Application of tight-binding electronic theory to phase stability and mechanical properties of intermetallic compounds

Abstract

The phase stability and mechanical properties of ordered intermetallic compounds are investigated using the tight-binding (TB) electronic theory. The authors use the semiempirical TB method (for the lattice-relaxation calculations), as well as the first principles TB-LMTO approach based on the density-functional theory. The authors focus their attention on the strength anomaly in IVa-VIII intermetallic compounds with B2 structure. It has been shown experimentally that CoTi, CoZr, and CoHf display the positive temperature dependence of yield stress at intermediate temperatures while FeTi does not have their characteristics, depending on the position of the alloying elements in the periodic table. The observed strength anomaly operating at intermediate temperatures is discussed in conjunction with the relative phase stability of B2 structure with respect to Bf or B19 phase and dislocation core structures.