HIGH-TEMPERATURE STRENGTH AND FRACTURE-TOUGHNESS IN GAMMA-PHASE TITANIUM ALUMINIDES

High-temperature strengths and fracture toughnesses of gamma-phase titanium aluminides were estimated at room and elevated temperatures. The effects of chromium on these mechanical properties were investigated. It was found that addition of chromium substantially improved the room- and high-temperature strength and toughness of the binary titanium aluminides. The transition temperature at which the strength drops was found to increase due to the addition of chromium. The fracture behaviour of binary and chromium-alloyed titanium aluminides were investigated. The fracture mechanism was affected by the addition of chromium. Ductile tearing was observed for the ternary material at 800-degrees-C, and this was delayed for the binary material.