Abstract:

The precipitations and high temperature tensile strength of DS NiAl/Cr(Mo,Hf) alloy after the HIP and aging treatment were studied. The experimental results showed that the NiAl and Cr(Mo) eutectic phases were stable, while the Heusler phase, which distributed at the NiAl/Cr(Mo) interface in the as-cast alloy, reduced greatly and redistributed in the NiAl and Cr(Mo) phase. It was also found that the Heusler particles mainly precipitated at the NiAl/Cr(Mo) interface and NiAl grain boundaries and the reason of which was interpreted from the viewpoint of interfacial energy. The G-phase also disappeared in the HIPed and aged specimen. The tensile experiments showed that the strength of the alloy is higher than that of most NiAl-based alloys.

Key words: hotiso static pressing, heusler phase (Ni₂AlHf), G (Ni₁₆Hf₆Si₇), mechanical property