Microscopic phase-field simulation of atomic migration characteristics in Ni₇₅Al_xV_25-x alloys

Atomic migration characteristics of phase transformation in Ni₇₅Al_xV_25-x alloys were investigated with the microscopic phase-field simulation. The results show that the preferential growth direction of D0₂₂ is the [100] direction, L1₂ phase is substituted by D0₂₂ along this direction, the D0₂₂ results in a plates shape and is parallel to L1₂ at the final. The atomic substitution behavior in the [100] direction also exhibits the site preference, which results in the changeless of Ni atom plans of L1₂ and D0₂₂, thus the substitution modes have the least atom jump quantities, the minimizing energy of atomic jump is accordant with the particles alignment along the elastic soft directions. It is also found that the atomic substitution modes of L1₂ → D0₂₂ in the early stage are similar to that of D0₂₂ → L1₂.