Effect of Au addition on the microstructure and mechanical properties of NiAl intermetallic compound

In this paper, the effects of Au on the microstructure and mechanical properties of NiAl intermetallic compound were investigated. The results showed that the addition of Au in the NiAl alloy refined the NiAl grains obviously, but more addition of Au resulted in the formation of α-AlAu2 phase in the alloy. The composition tests revealed that the Au had low solubility in NiAl about 0.3 at%. Au alloying had a moderate solid solution strengthening effect on NiAl at low temperature and a strong solid solution strengthening effect at high temperature. In addition, Au alloying improved the room temperature compressive ductility, elevated temperature strength and Vickers hardness of the NiAl alloy obviously. The room temperature fracture surface of Au doped NiAl alloys exhibited transgranular cleavage characteristics.