Microstructure Characterization of Nanocrystalline Ni₅₀Ti₅₀ Alloy Prepared Via Mechanical Alloying Method Using the Rietveld Refinement Method Applied to the X-Ray Diffraction

• Дата: 2017
• Автори: Sakher, E., Loudjani, N., Benchiheub, M., Belkahla, S., Bououdina, M.
• Формат: Стаття
• Мова: English
• Опубліковано: Інститут металофізики ім. Г.В. Курдюмова НАН України 2017
• Назва видання: Наносистеми, наноматеріали, нанотехнології
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/133487
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Microstructure Characterization of Nanocrystalline Ni₅₀Ti₅₀ Alloy Prepared Via Mechanical Alloying Method Using the Rietveld Refinement Method Applied to the X-Ray Diffraction / E. Sakher, N. Loudjani, M. Benchiheub, S. Belkahla, M. Bououdina // Наносистеми, наноматеріали, нанотехнології: Зб. наук. пр. — К.: РВВ ІМФ, 2017. — Т. 15, № 3. — С. 401–416. — Бібліогр.: 27 назв. — англ.

Using the Rietveld refinement, we analysed the structural evolution of Ni₅₀Ti₅₀ alloy prepared by mechanical alloying method. The elemental Ti and Ni powders are milled during different milling times (0, 1, 3, 6, 24, and 72 hours) in a high-energy planetary ball mill (Pulverisette 7 premium line). The milled powder specimens were characterized with x-ray Philips X,Pert diffractometer equipped with CuKα radiation source (λCu = 0.15418 nm). We refined the structure of compounds using the MAUD program, and we found structural parameters such as the atomic positions (x, y, z), symmetry, and a space group. Moreover, microstructural parameters such as the lattice parameters (a, b, c), the average crystallite size <L>, microstrains <σ₂>¹/², the average number of compacted layers, and the phase percentages were also determined. According to the results, at the initial stages of milling (typically of 1–3 h), the structure consists of Ni-based solid solution [f.c.c.-Ni (Ti)], Ti-based solid solution [h.c.p.-Ti (Ni)], and amorphous phase (??40 wt.%). Based on the data evaluated during milling, the nanocrystalline NiTi-martensite (B19') and NiTi-austenite (B2) phases are initially formed from the primary materials and from the amorphous phase.