Effect of Ti, Ta, Nb on structural transformation of Ni3Al in terms of stacking faults

This study explored the structural stability, elastic properties, structural transformation, and critical concentration of Ni3Al and Ni3M (M = Ti, Ta, Nb) using L12, D024, and DO22 structures, along with three-dimensional supercells featuring stacking faults along [101] , [011] , [111] directions. First-principles calculations revealed that the most stable structures for Ni3Al, Ni3Ti, Ni3Ta, and Ni3Nb are L12, D024, DO22, and DO22, respectively. Notably, the bulk modulus, Young′s modulus, shear modulus, and isotropy of Ni3Ti, Ni3Ta, and Ni3Nb surpassed those of Ni3Al, with increased ductility, except for Ni3Ti. By substituting Al atoms with 0–8 Ti, Ta, and Nb atoms in a 32-atom Ni3Al structure, the critical concentration for the transformation from L12 to D024 or DO22 ranged between 18.75 at.