Site Preference of Alloying Elements in DO22-Ni3V Phase: Phase-Field and First-Principles Study

Site preference of alloying elements in DO22-Ni3V phase was investigated using phase-field and first-principles method. The concentrations of alloying elements on sublattices of DO22-Ni3V phase were quantitatively studied using phase-field model based on microscopic diffusion equations. The phase-field computation results demonstrate that the concentration differences of alloying elements on the Ni-I and Ni-II site are attributed to the coordination environment difference. Host atoms Ni and substitutional ternary additions Al prefer to occupy Ni-I site. Antisite atoms V show site preference on the Ni-II site. Further reason of site preference of alloying elements on the two different Ni sites were studied using first-principles method to calculate the electronic structure of DO22-Ni3V phase. Calculation of density of states, orbitals population and charge population of the optimized Ni3V structure found that the electronic structures of Ni-I and Ni-II sites are different. Electronic structure difference, which is caused by coordination environment difference, is the essential reason for site selectivity behaviors of alloying elements on Ni-I and Ni-II sites.