystallization structure are found at the depth of 50–70 μm. The inclu-
sions of intermetallides occur as the centres of cellular crystallization.
The layer of silumin, in which only Al melts and the initial inclu-
sions of Si and intermetallides are present, is detected at 80–90 μm
distance from the irradiation surface. In this case, the cells of high-
speed crystallization of Al are observed in the structure. The grains of
lamellar eutectic of submicron dimensions are absent. At a distance of
100–200 μm from the irradiation surface, the cellular crystallization
structure is not revealed (Fig. 17, e, f).
The study of silumin surface after EBT with Es = 35 J/cm2 by the
methods of scanning electron microscopy failed to show the essential
differences from the structure being formed on irradiation with
Es = 25 J/cm2. However, there are some features need to be considered.
It is established that the dimensions of the melted layer increase with
the growth of energy density of electron beam.
At the energy of electron beam of 35 J/cm2, the thickness of the
modified surface layer, in which the initial inclusions of silicon and
intermetallides fail to be detected by SEM method, increases from 70 to
100 μm (Fig. 18, a).
By morphology of the defect substructure, three layers can condi-
tionally be distinguished: the surface layer, transition layer, and the
layer of thermal effect (Fig. 18, a). The surface layer has the structure
of cellular crystallization formed at a high-speed cooling of the material
from the molten state (Fig. 18, b, layer 1). In the layer, the initial inclu-
sions of the second phase fail to be detected by SEM methods. The tran-
sition layer is characterized by the presence of the initial inclusions of
Fig. 18. Electron microscope image of transverse metallographic section structure
of silumin sample after EBT (Es = 35 J/cm2), where the irradiated surface (marked
with an arrow), surface layer (1), transition layer (2), and layer of thermal effect (3)
are designated
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the second phase that are the centres of Al crystallization (Fig. 18, b,
layer 2).
Phase composition and crystal lattice state of silumin modified by
the intense pulsed electron beam were studied by the methods of x-ray
structural analysis, the results of which are given in Table 4.
As one can see from the data in Table 4, the irradiation of silumin
by electron beam results in the formation of two solid solutions based
on aluminium designated in Table as AlSi and Al, the precipitation of
copper aluminide AlCu2 and silicon. The crystal lattice parameter of
AlSi solid solution is less than that of pure aluminium being equal to
0.40494 nm [53]. It is caused by the fact that the atomic radius of sili-
con (0.132 nm) is smaller than that of aluminium (0.143 nm) [53] and
consequently, the substitution of aluminium atoms by silicon will result
in the decrease in the crystal lattice parameter of AlSi solid solution.
The crystal lattice parameter of the second phase based on aluminium
solid solution is larger than that of pure aluminium. It is connected
Table 4. Results of x-ray structural analysis
of silumin modified with intense pulsed electron beam
Phase
composition
Relative
content, wt.%
Lattice parameter, nm Coherent scattering
area, nm
Δd/d, 10−3
a c
AlSi 40.8 0.40435
Si 4.1 0.54274 34.48 2.311
Al 40.7 0.40508
AlCu2 14.4 0.40311 0.57492 29.83 0.926
Table 5. Elemental composition of different regions (1–9)
of cellular substructure of silumin surface layer after treatment
by means of the electron beam with energy density of 25, 30 or 35 J/cm2
Element
Concentration, at.%
Number of region analysed via micro-x-ray spectroscopy
25 J/cm2 30 J/cm2 35 J/cm2
1 2 3 4 5 6 7 8 9
Mg 0.32 0.81 0.44 1.28 0.0 0.14 0.0 0.0 0.0
Al 90.14 89.41 86.83 89.82 92.14 90.97 91.77 91.1 92.83
Si 7.15 6.88 10.36 6.13 5.86 6.25 6.17 3.68 4.69
Ti 0.11 0.13 0.11 0.08 0.04 0.05 0.01 0.13 0.25
Mn 0.02 0.01 0.02 0.02 0.0 0.01 0.0 0.04 0.02
Fe 0.11 0.24 0.12 0.14 0.14 0.07 0.12 0.59 0.1
Ni 0.2 0.6 0.28 0.36 0.37 0.61 0.41 2.02 0.45
Cu 1.94 1.9 1.83 2.17 1.45 1.9 1.53 2.44 1.67
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
with the dissolution of intermetallides particles and the enrichment of
solid solution by atoms of metals whose atomic radius is larger than
that of aluminium. The crystal lattice parameter of Si precipitations is
less than that of the tabular value (aSi = 0.54307 nm) [53]. It means
that, in the process of crystallization, the solid solution based on silicon
is formed, and, in it, the atoms of copper, nickel and iron can be present
because the atomic radii of these elements are less than that of silicon.
The relative content of silicon in the modified layer of silumin is com-
paratively small and by magnitude is close to the value obtained by the
methods of x-ray spectroscopic analysis.
Table 5 illustrates the elemental composition of different parts of
silumin surface layer after EBT. It may be noted that silumin irradia-
tion by the intense pulsed electron beam in the regime of surface layer
melting results in: first, homogenization of the elemental composition
of the surface layer; secondly, the decrease in the concentration of sili-
con atoms in the surface layer being intensified with the growth of en-
ergy density of electron beam.
As it has already been noted, the cellular crystallization structure,
as the distance from the surface of treatment increases, transits to the
structure of the mixed type, in which the partially dissolved inclusions
of the cast origin (Fig. 19) are present along with the cells. The analysis
of the transition type showed the absence of the lamellar form inclu-
sions in the structure. In most cases, the inclusions have a quasi-equi-
axed form (Fig. 19, a). The statement is true for both silicon particles
as well and intermetallide particles. It should be noted that the globu-
larization of silicon particles and intermetallides should substantially
increase in the plastic properties not only of the modified layer but also
the material overall.
Fig. 19. Structure of silumin irradiated with an intense pulsed electron beam (Es =
= 35 J/cm2), where layers at the depths of 70 μm (a) and 90 μm (b) are imaged. The
arrows designate inclusions of the cast origin (initial state)
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3.4. Mechanisms of Electron-Beam Effect on Silumin
The reason for the initiation of the columnar crystallization (Figs. 12,
17) may be the thermocapillary instability, which arises from the pres-
ence of temperature gradient in the liquid layer, and it results in the
formation of vortices (Fig. 20) and the displacement of the second phase
particles to the boundary of columns [55].
