Fabrication and Properties Assessment of HIPped Gas Atomised Titanium Aluminides

摘要

Titanium aluminide alloys have a considerable potential for use in advanced turbine engine applications in regards to their attractive properties (low density, high specific modulus, high temperature strength, oxidation and burn resistance). The inherent poor ductility at room temperature of titanium aluminides can be balanced owing to a best control of it conferred by powder metallurgy (P/M). Homogeneous and isotropic microstructures and properties are obtained by hot isostatic pressing (HIP) of Gas atomised powders. In this study, Gas atomised powders corresponding to a Ti-48Al-2Cr-2Nb composition are fully consolidated (P/M samples are free of porosity) by HIP and heat-treated at various temperatures. The effects of HIP and heat treatment on the microstructure and tensile, fatigue and creep properties are discussed. A particular emphasis on the fatigue strength resistance related to different microstructural defects is approached. Then conclusions concerning future potential engine applications are tackled.