Entropy favored ordering: Phase stability of Ni 3Pt revisited by first-principles

Abstract

Ni 3Pt holds great importance for the development of new thermal barrier coatings and Ni-base superalloys. Considerable experiments and cluster expansion predictions based on first-principles calculations lead to a long-standing belief that the ground state of Ni 3Pt is the γ′ phase with L1 2 structure. In contrast to this belief, our first-principles calculations predict that the ground state of Ni 3Pt at 0 K is the ferromagnetic γ″ phase with DO 22 structure. Based on first-principles phonon calculations, we find that the phase stability between γ′ and γ″ can be reversed around 413 K mainly due to the vibrational entropy.