The mechanism of the instability and formation of vortices can be
under stood from the following arguments. Let us consider the half-
space z < 0 (Fig. 20). The temperature of the material is maximum on
the surface, and it decreases at the depth. Suppose the surface of liquid
is perturbed with analytical form η (x, t) = A0exp (αt) cos (kx), where α —
exponent, η — displacement of liquid particles from the equilibrium posi-
tion, A0 — amplitude of the displacement, k — wave number. Then, for
the vertical component of velocity, from the kinematical boundary con-
dition, it follows the expression Vz (t, x, 0) = α A0exp (αt) cos (kx). The expo-
nent α depends on wave number k: α = α (k). In literature on the analysis
of instabilities, the value α is still called the growth rate, since the time
derivative of exp (αt) at t ≈ 0 is equal to α. When α > 0, the har monic
oscillation amplitude of liquid increases exponentially resul ting in the
instability. The value α is called increment (decrement), if α > 0 (α < 0).
For the horizontal velocity component, using the continuity condition,
we obtain Vz (t, x, 0) = η∙ = α A' (z) exp (αt) sin (kx)/k. For distribution of tem-
perature, suppose that temperature decreases with increasing z. In the
regions where Vz > 0, the temperature increases. When Vz < 0, the tempe-
rature decreases because the cold substance is carried out from the depth.
The temperature perturbation we shall represent in terms of T (t, x, 0) =
= –Θ (t, z) cos (kx), where Θ (t, z) is amplitude of the present perturbation,
and surface tension coefficient σ (t, x, z) = σ0 + σT Θ (t, z) cos (k, x), σ0—
surface tension at room temperature,
σT — temperature coefficient of surface
tension. For shear stress, fx = ∂σ/∂x –
– σT Θ (t, z) sin (kx). Shear stress acts in a
direction parallel to horizontal velocity,
therefore, the velocity increases. The am-
plitude growth effect consists in it, and
it means that instability develops. This
diagram is true on condition that α > 0,
for the opposite case (α < 0), the system
will be stable and vortices twist in the op-
po site direction resulting in the damping.
Fig. 20. Scheme of electron-beam effect on
silumins
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
As in Ref. [56], we shall model the heat effect of electron beam us-
ing the enthalpy approach. The advantage of the approach is that it
enables to take into account the first-order phase transitions without
invoking the additional conditions. Consider the electron beam effect
(with surface energy density Es) on flat-plate-shaped sample with thick-
ness h. Since we are interested in the temperature depth distribution of
the sample, we restrict ourselves to the solution of one-dimensional
problem of heat conduction. We direct the axis Z inside the plate. The
flow of electrons affects the surface z = 0 during time t0 and on the rear
side of the plate z = h the heat blow is absent. Heat condition equation
in this case reads as
H T
t z z
∂ ∂ ∂⎛ ⎞ρ = λ⎜ ⎟∂ ∂ ∂⎝ ⎠
, (1)
where H — enthalpy, ρ — density, λ — heat conduction coefficient,
T — temperature. Phase transitions under the electron-beam effect are
taken into account as follow:
, ;
( ) , ;
( ) , ;
( ) , ;
, ;
S S L
L L L L L L
L L L L V
V V V V V V
V V V V
C T T T
L T T T T T T
H T C T T T T T
L T T T T T T
C T T T T
ρ <⎧
⎪ρ Δ ≤ ≤ + Δ⎪⎪ρ = ρ + Δ ≤ <⎨
⎪ρ Δ ≤ ≤ + Δ⎪
⎪ρ + Δ ≤⎩
(2)
Cp — coefficient of heat capacity; L — specific heat of phase transition;
indices S, L and V correspond to the solid, liquid, and vapour phase. The
heat flow is set on the surface of the sample (z = 0):
0 0
0 0
0
( ) , 0 ;
( ) ( ); ( )
0, ;
S VE t m T L t t
T z q t q t
t t
− ≤ ≤⎧
−λ ∂ ∂ = = ⎨ >⎩
(3)
( ) (1 ) (2 ),cm T p M RT= − β π pc = p0 exp [LV M (T – TV)/(RTTV)], ES is an
electron-beam energy density, M is a molar mass, R is universal gas
constant, p0 is a pressure at TV, and β is a constant.
At the boundary (z = h),
∂T/∂z = 0. (4)
The initial temperature T (0, z) = Tinit along the entire depth of the
plate is 0 < z < h. Numerical solution of Eqs. (1)–(4) was done via the
implicit difference scheme by the ‘marching’ method.
The thermal physical constants of silumin were calculated by the
rule of mixture. Table 6 represents the values of the constants. As the
conditions of high vacuum were in the experiment, the value of vapori-
zation temperature was calculated according to the Clausius–Clapeyron
equation. It amounted to 1270 K.
472 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
The time and distance distributions of temperature from the irra-
diated silumin surface were calculated for electron beams possessing
energy densities 15–35 J/cm2 with pulse duration t0 = 150 μs.
Figure 21 shows the time distribution of temperature at different
distance from the irradiation surface under the electron-beam effect
with energy density of 35 J/cm2. As one can see on the graphs 1–6, af-
ter the finishing of pulse effect to the moment of time 300 μs, the cool-
ing rate of substance is insignificant. This is indicative of the presence
Fig. 22. Temperature vs. distance from the irradiated sur -
face at different temporal values: 50 (1), 100 (2), 150 (3),
300 (4), 400 (5), and 600 μs (6)
Fig. 21. Time (t) evolution of temperature (T) at different
distances (depths) from the irradiated surface (Es = 35 J/cm2):
0 (1), 10 (2), 20 (3), 25 (4), 30 (5), 50 (6), and 80 μm (7)
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
of the vapour interlayer holding the high temperatures on the surface.
At t > 300 μs, the cooling rate increases abruptly, while its values on
the surface and at the depths to 20 μm (curves 1–3) are higher than at
the depths from 20 to 50 μm (curves 4–6). It is indicative of the expan-
sion of the vapour interlayer. Estimation of cooling rate of surface lay-
ers has shown that it reaches the values of ∼106 K/s. At these values of
cooling rate, as it has been mentioned earlier in Ref. [56], the structure
of cellular crystallization is formed. At the depth of 80 μm (curve 7),
the temperature value is less than the temperature of eutectic.
