Microstructure and mechanical properties of NiAl–Cr(Mo)/Hf alloy prepared by injection casting

In the present paper, the microstructure, compressive properties at different temperatures and hardness of NiAl–Cr(Mo)/Hf alloy prepared by injection casting were investigated. Compared with the conventionally-cast alloy, the injection-cast alloy exhibited a fine microstructure, i.e. the fine eutectic cell and interlamellar spacing as well as fine primary NiAl phase and Heusler phase Ni2AlHf due to the high cooling rate. In addition, the area fraction of primary NiAl phase at the cell interior or cell boundaries and eutectic cell increased. The ductility and yield strength at room temperature increased by about 100% and 25% over those of conventionally-cast alloy respectively. However, both alloys possessed the similar high temperature strength. The Vickers hardness of injection-cast alloy also increased markedly.