微观相场模拟Ni_(64)Al_(21)V_(15)合金中L1_2、DO_(22)相形成的原子迁移

Microscopic Phase-Field Simulation of the Atomic Migration of L1_2 and DO_(22) Phase Formation in Ni_(64)Al_(21)V_(15) Alloy

利用微观相场动力学模型研究Ni64Al21V15合金1150K下的L12相、DO22相转变的过程,详细分析合金元素在两相中不同原子面和各个格点上的占位几率及其演化过程,探讨原子迁移机制。研究发现Ni64Al21V15合金沉淀过程L12相向DO22相结构转变存在两种晶体学位向关系类型:(001)L12→(001)DO22和(001)L12→(100)DO22。Al、V和Ni原子首先在原子面间跃迁,由均匀、无序的状态分别向各原子面富集,同时发生有序化反应。Al和V原子优先占据β和β1位(以Al原子为主),Ni原子优先占据α1和β2位。随后Al、V和Ni原子在面内迁移,Al原子占据β1和α1位,V原子占据β和β2位,Ni原子主要占据α1位,从而实现L12相转变成DO22相。

The phase transformation process of dynamic model of L12 and DO22 phase in Ni64Al21V15 alloy at 1150 K was studied by micro-phase field model. The migration of Al, V and Ni atoms in the two phases in the different lattice faces and at different sites was analyzed, and its evolution was researched. The results show that there are two types of crystallographic orientation relationship between L12 and DO22 ： （001） L12 →（001） DO22 and （001） L12 →（100） DO22 . In the structure transformation form L12 to DO22 , the atomic ordering is proceeded on each plane as the atoms migrate between different planes, Al and V occupy the β and β1 sites prior to others, Ni occupy the α1 and β2 sites, and the nonordered domain gradually transforms to the L12 structure. Then, the atomic ordering is proceeded on each plane as the atoms migrate on planes only, Al occupy the β1 and α1 sites, V occupy the β and β2 sites, Ni mainly occupy the α1 site, and L12 structure transforms into DO22 structure.