Understanding and Exploitation of Alloys Based on the Compound TiAl (Gamma Phase)

摘要

Alloys based on the TiAl (Gamma) phase have attractive elevated temperature properties for gas turbine applications. However, certain processing and property problems will have to be overcome before such materials are qualified for the projected applications. The work performed addressed two such problem areas. In Phase A, an extensive alloy development effort was conducted in which the effect of single and multiple elemental additions on the microstructure and mechanical properties of various TiAl base compositions was studied in order to overcome the low ductility at room and intermediate temperature. It was shown that the best balance of tensile ductility and creep-rupture strength is achieved when the aluminum content is about 48 atomic percent. Two other positive compositional effects were demonstrated. One is the increase in ductility at room and intermediate temperature imparted by vanadium additions; the second, a large increase in creep-rupture strength resulting from the addition of 0.1 percent carbon to a Ti-Al-V base.