FLEXURAL STRENGTH OF GAMMA-BASE TITANIUM ALUMINIDES AT ROOM AND ELEVATED-TEMPERATURES

The influences of microstructure, alloying additions and processing method on the flexural strength and fracture behavior of gamma base titanium aluminides were investigated at room and elevated temperatures. The flexural strength strongly depends on the microstructure, alloying addition and processing method. The lamellar microstructure material exhibited high strength and ternary chromium or niobium addition improved the strength. Isothermal forging resulted in a fine grain microstructure and influenced the bend properties. The flexural strength increased up to a 'critical temperature' and thereafter it decreased. This 'critical temperature' seemed to depend on the chemical composition. The room-temperature fracture was mostly transgranular cleavage and intergranular fracture regions were dominant with increasing temperature. At high temperatures ductile tearing was observed, irrespective of the microstructure.