Electronic Structure of Planar Defects in Ordered and Disordered High Temperature Intermetallics

Abstract

In this paper self-consistent electronic structure calculations are reported for isolated planar faults in the intermetallic alloy TiAl. The electronic structure calculations for planar faults in ordered stoichiometric TiAl have been performed using the layer Korringa-Kohn-Rostoker method. Calculations for off-stoichometric TiAl, and TiAl alloys with varying compositions of Cr and Mn were performed using the layer Korringa-Kohn-Rostoker method combined with the coherent potential approximation. The most dramatic reductions in fault energies are observed for Mn substitutions. Cr substitutions, however, produce similar changes in fault energies as Ti does. These results are discussed in terms of experimental observations for TiAl.