Metal injection moulding of gamma titanium aluminide alloy powder

Fine alloy powder with the nominal composition Ti 47Al 4(Mn,Cr,Nb,Si,B) (at%) has been produced by argon gas atomization and processed by metal injection moulding. The main objective of process optimization concerned the level of the impurity pick-up and the influence of sintering atmosphere on porosity and microstructure. The evaporation of Al during sintering can be controlled by varying the gas pressure of the Ar atmosphere. Impuritiy levels around 1350 μg/g (O), 90 μg/g (N) and 350 μg/g (C) were achieved. During sintering, a near gamma microstructure with average gamma grain size around 12 μm is obtained. Tensile tests were conducted at RT using as-sintered samples and additionally HIP’ed test specimens. The results are discussed considering the properties of samples with comparable composition and microstructure manufactured by HIP of alloy powder and subsequent annealing.