Microstructures and properties of extruded TiAl-Nb-W alloys

Three Ti-46Al alloys containing 4 to 8 at. % Nb were produced by nonconsumable-arc melting into 25-mm-diam ingots. The ingots were hot-extruded at 1350degreesC (similar to35 to 50degreesC higher than Talpha) in a steel can to a reduction ratio of 10:1. The extruded bars were machined into tensile bars and tested at RT, 500, and 800degreesC in the as-extruded condition. Optical microstructures were examined in the as-extruded condition and after stress-relieving and annealing treatments at 1000degreesC/2 h and 1315degreesC/20 min. Tensile data were compared with data reported in literature on alloys of similar compositions and processing conditions. The three alloys are promising possibilities in that they show superior tensile properties in this comparison which is emphasized by the leanest TiAl-46Al-4Nb-1W-0.12B alloys, when tested in the as-extruded condition.