Ni75Al7.5V17.5相变过程中L12相合金元素占位几率演化的微观相场模拟

摘要

基于微观相场模型,研究Ni75Al7.5V17.5合金在相变过程中L12相内合金元素演化与DO22相生长之间的关系.研究表明,在L12相向DO22相转变的过程中,DO22相的长大可以分为两阶段.在早期,L12相内合金元素的成分基本不变,DO22相的长大主要受L12相间有序畴界的减少所控制.在后期,DO22相长大所需的V一部分来自L12相内部,一部分来自L12相体积的减少,其中,相内部为DO22相长大所提供的V则主要来自Al格点位置,由于L12相体积减少而富余的Al向L12相内部扩散迁移并主要占据Al格点位置,富余的Ni则同时向L12相内部和DO22相内部扩散,主要占据L12相的Ni位置.DO22相长大的后期主要受L12相内反位缺陷和第三组元的演化所控制.%Correlation between site occupation evolution of-alloying elements in L12 'phase and growth of DO22 phase in Ni75Al7.sV1 7.5 was studied using microscopic phase field model.The results demonstrate that the growing process of DO22 phase can be divided into two stages.At the early stage,composition in the centre part of L12 phase almost remains unchanged,and the nucleation and growth of DO22 phase is controlled by the decrease of interface between L12 phases.At the late stage,part of V for growth of DO22 phase is supplied from the centre part of L12 phase and mainly comes from Al sublattice,the excess Ni spared from the decreasing L 12 phase migrates into the centre part of L 12 phase and occupies the Ni sublattices exclusively,while the excess Al mainly occupies the Al sublattice.At the late stage,the growth of DO22 phase is controlled by the evolution of antisite atoms and ternary additions in the centre part of L 12 phase.