Analysis of temperature dependence on coordinates (Fig. 22) has
shown that silumin is still in the solid state (curve 1) at a time moment
of 50 μs. The electron-beam action, in this case, decreases, in addition,
to the generation of thermoelastic wave [55] besides the heating. At
t = 100 μs (curve 2), the material is in the molten state within the inter-
val 0–10 μm. Here, the convective flow of the melt starts to develop. To
the moment of time of finishing of pulse action (curve 3), in the interval
from 0 to 15 μm, the substance is in the gaseous state, while the thick-
ness of the evaporated interlayer increases to the moment of time of 300
μs (curve 4). Then, the gradual equalizing of temperature to depth
(curves 5 and 6) is observed.
Table 6. Thermal physical characteristics of silumin [55]
Unit symbol,
unit of measurement
Quantity
value
Description
TL, K 850 Eutectic temperature
TV, K 1 270 Temperature of vaporization
ρS, kg/m3 2 656 Density of silumin in solid state
ρL, kg/m3 2 398 Density of silumin in liquid state
CS, J/(kg·K) 880 Specific heat capacity in solid state
CL, J/(kg·K) 1 160 Specific heat capacity in liquid state
λS, W/(m·K) 200 Heat conduction in solid state
λL, W/(m·K) 86 Heat conduction in liquid state
LL, kJ/kg 385 Specific heat of melting
LV, kJ/kg 10 444 Specific heat of vaporization
Table 7. Calculated and experimental melted layer thicknesses of silicon (dSi),
aluminium (dAl), and silumin specimen (d) irradiated with high-intensity
electron beams (of different densities, Es) for pulse duration of 150 μs
Es, J/cm2 dSi, μm dAl, μm d, μm [57]
15 23 18 23
20 39 39 30
25 54 57 55
35 80 80
474 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
The calculations of melting depth (Table 7) showed that the thick-
ness of the melted layer increases with the growth of energy density
of electron beam. Its values coincide practically with the experimental
ones [57].
We shall use the obtained data on the depth of melting and surface
temperature for the estimation of temperature gradient in development
of the thermocapillary model of surface cellular structure formation.
For the solution of formulated problem, let us take the rectangular
coordinate system (x, y, z) and consider the viscous incompressible heat-
conducting liquid that occupies the layer of thickness h on the free
surface z = η (x, y, t) and absorbs heat. At the values of heat flow of
∼105 W/cm2 used in the experiment, the approximation of the incompres-
sible liquid should be considered as justified in Ref. [58]. After the
electron-beam effect, the temperature in the liquid layer profile is T0 =
= T (z). Let the wave vector of perturbations be directed in XOY plane.
Then, they exponentially depend on the coordinates X, Y, and time:
∝ exp (ωt – i (mx + ly)).
For the study of instability of stationary state, let us linearize Na-
vier–Stokes equation and the equation of heat conduction for tempera-
ture T0 (z) = T (x, y, z, t). They will take the forms as follow:
2 2 2
2 2 2
2 2 2
2 2 2
2 2 2
2 2 2
2 2 2
0
2 2 2
,
,
,
,
0,
u p u u u
t x x y z
v p v v v
t y x y z
w p w w w
t z x y z
u v w
x y x
dTT T T T
w
t dz x y z
⎛ ⎞
⎜ ⎟
⎝ ⎠
⎛ ⎞
⎜ ⎟
⎝ ⎠
⎛ ⎞
⎜ ⎟
⎝ ⎠
⎛ ⎞
⎜ ⎟
⎝ ⎠
∂ ∂ ∂ ∂ ∂= − + ν + +
∂ ρ∂ ∂ ∂ ∂
∂ ∂ ∂ ∂ ∂= − + ν + +
∂ ρ∂ ∂ ∂ ∂
∂ ∂ ∂ ∂ ∂= − + ν + +
∂ ρ∂ ∂ ∂ ∂
∂ ∂ ∂+ + =
∂ ∂ ∂
∂ ∂ ∂ ∂+ = χ + +
∂ ∂ ∂ ∂
(5)
where u, v, w — components of the perturbed-velocity vector; c — en-
sity of the melt; p, T — perturbations of pressure and temperature; ν,
χ, σ (T) — kinematic viscosity, coefficient of heat conduction, and sur-
face tension, respectively. We consider that surface tension depends on
temperature by linear law:
σ = σ0 + σT (T – Tinit), (6)
where σT — temperature coefficient of surface tension, σ0 — surface
tension at room temperature Tinit.
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Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
The boundary conditions on the surface of the melt, z = 0, take the
form:
2 2
2 2
2 ,
, ,
0, .
w
p
z x y
u w v w
z x x z y y
T
w
z t
⎛ ⎞∂ ∂ η ∂ η
− + νρ = σ +⎜ ⎟∂ ∂ ∂⎝ ⎠
⎛ ⎞∂ ∂ ∂σ ∂ ∂ ∂σ⎛ ⎞ρν + = ρν + =⎜ ⎟⎜ ⎟∂ ∂ ∂ ∂ ∂ ∂⎝ ⎠ ⎝ ⎠
∂ ∂η
= =
∂ ∂
(7)
At a melt–solid interface (z = −h), the conditions of adhesion and
impermeability take place [9]:
u = v = w = 0, T = 0. (8)
The gradient of surface tension along the X and Y axes is given by
0 0, .x y
T TT T
a a
x T x z y T y z
∂ ∂⎛ ⎞∂σ ∂σ ∂ ∂σ ∂σ ∂⎛ ⎞= + η = + η⎜ ⎟⎜ ⎟∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂⎝ ⎠ ⎝ ⎠
(9)
Here, the parameter is an introduced for comparing the dispersion equa-
tions obtained in [59] at a = 0 and in [24] at a = 1. Suppose σ0 = 0 and
a = 0, σT ≠ 0, then, we obtain the problem of thermocapillary instability
with undeformed flat boundary (Pirson problem). We search the solu-
tion of Eqs. (5) in terms of
0
( , , , ) ( ) exp ( ( )),
( , , , ) ( ) exp ( ( )),
( , , , ) ( ) exp ( ( )),
( , , , ) ( ) exp ( ( )),
( , , , ) ( ) exp ( ( )),
( , , ) exp ( ( )),
u x y z t U z t i mx ly
v x y z t V z t i mx ly
w x y z t W z t i mx ly
P x y z t P z t i mx ly
T x y z t T z t i mx ly
x y t t i mx ly
= ω − +
= ω − +
= ω − +
= ω − +
= ω − +
η = η ω − +
(10)
where U (z), V (z), W (z), P (z), T (z), η0 are the perturbation amplitudes
of velocity, pressure, temperature, and surface, respectively; k = (l, m)
is a wave vector, i is an imaginary unit. Substituting Eq. (10) into Eqs.
