Development of high Nb containing high temperature TiAl alloys

Gamma-TiAl alloy have been developed into two categories: conventional TiAl and high temperature TiAl (High Niobium containing) alloys. These state-of-the-art alloys have great advantage that the service temperature is 60-100 DGC higher than that for conventional TiAl alloy. The relations between composition, microstructure and properties for high temperature TiAl alloys have been shown in the paper, including the quasi-binary phase diagram with high Nb contents, the high temperature strengthening mechanisms of Nb, Al and other elements, microstructure stability and degradation at high temperature, the creep property improvement and its relations with microstructure parameters. The paper also indicates further development of high temperature TiAl alloys. (AU)