Mechanical performance of extruded Ti-46Al-5Nb-1W titanium aluminide

Titanium aluminide alloys offer considerable promise for use in high temperature applications, such as gas turbines. In this study an extruded Ti-46Al-5Nb-1W alloy has been examined, in terms of its tensile and creep behaviour. A reasonably fine and uniform microstructure was found in this bar product. This gave excellent properties, with tensile strengths up to ~950 MPa at room temperature, along with 1% elongation. These properties were accompanied by a very good creep behaviour, with low primary strains at the lower stresses and very low secondary creep rates. Comparison of the creep properties of this titanium aluminide alloy with other similar compositions and some typical nickel alloys shows that it is significantly superior to first generation titanium aluminides but also nickel alloys, such as IN718 and Udimet 720Li. However, the strain controlled fatigue performance of the titanium aluminide alloy was significantly poorer than these same wrought nickel alloys. [PUBLICATION ABSTRACT]