(6)–(8), we obtain the following set:
( )2 2
1 12
1
( ) ( ) ( ) , ( ) ( ) ( ) 0,P z i W z k W z W z k W z P z
k
ρν ′′′ ′ ′′ ′ ′= − − − =
ρν
(11)
where k2
1 = ω/ν + k2, k2
2 = ω/χ + k2, G0 = dT0 /dz. After the transforma-
tion, both equations of the system (11) read as
2 2 2 2
1 1
2
2 0
( ) ( ) ( ) ( ) 0,
( ) ( ) ( / ) ( ) 0.
IVW z k k W z k k W z
T z k T z G W z
′′− + + =
′′ − − χ =
(12)
2
2 0( ) ( ) ( )/ 0.T z k T z G W z′′ − − χ =
476 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
The solutions of the set (12) are as follow:
W (z) = A1 exp (kz) + A2 exp (k1z),
T (z) = C exp (k2z) − (G0/ω) [A1 exp (kz) − A2 δ exp (k1z)], δ = ν/(χ − ν),
(13)
where A1, A2, C are integration constants. Obtaining the dependences
(13), we supposed that h → −∞. In this case, they satisfy the boundary
conditions (8). The constant C was found from the conditions of the
absence of pertrurbations at z → −∞ and was expressed through A1 and A2.
The boundary conditions (7), (8) with an account of the set (10) and
(11) read as
2 2 3 2
1
2 2
1
(0) ( 2 ) (0) (0)/( ) 0,
(0) (0) (0)/ 0,
(0) 0, ( ) ( ) ( ) 0;
c
T
W k k W k W
W k W k
T W W T
ν′′′ ′− + − ω ωω =
′′ + + ω Σ ω =
′ ′= −∞ = −∞ = −∞ =
(14)
ω2
c = (σ0/ρ) k3, ωT = (σTG0)/(νρ), ων = νk2, Σ1(0) = aW(0) + (ω/G0) T (0).
After the substitution (13) into (14) and the subsequent mathemati-
cal transformations, we obtain the set of equations as for A1, A2. The
determinant of the set will be the dispersion equation. Represent this in
terms of Rσ − RT = 0, where
RT = ων ωT
{(1 − z1 /z2) δ (ω2 + 2 ω ων + ω2
c ) +
+ (1 − z1 /z2) (2 ω ων z1 + ω2
c ) + aω [ω + 2 ων(1 − z1)]}, (15)
Rσ = ω2 [(ω + 2 ων)
2 + ω2
c − 4 z1ω2
ν].
At a = 0, the dispersion equation (Rσ − RT = 0) is [58]
ω2 [(ω + 2 ων)
2 + ω2
c − 4 z1ω2
ν] −
− ων ωT
[(1 − z1 /z2) δ (ω2 + 2 ω ων + ω2
c ) + (1 − 1 /z2) (2 ω ων z1 + ω2
c )] = 0 (16)
If a = 1, Rσ − RT = 0 results to (see [24]):
ω2 [(ω + 2 ων)
2 + ω2
c − 4 z1ω2
ν] −
− ων ωT
[(1 − z1 /z2) δ (ω2 + 2 ω ων + ω2
c ) + (1 − 1 /z2) (2 ω ων z1 + ω2
c )] =
= ω [ω + 2 ων(1 − z1)]. (17)
Using substitution ω = ων(z
2
1 − 1) and the subsequent transforma-
tions, Eq. (17) can be reduced to the algebraic equation of the 16th
power. In this case, the solutions satisfying the condition Reω > 0,
Rez1 > 0, and Rez2 > 0 will be unstable ones. The results of the numeri-
cal solution at the temperature gradient G0 = 2.9 ⋅ 1010 K/m are depicted
in Fig. 23. As follows from Fig. 23, the first two solutions of Eq. (17)
are unstable ones.
There is an existence of two dependences of decrement on the wave-
length. In the first case, the decrement maximum occurs at the wave-
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 477
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
length λ = 140 nm, where αmax ≈ 109 s−1 (Fig. 23, a). The comparison with
the experimental data of SEM showed that its values were 3–4 times
less than the cells’ dimensions. This disagreement can be attributed to
the fact that the silicon effect on the value of surface tension, and its
temperature dependence were not taken into account in the present re-
search. The consideration of this effect will be in the scope of another
paper. On the other hand, dependence α on λ (depicted in Fig. 23, a) is
one-model one. Size distribution of high-speed crystallization cells has
the same character. It permits to make a conclusion that thermocapil-
lary instability explains adequately the one-modal character of the dis-
tribution. In the second case, two maximums occur at the wavelengths
λ = 2.6 μm and λ = 9.5 μm (Fig. 23, b), where αmax ≈ 106 s−1. When the
temperature gradient value decreases, as in the first and second cases,
the wavelengths, to which maximum of growth rate falls, increase. The
presence of two decrement dependences on wavelength permits to sug-
gest that the first dependence describes the initiation of crystallization
cells on the surface, while the second one describes the formation of
ordered (periodic) structures of its relief.
