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

Alloy powder of an advanced gamma titanium aluminide alloy (gamma-TAB: Ti-47Al-4(Mn, Nb, Cr, Si, B) (at.%)) was produced by argon gas atomization. The fine powder (< 45 mum) was mixed with a special binder and test specimens were moulded. The specimens were debinded and subsequently sintered at 1410 degreesC. 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 mug g(-1), N-2: 140 mug 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 mug g(-1) (O-2) and 160-890 mug 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%. (C) 2002 Elsevier Science B.V. All rights reserved.