Phase Stability, and Cohesive, Electronic and Mechanical Properties of Intermetallic Compounds

Current sophisticated electronic structure simulations are at the forefront of understanding and predicting a variety of materials properties of intermetallic compounds. Several examples are given here that illustrate how first principles total energy local density methods have addressed the problems of (i) phase stability and the effect of ternary additions, (ii) anti-phase boundaries (APB’s) in B2 NiAl, FeAl and RuAl aluminides and other faults in determining their structural and bonding character. A key objective has been to attempt to understand, at the electronic level, fundamental quantities that may be related to the crucial ductility issue in high temperature intermetallics. Differences between observed ductility properties of related systems may relate to their differing electronic and bonding properties, particularly the nature of p-d hybridization and the directional charge distributions of the states near the Fermi energy.