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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 transition of L12 phase and DO22 in Ni64Al21V15 alloy at 1150 K was studied by using the microscopic phase field dynamics model. The probability of the alloying and its evolution at different atomic planes and lattice sites of the alloying elements were analyzed in detail. Atomic migration mechanism. It is found that there are two types of crystal orientation relationship between L12 phase and DO22 phase in Ni64Al21V15 alloy precipitation process: (001) L12 → (001) DO22 and (001) L12 → (100) DO22. Al, V and Ni atoms first transition across the atomic planes, and then enrich and atomize each atom plane from uniform and disordered states, and the ordering reactions occur simultaneously. The Al and V atoms preferentially occupy the β and β1 positions (mainly Al atoms), and the Ni atoms preferentially occupy the α1 and β2 positions. The Al, V and Ni atoms then migrate in-plane, with Al atoms occupying β1 and α1 positions, V atoms occupying β and β2 positions, and Ni atoms occupying α1 positions, resulting in the conversion of L12 phase to DO22 phase.