Ni_(75)Al_(5.5)V_(19.5)合金沉淀行为的微观相场模拟  

Simulation of the Precipitation Process of Ni_(75)Al_(5.5)V_(19.5) Alloy Using Microscopic Phase-Field Method

作　　者：李永胜[1] 陈铮[1,2] 王永欣[1] 张建军[1] 

机构地区：[1]西北工业大学 [2]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《稀有金属材料与工程》2006年第7期1030-1034,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金资助(50071046);国家"863"高新技术研究计划项目(2002AA331051)

摘　　要：利用微观相场方法模拟了Ni75Al5.5V19.5合金两种有序相D022和L12随温度变化时的不同沉淀过程。发现过冷度在相变驱动力中处于主导地位。高温下D022相首先析出,之后L12相在D022相和无序相的界面以及D022相形成的界面处析出,L12相长大时同时向无序基体和D022相推移;低温下L12相先析出,D022相在L12相的界面处形核长大,同时L12相通过失稳分解由非化学计量相向平衡相转变,其尺寸减小。该合金最终两相体积分数同时达到平衡并基本相等。随温度降低,L12相由高温时的非经典形核与失稳分解的混合机制向低温时的失稳分解转变;D022相的沉淀机制由非经典形核与失稳分解的混合机制向低温时的非经典形核转变。The precipitation processes of the ordered phases D022 and L1 2 in Ni75Al5.5V19.5 alloy at different temperatures were studied using the microscopic phase-field method. It is found that the supercooling degree is the main factor for the phase transformation. The D022 phase precipitates at a higher temperature firstly, then the L1 2 phase precipitates at the phase boundaries of D022 and disordered phases and round the interphase of D022 forming. The L1 2 phase grew towards the disordered matrix and the D022 phase nearly at the same time. Then at a lower temperature, the L1 2 phase precipitates firstly, then the D022 phase precipitates at the ordered interphase of L1 2 phase, which transforms from a nonstoichiometric phase to a equilibrium phase through spinodal decomposition and the dimension becomes smaller. The volume fractions of the two phases are almost equal at last. With the temperature decreasing, the precipitation mechanism of L1 2 phase transforms from the mixed pattern of non-classical nucleation and spinodal decomposition of higher temperature to the spinodal decomposition of lower temperature, but the precipitation mechanism of D022 phase transforms from the mixed pattern to the non-classical nucleation.

关 键 词：微观相场 Ni75Al5.5V19.5合金 沉淀 模拟 

分 类 号：TG111[金属学及工艺—物理冶金]