First principles electronic structure calculations, using the layer Korringa-Kohn-Rostoker method, are reported for isolated planar faults in TiAl. The calculated fault energies are discussed in the context of suggested superdislocation separation reactions. The influence of dilute impurities on fault energies are treated using the coherent potentialapproximation. Using this approach, the variation of fault energies in TiAl resulting from stoichiometry changes and from the addition of Mn axe calculated, and compared to recent experimental data.

Electronic Structure of Planar Faults and Point Defects in High Temperature Intermetallics

The authors discuss the application of the first-principles Korringa-Kohn-Rostoker coherent potential approximation to the calculation of the electronic structure of substitutionally disordered alloys with layer geometries (surfaces, interfaces etc)-the LKKRCPA. The canonical problem of this type is that of a single layer of a random binary alloy, and they present results for a Cu0.5Pd0.5 monolayer. They compare the effective scattering amplitudes and average densities of states with those of the bulk FCC alloy, and comment on the significance of the result for the surface electronic structure of Cu-Pd alloys. They outline how disordered layers may be embedded onto or between bulk substrates in order to treat real alloy surfaces or interfaces.

J H Kaiser

Papers

Electron states in disordered layers