Theoretical calculations of the NiAl-NiTi phase diagram based on first-principles linear-muffin-tin-orbital and full-potential linearly-augmented plane-wave cohesive-energy calculations

Abstract

Linear-muffin-tin-orbital and full-potential linearly-augmented plane-wave calculations of cohesive energies were performed for observed and hypothetical ordered structures in the system NiAl-NiTi. Differences in cohesive energies were parametrized in both the Connolly and Williams and ɛ-G approximations, and the resulting effective-cluster interactions were used to calculate theoretical phase diagrams. Long-range ‘‘elastic’’ interactions and short-range e/Ieffective-cluster interactions are predicted to be causes of the observed immiscibility between B2 and L$2_1$ phases.