Microstructures and properties of investment castings of γ-titanium aluminide

γ-TiAl castings have been produced by induction skull melting (ISM), and their microstructures, hardness and tensile properties have been studied in the as-cast, hot isostatically pressed (HIPped) and HIPped+heat treated conditions. The equiaxed rosette grains found in the cast structure suggest that the alloy was cast in a partially solid condition. HIPping and heat treatment for 24 h at 1300 °C resulted in a duplex structure and decreased the hardness and tensile properties compared with the as-HIPped condition. The hardness and tensile properties also decreased with increasing bar diameter. The main fracture modes in duplex structures were transgranular (TG) in equiaxed γ-grains and translamellar (TL) in lamellar grains. The presence of an α2/γ lamellar structure can improve strength and ductility.