Gas atomized γ-titanium aluminide based alloys -: Processing, microstructure and mechanical properties

Ti gas atomization yields fine, almost segregation-free powders. It is increasingly used to produce Ti-intermetallics including a variety of gamma-TiAl based alloys. The gas atomized powders are consolidated by hot isostatic pressing (HIP) into fully dense compacts. In this study, powders of Ti-46/47Al-2Cr-2Nb with and without additions of 0.2 at% B have been produced. The powders are generally spherical with few satellites. They have a cellular microstructure with cell sizes of a few micrometers. The HIP-consolidated materials exhibit fine and isotropic microstructures without requiring thermo-mechanical treatment. Tensile properties of as-HIP and HIP plus heat treated materials are uniform throughout 13 by 24 cm (5" by 9.5") compacts due to their homogeneous composition and isotropic microstructure. The HIP + heat treated Ti-47Al-2Cr-2Nb exhibits a yield strength of 435 MPa and a ductility of 1.5 %. The as-HIP Ti-46Al-2Cr-2Nb-0.2B shows better properties with a yield strength of 460 MPa and a ductility of 3%.