Дослідження морфології багатошарових включень в сплавах системи Fe-C-Mn-Si-Ti-Al-N

• Дата: 2023
• Автори: Філоненко, Наталія, Бабаченко, Олександр, Кононенко, Ганна
• Формат: Стаття
• Мова: Українська
• Опубліковано: Physico-technological Institute of Metals and Alloys 2023
• Теми: сплав системи Fe-C-Mn-Si-Ti-Al-N; оксид алюмінію; фаза AlTiO3; енергія Гіббса
• Онлайн доступ: https://www.metalsandcasting.com/index.php/mcu/article/view/31
• Назва журналу: Metal and Casting of Ukraine

In this work, the microstructure of the Fe-C-Mn-Si-Ti-Al-N alloy and the structure of multiphase inclusions were studied. To determine the structural state of the alloys, microstructural, X-ray microspectral, and X-ray phase analyzes were used. It should be noted that the lines of the Al2O3 phase in the diffraction pattern are shifted towards larger angles, which can be explained by doping the phase with titanium. It is shown that after casting, individual multilayer inclusions were found in the alloy structure, which had a size of 1.5–2 μm and were in a solid solution of a-iron. At the center of the multiphase inclusion is aluminum oxide Al2O3 doped with titanium. The inner layer of the inclusion is formed during the crystallization of the alloy – the AlTiO3 phase, around which the phase formed by the peritectic reaction was observed L + (AlTi)2O3 → (Ti0,3 Fe0,2)(N0,3 С0,2). The multilayer inclusion was surrounded by ferrite containing up to 1.0 % (at.) manganese, 1.7 % (at.) silicon, 1.0 % (at.) titanium, and 0.032 % (at.) carbon. It is known that the thermodynamic functions of phases make it possible to predict the physical and chemical properties of alloys under changing external conditions, such as temperature, pressure, etc. So far, methods for calculating the thermodynamic functions of phases are known, which can be used only under equilibrium conditions and do not take into account fluctuation processes. Therefore, in this work, for the first time, taking into account the contribution of the first step of the approximation of the high-temperature development of the thermodynamic potential, the dependences of the Gibbs energy on the temperature of the Al2O3 and AlTiO3 phases were obtained. A comparison of the Gibbs energies of the Al2O3 and AlTiO3 phases showed that the formation of the AlTiO3 phase is more energetically favorable than that of Al2O3. After subsequent processing – heating to (1533 ± 10) K for 1–2 hours and hot deformation with a degree of deformation of 50 %, the AlTiO3 phase was not detected in the microstructure of the alloy under study, since it is metastable and disappears after subsequent processing. The formation of titanium nitrides TiN was observed in the microstructure of the alloy.