4. Summary and Conclusions
The modification of surface layer of hypoeutectic silumin ÀÊ10Ì2Í
(87.88 wt.% of Al and 11.1 wt.% of Si as the base components diluted
with minor impurities of Cu, Ni, Mg, Cr) by means of electron beam of
various energy density (from 10 to 35 J/cm2) was carried out. The com-
plex of investigations of the physical and mechanical properties
(microhardness, friction coefficient, wear resistance, etc.) of silumin
after energy effect in various regimes for determination of their effec-
tive parameters was performed. As found, the microhardness value af-
Fig. 23. Numerically calculated dependences of decrement on the
wavelength (at G0 = 2.9 ∙ 1010 K/m) obtained solving Eq. (17), where
both the first (a) and the second (b) roots of the equation are plotted
478 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
ter EBT depends on the beam energy density and reaches the maximum
values at the following treatment parameters: 25, 30, and 35 J/cm2
(0.93 ± 0.052 GPa for 25 J/cm2, 0.97 ± 0.71 GPa for 30 J/cm2,
0.96 ± 0.103 GPa for 35 J/cm2). Simultaneously, with an increase
of microhardness in the irradiated samples, the decrease of friction
coefficient and wear intensity was observed. In comparison with the
material in as-received state, the friction coefficient decreased by
≈1.3 times, and the wear intensity decreased by ≈6.6 times. By the
methods of atomic-force microscopy, we determined that the fine-
gradient structure was formed in the treated layer, and the defects in
the form of micropores were absent. The roughness of the treated
layer of silumin samples ranges from 17 to 90 nm, while the rough -
ness of the substrate near the treated layer varies in the range from 30
to 77 nm.
In the initial state, silumin is the multiphase aggregate, whose
structure is presented by the grains of solid solution based on alumini-
um, the grains of eutectic Al–Si, the inclusions of the initial silicon,
and intermetallides, whose dimensions and shape vary in wide limits.
EBT results in the homogenization of silicon surface layers and the for-
mation of multilayer gradient structure. The thickness of the homoge-
nized layer varies depending on the parameters of electron-beam treatment
and reaches the maximum values of 100 μm at energy density of 35 J/cm2.
At the density of electron-beam energy of 20 J/cm2 along with more ac-
tive dissolution of intermetallic phase, inclusions located in the surface
layer of the material are observed. Due to the high surface-layer cooling
rate, the elements forming the intermetallides make up the solid solu-
tion in the bulk of aluminium adjoining to the dissolving inclusion. The
melting and high velocity cooling of silumin surface layer results in the
formation of nanocrystalline structure of cellular crystallization, and
the cells’ dimensions vary within the range of 200–500 nm. The thick-
ness of surface layer without the intermetallide particles varies within
the range of 35–100 μm depending on the electron-beam energy density.
The analysis of microelectron diffraction patterns shows that the cells
of speed crystallization are formed by Al-based solid solutions. The in-
terlayers’ separation of the crystallization cells are the multiphase for-
mations containing the particles of Cu15Si4, silicon as well as copper, and
Al4Cu9. The intermetallide inclusions of cast origin located in the struc-
ture of cellular crystallization are revealed at the depth of 50–70 μm.
They play the role of centres of cellular crystallization.
The elemental composition of silumin irradiated by electron beam
varies in a regular way depending on the distance from the irradiation
surface. The melting of silumin by intense pulsed electron beam is ac-
companied with the silicon concentration change in the surface layer up
to 30 μm thick.
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 479
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
The EBT is accompanied with the graded structure formation: when
moving away from the surface of treatment, the cellular crystalliza -
tion structure transforms into the structure of mixed type, where
the partially dissolved inclusions of cast origin are present along with
the cells.
The formation mechanism of cellular and columnar crystallization
structure consisting in the initiation of thermocapillary instability at
vacuum molten metal interface is offered. Analysis of initial stage of
thermocapillary instability development via the solving the dispersion
equation for thermocapillary waves showed that the initiation of nan-
odimensional columnar structure according to this mechanism is ade-
quately explained at the values of temperature gradient of G0 ∼ 1010–1012
K/m. The solution of the complete dispersion equation shows that there
exist two dependences of decrement on the wavelength. The first de-
pendence has one maximum in nanodimensional range; it permits to
conclude that it is responsible for the formation of cellular structure on
the surface. The second dependence has two maximums in microdimen-
sional range, which can be responsible for the formation of periodic
structures on the material surface.
Acknowledgements. The authors express gratitude to K.A. Osintsev,
V.V. Shlyarov, and K.A. Butakova for help in performing the experi-
ments. The study was financially supported by state assignment of
Ministry of Education and Science, RF (project No. 3.1283.2017/4.6).
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[Modification of the Structure and Properties of Eutectic Silumin by Electron–
Ion–Plasma Treatment] (Minsk: Navuka: 2013) (in Russian).
S.V. Panin, A.E. Kolgachev, Yu.I. Pochivalov, V.E. Panin, and I.G. Goriacheva, 44.
Fizicheskaya Mezomekhanika, 8: 101 (2005) (in Russian).
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p. 345 (in Russian).
