Microscopic phase field study on the site preference of Al in Ni ₃V: Coordination geometry effect

The site occupation behavior of Al in Ni₃V phase with a DO ₂₂ structure in Ni₇₅Al_xV_25-x alloy was studied using the microscopic phase-field model which is based on the microscopic diffusion equations. Attribute to the coordination geometry effects, the concentration of Al are non-equal on the two non-equivalent Ni sites, and Al prefers to occupy the Ni_Isites. However, the Al does not prefer to occupy both of the two Ni sites, because the Al concentration on V site is intermediately between that on Ni_Iand Ni_IIsite. The calculated ordering energies suggest that the site preference of alloying elements are all energetic favorable.