Physical metallurgy of titanium aluminides

Abstract

for becoming some of the most important aerospace materials because of their low density, high melting temperature, good elevated temperature strength and modulus retention, environmental resistance, and excellent creep properties. One of the chief roadblocks to their applications is their poor_ductility at low to intermediate temner&turea resulting in low fracture toughness and fast fatigue crack growth rate. During the last several years a great deal of effort has been made to improve the ductility, with some success, through chemistry modification and microstructure control. This paper reviews overall properties of alpha_2 allows and mamma, alloys such as crystal 'striicture, phase relations, _processing/microstructure relations, deformation mechanisms, mechanical properties, effect of interstitials, and environmental effects. An extended discussion will be made on how parameters such as alloy composition, phases present, and microstructure influence the ductility of gamma alloys