V. Rotshtein, Yu. Ivanov, and A. Markov, 46. Materials Surface Processing by
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verkhnostnogo Sloya Stali, Podvergnutoy Ehlektronno-Ionno-Plazmennym Meto-
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Received March 26, 2019;
in final version, August 17, 2019
Þ.Ô. ²âàíîâ 1, 2, Ä.Â. Çàãóëÿºâ 3, Ñ. À. Íåâñüêèé 3,
Â.ª. Ãðîìîâ 3, Â.Ä. Ñàðè÷åâ 3, À.Ï. Ñåì³í 3
1 ²íñòèòóò ñèëüíîñòðóìîâî¿ åëåêòðîí³êè Ñ ÐÀÍ,
ïðîñï. Àêàäåì³÷íèé, 2/3, 634055 Òîìñüê, Ðîñ³ÿ
2 Íàö³îíàëüíèé äîñë³äíèöüêèé Òîìñüêèé ïîë³òåõí³÷íèé óí³âåðñèòåò,
ïðîñï. Àêàäåì³÷íèé, 2/3, 634055 Òîìñüê, Ðîñ³ÿ
3 Ñèá³ðñüêèé äåðæàâíèé ³íäóñòð³àëüíèé óí³âåðñèòåò,
âóë. ʳðîâà, 42, 654007 Íîâîêóçíåöüê, Ðîñ³ÿ
̲ÊÐÎÑÒÐÓÊÒÓÐÀ ÒÀ ÂËÀÑÒÈÂÎÑÒ² ÄÎÅÂÒÅÊÒÈ×ÍÎÃÎ
ÑÈËÓ̲ÍÓ, ÎÁÐÎÁËÅÍÎÃÎ ÏÎÒÓÆÍÜÎÑÒÐÓÌÎÂÈÌÈ
²ÌÏÓËÜÑÍÈÌÈ ÅËÅÊÒÐÎÍÍÈÌÈ ÏÓ×ÊÀÌÈ
Ìåòîäàìè ñó÷àñíîãî ô³çè÷íîãî ìàòåð³àëîçíàâñòâà äîñë³äæåíî ñòðóêòóðíî-ôàçîâ³
ñòàíè, ì³êðîòâåðä³ñòü ³ òðèáîëîã³÷í³ âëàñòèâîñò³ äîåâòåêòè÷íîãî ñèëóì³íó ï³ñëÿ
åëåêòðîííî-ïó÷êîâîãî îáðîáëåííÿ. Îá’ºêòîì äîñë³äæåííÿ áóâ äîåâòåêòè÷íèé
ñèëóì³í ìàðêè ÀÊ10Ì2Í ³ç âì³ñòîì 87,88 âàã.% Al é 11,1 âàã.% Si ÿê ãîëîâíèõ
êîìïîíåíò³â. Ïîâåðõíþ ñèëóì³íó ï³ääàâàëè åëåêòðîííî-ïó÷êîâîìó îáðîáëåííþ
â ø³ñòüîõ ð³çíèõ ðåæèìàõ, ùî ð³çíÿòüñÿ ãóñòèíîþ åíåð㳿 ïó÷êà åëåêòðîí³â. ̳-
ðÿííÿ ì³êðîòâåðäîñòè ìîäèô³êîâàíèõ ïîâåðõíåâèõ øàð³â ñèëóì³íó óìîæëèâèëè
ISSN 1608-1021. Usp. Fiz. Met., 2019, Vol. 20, No. 3 483
Microstructure and Properties of Hypoeutectic Silumin Treated by Electron Beams
âèçíà÷åííÿ òðüîõ îïòèìàëüíèõ ðåæèì³â âïëèâó (ç ãóñòèíàìè åíåð㳿 ïó÷êà
åëåêòðîí³â ó 25, 30 ³ 35 Äæ/ñì2), çà ÿêèõ ì³êðîòâåðä³ñòü ï³ääàíèõ ìîäèô³êàö³¿
øàð³â ïåðåâèùóº ì³êðîòâåðä³ñòü ëèòîãî ñèëóì³íó: 0,86 ± 0,041 ÃÏà — ëèòèé
ñòàí; 0,93 ± 0,052 ÃÏà — äëÿ 25 Äæ/ñì2; 0,97 ± 0,071 ÃÏà — äëÿ 30 Äæ/ñì2;
0,96 ± 0,103 ÃÏà — äëÿ 35 Äæ/ñì2. Âèÿâëåíî, ùî åëåêòðîííî-ïó÷êîâå îáðîáëåííÿ
ç îïòèìàëüíèìè ïàðàìåòðàìè ïðèçâîäèòü äî ôîðìóâàííÿ ïîâåðõí³, ìåõàí³÷í³ òà
òðèáîëîã³÷í³ õàðàêòåðèñòèêè ÿêî¿ çíà÷íî ïåðåâèùóþòü â³äïîâ³äí³ çíà÷åííÿ äëÿ
ñèëóì³íó ëèòîãî ñòàíó. Äàí³ àòîìíî-ñèëîâî¿ ì³êðîñêîﳿ êîðåëþþòü ç ðåçóëüòàòàìè
ñòîñîâíî ì³êðîòâåðäîñòè. Îáðîáëåí³ çà ïðåäñòàâëåíèìè ðåæèìàì çðàçêè õàðàê-
òåðèçóþòüñÿ äð³áíîçåðíèñòîþ êîì³ð÷àñòîþ ñòðóêòóðîþ, à òàêîæ ìàþòü íàéìåíøó
øåðñòê³ñòü îáðîáëåíîãî øàðó (17–33 íì) ³ ï³äêëàäèíêè (45–57 íì) ïîð³âíÿíî ç
³íøèìè ðåæèìàìè. Âñòàíîâëåíî, ùî â îáðîáëåíîìó øàð³ ôîðìóºòüñÿ äð³áíî çåð-
íèñòà, ´ðà䳺íòíà, êîì³ð÷àñòà ñòðóêòóðà, ÿêà â ì³ðó â³ääàëåííÿ â³ä ïîâåðõí³
îáðîáëåííÿ ïåðåòâîðþºòüñÿ ó ñòðóêòóðó çì³øàíîãî òèïó. Òîâùèíà ãîìîãåí³çîâàíîãî
øàðó âàð³þ çàëåæíî â³ä ïàðàìåòð³â åëåêòðîííî-ïó÷êîâîãî îáðîáëåííÿ ³ ñÿãàº
ìàêñèìàëüíèõ çíà÷åíü ó 100 ìêì ïðè ãóñòèí³ åíåð㳿 ó 35 Äæ/ñì2. Âèÿâëåíî, ùî
ìîäèô³êîâàíèé øàð â³ëüíèé â³ä ³íòåðìåòàë³ä³â ³ ñêëàäàºòüñÿ ³ç íàíîêðèñòàë³÷íî¿
ñòðóêòóðè êîì³ð÷àñòî¿ êðèñòàë³çàö³¿. Âèñëîâëåíî ïðèïóùåííÿ, ùî ö³ äâà ÷èí íè-
êè ñïðè÷èíþþòü ï³äâèùåííÿ ìåõàí³÷íèõ ³ òðèáîëîã³÷íèõ õàðàêòåðèñòèê ìîäè-
ô³êîâàíîãî øàðó. Çàïðîïîíîâàíî ìåõàí³çì óòâîðåííÿ ñòðóêòóðè êîì³ð÷àñòî¿ òà
ñòîâï÷àñòî¿ êðèñòàë³çàö³¿, ÿêèé ïîëÿãຠó âèíèêíåíí³ òåðìîêàï³ëÿðíî¿ íå ñò³é-
êîñòè íà ìåæ³ ïîä³ëó «âèïàðóâàíà ðå÷îâèíà/ð³äêà ôàçà». Ðîçðîáëåíî ìàòå ìàòè÷-
íèé ìîäåëü òåïëîâîãî âïëèâó åëåêòðîííîãî ïó÷êà íà ïîâåðõíåâ³ øàðè ñèëóì³íó.
