Prospects for metal injection moulding using a gamma titanium aluminide based alloy powder

Abstract

Alloy powder of an advanced gamma titanium aluminide alloy (γ-TAB: Ti–47Al–4(Mn, Nb, Cr, Si, B) (at.%)) was produced by argon gas atomization. The fine powder (<45 μm) was mixed with a special binder and test specimens were moulded. The specimens were debinded and subsequently sintered at 1410 °C. The porosity after sintering was about 3.8%. Subsequent hot isostatic pressing (HIP) caused a further reduction in porosity to 0.4%. While the fine alloy powder had low oxygen and nitrogen levels (O 2: 790 μg g −1, N 2: 140 μg g −1), the sintered and HIP'ed samples are characterized by a considerable increase in O 2 and N 2. Both types of impurities vary in the depth of the samples in the range of 1600–8000 μg g −1 (O 2) and 160–890 μg g −1 (N 2). After HIP the microstructure is of duplex type. Tensile tests at room temperature resulted in a yield strength of 410 MPa, an ultimate tensile strength of 430 MPa and a plastic elongation of 0.6%.