Microscopic phase field simulation for the evolution of antisite defect of L12 structure and D022 structure in Ni75Al5.3V19.7 alloy

The antisite defect for L12-structure Ni3Al and D022-structure Ni3V of Ni75Al5.3V19.7 alloy is studied by microscopic phase field method in this paper. The results show that the concentration of antisite defects AlNi，VNi and NiAl for L12 structure，VNi, AlNi,Niv and AlV for D022 structure all decrease with precipitate process and reach to equilibrium values at the early stage of precipitation respectively. With the elapse of time, the two structures grow up while the concentrations of antisite defects always keep unchanged. The concentrations of equilibrium state antisite defects AlNi and VNi for L12 structure α site, VNi and AlNi for D022 structure α site are of the 10-2 order, and antisite defect NiAl for L12 structure β site, NiV for D022 structure β site are of 10-1 order, the two defects being the main antisite defects for the L12 and D022 structures. The addition element has a great site-preference for a certain ordered phase, V atom prefers to occupy L12 structure β site while Al atom prefers to occupy D022 structure α site.