Êëþ÷îâ³ ñëîâà: ô³çè÷íà ïðèðîäà, ìàòåìàòè÷í³ ìîäåë³, ñòðóêòóðà, âëàñòèâîñò³,
äîåâòåêòè÷íèé ñèëóì³í, åëåêòðîííî-ïðîìåíåâå îáðîáëåííÿ, ôàçîâèé ñêëàä.
Þ.Ô. Èâàíîâ 1, 2, Ä.Â. Çàãóëÿåâ 3, Ñ.À. Íåâñêèé 3,
Â.Å. Ãðîìîâ 3, Â.Ä. Ñàðû÷åâ 3, À.Ï. Ñåìèí 3
1 Èíñòèòóò ñèëüíîòî÷íîé ýëåêòðîíèêè ÑÎ ÐÀÍ,
ïðîñï. Àêàäåìè÷åñêèé, 2/3, 634055 Òîìñê, Ðîññèÿ
2 Íàöèîíàëüíûé èññëåäîâàòåëüñêèé Òîìñêèé ïîëèòåõíè÷åñêèé óíèâåðñèòåò,
ïðîñï. Àêàäåìè÷åñêèé, 2/3, 634055 Òîìñê, Ðîññèÿ
2 Ñèáèðñêèé ãîñóäàðñòâåííûé èíäóñòðèàëüíûé óíèâåðñèòåò,
óë. Êèðîâà, 42, 654007 Íîâîêóçíåöê, Ðîññèÿ
ÌÈÊÐÎÑÒÐÓÊÒÓÐÀ È ÑÂÎÉÑÒÂÀ ÄÎÝÂÒÅÊÒÈ×ÅÑÊÎÃÎ
ÑÈËÓÌÈÍÀ, ÎÁÐÀÁÎÒÀÍÍÎÃÎ ÑÈËÜÍÎÒÎ×ÍÛÌÈ
ÈÌÏÓËÜÑÍÛÌÈ ÝËÅÊÒÐÎÍÍÛÌÈ ÏÓ×ÊÀÌÈ
Ìåòîäàìè ñîâðåìåííîãî ôèçè÷åñêîãî ìàòåðèàëîâåäåíèÿ èññëåäîâàíû ñòðóêòóðíî-
ôàçîâûå ñîñòîÿíèÿ, ìèêðîòâ¸ðäîñòü è òðèáîëîãè÷åñêèå ñâîéñòâà äîýâòåêòè÷åñêî-
ãî ñèëóìèíà ïîñëå ýëåêòðîííî-ïó÷êîâîé îáðàáîòêè. Îáúåêòîì èññëåäîâàíèÿ ÿâ-
ëÿëñÿ äîýâòåêòè÷åñêèé ñèëóìèí ìàðêè ÀÊ10Ì2Í ñ ñîäåðæàíèåì 87,88 âåñ.% Al
è 11,1 âåñ.% Si êàê ãëàâíûõ êîìïîíåíòîâ. Ïîâåðõíîñòü ñèëóìèíà ïîäâåðãàëàñü
ýëåêòðîííî-ïó÷êîâîé îáðàáîòêå â øåñòè ðàçëè÷íûõ ðåæèìàõ, îòëè÷àþùèõñÿ ïëîò-
íîñòüþ ýíåðãèè ïó÷êà ýëåêòðîíîâ. Èçìåðåíèÿ ìèêðîòâ¸ðäîñòè ìîäè ôèöè ðî âàí-
íûõ ïîâåðõíîñòíûõ ñëî¸â ñèëóìèíà ïîçâîëèëè îïðåäåëèòü òðè îïòèìàëüíûõ ðå-
æèìà âîçäåéñòâèÿ (ñ ïëîòíîñòÿìè ýíåðãèè ïó÷êà ýëåêòðîíîâ 25, 30 è 35 Äæ/ñì2),
ïðè êîòîðûõ ìèêðîòâ¸ðäîñòü ïîâåðãíóòûõ ìîäèôèêàöèè ñëî¸â ïðåâûøàåò
ìèê ðî òâ¸ðäîñòü ëèòîãî ñèëóìèíà: 0,86 ± 0,041 ÃÏà — ëèòîå ñîñòîÿíèå; 0,93 ±
± 0,052 ÃÏà — äëÿ 25 Äæ/ñì2; 0,97 ± 0,071 ÃÏà — äëÿ 30 Äæ/ñì2; 0,96 ±
484 ISSN 1608-1021. Prog. Phys. Met., 2019, Vol. 20, No. 3
Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Å. Gromov et al.
± 0,103 ÃÏà — äëÿ 35 Äæ/ñì2. Îáíàðóæåíî, ÷òî ýëåêòðîííî-ïó÷êîâàÿ îáðàáîòêà
ñ îïòèìàëüíûìè ïàðàìåòðàìè ïðèâîäèò ê ôîðìèðîâàíèþ ïîâåðõíîñòè, ìåõà íè-
÷åñêèå è òðèáîëîãè÷åñêèå õàðàêòåðèñòèêè êîòîðîé çíà÷èòåëüíî ïðåâûøàþò ñî-
îò âåòñòâóþùèå çíà÷åíèÿ äëÿ ñèëóìèíà ëèòîãî ñîñòîÿíèÿ. Äàííûå àòîìíî-ñè ëî-
âîé ìèêðîñêîïèè êîððåëèðóþò ñ ðåçóëüòàòàìè ïî ìèê-ðîòâ¸ðäîñòè. Îáðàáî òàí-
íûå ïî ïðåäñòàâëåííûì ðåæèìàì îáðàçöû õà-ðàêòåðèçóþòñÿ ìåëêîçåðíèñòîé
ÿ÷åèñòîé ñòðóêòóðîé, à òàêæå èìåþò íàèìåíüøóþ øåðîõîâàòîñòü îáðàáîòàííîãî
ñëîÿ (17–33 íì) è ïîäëîæêè (45–57 íì) ïî ñðàâíåíèþ ñ äðóãèìè ðåæèìàìè.
