Thermodynamic and mechanical stability of Ni3X-type intermetallic compounds

Ni3X-type intermetallic compounds, also often referred to as γ′, γ″, and η precipitates in Ni-base alloys, have been investigated by first-principles methods. Thermodynamic and mechanical stability of Ni3X (X = Al, Ti, Nb, Mo, Fe, and Cr) compounds has been determined by density functional theory calculations of formation enthalpies and elastic properties of their L12, D022 and D024 phases. In addition, we have investigated the site preference behavior of Al, Ti, Nb, Mo, Fe, and Cr solutes in the L12-structure Ni3Al, Ni3Ti, and Ni3Nb intermetallic compounds and used this information to investigate the solubility of the aforementioned alloying elements. Our results show that the most stable structures of Ni3Al, Ni3Ti, Ni3Nb, Ni3Cr, Ni3Mo, and Ni3Fe at 0 K are L12, D024,D022, D024, D022, and L12 respectively. [Display omitted] •The phase stability of Ni3X (X = Al, Ti, Nb, Mo, Fe, Cr) has been investigated.•Ni3Ti has been identified as the most stable compound.•Site occupancy and solubility of solutes in L12-Ni3X has been studied.