The influence of alloying modifications on mechanical properties, phase stability, and fault energies in cubic titanium trialuminide-based alloys

The cubic titanium trialuminide alloys studied previously show limited ductility and toughness, which can be related to the difficulties of dislocation emission, multiplication and mobility and to the excessively high energies of faults associated with the dislocations. The present study examines several new alloys chosen in an attempt to reduce these fault energies and thereby improve the mechanical properties. The region of single phase L1 2 material is unfortunately so limited that only minor changes in composition are possible before second phases form and precipitation hardening occurs. Over the range of compositions of the L1 2 phase evaluated there are generally only small changes in fault energies. These changes, as well as the changes in dislocation configurations seen, may be rationalized in terms of the instability of the matrix towards the particular second phase forming.