Site occupation evolution of alloying elements in Ni_3 V phase during phase transformation in Ni_(75)Al_(4.2)V_(20.8)

Ni_(75)Al_(4.2)V_(20.8)相变过程中DO_(22)相合金元素占位几率演化的微观相场模拟（英文）

Based on the microscopic phase-field model, the correlation between site occupation evolution of alloying elements in Ni3V-DO22 phase and growth of Ni3Al-L12 phase was studied during the phase transformation of Ni75Al4.2V20.8. The results demonstrate that the growth of L12 phase can be divided into two stages： at the early stage, the composition of alloying elements in DO22 phase almost remains unchanged; at the late stage, the compositions of Ni and Al decrease while V increases in DO22 phase. Part of alloying elements for L12 phase growth are supplied from the site occupation evolution of alloying elements on three kinds of sublattices in DO22 phase. Ni is mainly supplied from V sublattice, and part of Al is supplied from NiⅠ and V sites at the centre of DO22 phase. The excessive V from the decreasing DO22 phase migrates into the centre of DO22 phase and mainly occupies V and NiII sites. It is the site occupation evolution of antisite atoms and ternary additions in DO22 phase that controls the growth rate of L12 phase at the late stage.

基于微观相场模型,研究Ni75Al4.2V20.8相变过程中Ni3V-DO22相中合金元素占位几率演化规律与Ni3Al-L12相长大之间的内在关联。结果表明L12相长大过程可以分为两个阶段。在前期,DO22相内合金元素的成分基本保持不变;在后期,DO22相中Ni和Al的浓度降低,而V的浓度升高。合金元素在DO22相中各个格点位置上的浓度发生不同变化;为L12相长大后期提供部分合金元素:其中,Ni主要来源于DO22相中的V格点位置;Al主要来源于NiI和V格点位置;由于DO22相体积减少而富余的V向DO22相内部扩散,主要占据V和NiII格点位置。L12相长大的后期主要受DO22相内反位缺陷和第三组元的演化所控制。