Abstract
The present paper deals with the occurrence and magnitude of characteristic mechanical anomalies observed in many L12 intermetallic compounds and their relation to the phase stability of the crystal structure against other geometrically close packed (GCP) phases. The dislocation configurations in the crystal structure and resultant plastic behavior are in close relation with anti-phase boundary (APB) and stacking fault (SF) energies in the compounds, while the relative magnitude of these energies on various crystallographic planes actually determines the phase stability of the L12 crystal structure. It is shown here, based on our series of investigations carried out over the past decade, that the general tendencies for particular deformation modes to occur can be systematically interpreted in terms of alloy chemistry of the compounds, including variables such as combination of component species, nonstoichiometry and ternary additions in the compounds, all of which affect the stability of the phase.
