Fe-C二元合金包晶相变的相场法模拟

以Fe-0.79 mol%C二元合金为例,采用多相场法,模拟研究了包晶相变过程中不同过冷度下奥氏体的演化过程,讨论了过冷度对奥氏体生长速度与形貌的影响.结果表明:包晶反应过程中,在界面迁移率与溶质富集的影响下,靠近三相节点处的部分δ相重熔,导致γ相向δ相内生长;当液相中的球状δ相表面发生包晶相变时,γ相作为一个外壳包围着δ相生长,最后在δ相周围形成一层γ相的核壳;随着过冷度的增加,包晶相变的驱动力增加,γ相的生长速度加快,γ相包围δ相的量越多。

Phase-field simulation on the peritectic phase transition in Fe-C binary alloy

In this study, taking Fe-0.79 mol%C binary alloy as an example, the evolution of austenite in different supercooling degree during peritectic phase transition is simulated by multiphase field method, and the influences of supercooling degree on austenite growth rate as well as austenite morphology are discussed respectively. The simulation results show that in the process of peritectic reaction and influenced by interfacial mobility and solute enrichment, part of δ phase near the three-phase junction remelted, resulting in the growth of γ phase into δ phase. When the peritectic phase transition occurs on the surface of the spherical δ phase in liquid phase, the γ phase grows around the δ phase as a shell, and finally forms a core shell around the δ phase. With the increase of undercooling, the driving force of peritectic transformation increases, the growth rate of γ phase accelerates, and the amount of δ phase surrounded by γ phase increases.