Óñòàíîâëåíî, ÷òî â îáðàáîòàííîì ñëîå ôîðìèðóåòñÿ ìåëêîçåðíèñòàÿ, ãðàäèåíòíàÿ,
ÿ÷åèñòàÿ ñòðóêòóðà, êîòîðàÿ ïî ìåðå óäàëåíèÿ îò ïîâåðõíîñòè îáðàáîòêè ïðåâ-
ðàùàåòñÿ â ñòðóêòóðó ñìåøàííîãî òèïà. Òîëùèíà ãîìîãåíèçèðîâàííîãî ñëîÿ
âàðüèðóåòñÿ â çàâèñèìîñòè îò ïàðàìåòðîâ ýëåêòðîííî-ïó÷êîâîé îáðàáîòêè è äîñ-
òèãàåò ìàêñèìàëüíûõ çíà÷åíèé 100 ìêì ïðè ïëîòíîñòè ýíåðãèè 35 Äæ/ñì2.
Îáíàðóæåíî, ÷òî ìîäèôèöèðîâàííûé ñëîé ñâîáîäåí îò èíòåðìåòàëëèäîâ è ñîñ-
òîèò èç íàíîêðèñòàëëè÷åñêîé ñòðóêòóðû ÿ÷åèñòîé êðèñòàëëèçàöèè. Âûñêàçàíî
ïðåäïîëîæåíèå, ÷òî ýòè äâà ôàêòîðà ÿâëÿþòñÿ ïðè÷èíîé ïîâûøåííûõ ìåõàíè-
÷åñêèõ è òðèáîëîãè÷åñêèõ õàðàêòåðèñòèê ìîäèôèöèðîâàííîãî ñëîÿ. Ïðåäëîæåí
ìåõàíèçì îáðàçîâàíèÿ ñòðóêòóðû ÿ÷åèñòîé è ñòîëá÷àòîé êðèñòàëëèçàöèè, êîòî-
ðûé çàêëþ÷àåòñÿ â âîçíèêíîâåíèè òåðìîêàïèëëÿðíîé íåóñòîé÷èâîñòè íà ãðàíè-
öå ðàçäåëà «èñïàð¸ííîå âåùåñòâî/æèäêàÿ ôàçà». Ðàçðàáîòàíà ìàòåìà òè÷åñêàÿ
ìîäåëü òåïëîâîãî âîçäåéñòâèÿ ýëåêòðîííîãî ïó÷êà íà ïîâåðõíîñòíûå ñëîè
ñèëóìèíà.
Êëþ÷åâûå ñëîâà: ôèçè÷åñêàÿ ïðèðîäà, ìàòåìàòè÷åñêèå ìîäåëè, ñòðóêòóðà, ñâîé-
ñòâà, äîýâòåêòè÷åñêèé ñèëóìèí, ýëåêòðîííî-ïó÷êîâàÿ îáðàáîòêà, ôàçîâûé ñîñòàâ.
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| id | nasplib_isofts_kiev_ua-123456789-167933 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1608-1021 |
| language | English |
| last_indexed | 2025-11-30T09:55:08Z |
| publishDate | 2019 |
| publisher | Інститут металофізики ім. Г.В. Курдюмова НАН України |
| record_format | dspace |
| spelling | Ivanov, Yu.F. Zagulyaev, D.V. Nevskii, S.A. Gromov, V.Е. Sarychev, V.D. Semin, A.P. 2020-04-16T18:50:30Z 2020-04-16T18:50:30Z 2019 Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams / Yu.F. Ivanov, D.V. Zagulyaev, S.A. Nevskii, V.Е. Gromov, V.D. Sarychev, A.P. Semin // Progress in Physics of Metals. — 2019. — Vol. 20, No 3. — P. 447-484. — Bibliog.: 59 titles. — eng. 1608-1021 DOI: https: //doi.org/10.15407/ufm.20.03.447 https://nasplib.isofts.kiev.ua/handle/123456789/167933 The structural-phase states, microhardness, and tribological properties of hypoeutectic silumin after electron-beam treatment are studied by the methods of contemporary physical materials science. The object of the study is hypoeutectic АК10М2Н-type silumin containing 87.88 wt.% of Al and 11.1 wt.% of Si as the base components. Методами сучасного фізичного матеріалознавства досліджено структурно-фазові стани, мікротвердість і трибологічні властивості доевтектичного силуміну після електронно-пучкового оброблення. Об єктом дослідження був доевтектичний силумін марки АК10М2Н із вмістом 87,88 ваг.% Al й 11,1 ваг.% Si як головних компонентів. Методами современного физического материаловедения исследованы структурнофазовые состояния, микротв рдость и трибологические свойства доэвтектического силумина после электронно-пучковой обработки. Объектом исследования являлся доэвтектический силумин марки АК10М2Н с содержанием 87,88 вес.% Al и 11,1 вес.% Si как главных компонентов. The authors express gratitude to K.A. Osintsev, V.V. Shlyarov, and K.A. Butakova for help in performing the experiments. The study was financially supported by state assignment of Ministry of Education and Science, RF (project No. 3.1283.2017/4.6). en Інститут металофізики ім. Г.В. Курдюмова НАН України Успехи физики металлов Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams Мікроструктура та властивості доевтектичного силуміну, обробленого потужньо струмовими імпульсними електронними пучками Микроструктура и свойства доэвтектического силумина, обработанного сильноточными импульсными электронными пучками Article published earlier |
| spellingShingle | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams Ivanov, Yu.F. Zagulyaev, D.V. Nevskii, S.A. Gromov, V.Е. Sarychev, V.D. Semin, A.P. |
| title | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| title_alt | Мікроструктура та властивості доевтектичного силуміну, обробленого потужньо струмовими імпульсними електронними пучками Микроструктура и свойства доэвтектического силумина, обработанного сильноточными импульсными электронными пучками |
| title_full | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| title_fullStr | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| title_full_unstemmed | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| title_short | Microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| title_sort | microstructure and properties of hypoeutectic silumin treated by high-current pulsed electron beams |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/167933 |
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