Microscopic phase field simulation on the evolution of ordered domain interface in Ni₇₅Al_7.5V_17.5 alloy

In order to study the effect of atomic structure on the migration characteristic and solute evolution of ordered domain interfaces, the precipitation process of Ni₇₅Al_7.5V1_7.5 alloy was simulated based on microscopic phase field model. Two types of ordered domain interfaces formed between DO₂₂ phases and two types of ordered domain interfaces formed between DO₂₂ and L1₂ phase which are formed in the precipitation process were studied. The results show that the migration ability depends on the atomic structure of interfaces, among the four types of ordered domain interfaces, interface (100)_D//(200) _L and {102}_D·1/2[001]_D can migrate, while (001)_D//(002)_L and (002)_D (100) _D·1/2[100]_D can not migrate. During the migration process of ordered domain interfaces, the jump of atoms show site selectivity, and the jump and substitute mode of atoms is the optimist way in aspect of kinetics and thermodynamics to induce interface migration. The degree and preference of segregation or depletion of alloy elements are different at different interfaces. Ni segregated at the DO₂₂ side and depleted at the L1₂ side of interface (001)_D//(002)_L, while Ni segregated at both DO22 and L12 sides of interface (100)_D//(200) _L. Al segregated at interface {102}_D·1/2[001] _D but depleted at the interface (002)_D// (100) _D·1/2[100]_D. The preferences of segregation or depletion of alloy elements remain unchanged when the position of interface changes during the migration because of the solute trap effect, but the degree of segregation or depletion of alloy elements become lower during the interface migration process, and the interface become sharper.