The effect of microstructure on the creep behavior of the Ti-46Al-1Mo-0.2Si alloy

The influence of the microstructure on the creep properties of a Ti-46.8Al-1Mo-0.2Si was studied by stress change tests in compression at temperatures ranging from 700 to 1000 °C. The material produced by arc melting exhibited a structure of coarse lamellar grains in the as-cast condition that transformed to an equiaxed near γ microstructure after processing by hot extrusion at 1300 °C. The high temperature deformation data strongly depended on the type of microstructure present in the material. For each microstructure, deformation data were correlated by means of a conventional power law creep relation. The analysis showed an activation energy of about 400 kJ/mol for both microstructures. On the other hand, each starting microstructure showed a different stress exponent. TEM analysis of deformed samples allowed the correlation of the stress exponents to different mechanisms controlling deformation.