A multiphase NiAI-28Cr-5.85Mo-0.15Hf alloy, which was directionally solidified (DS) in an AI2O3-SiO2 mold by stan-dard Bridgman method and then underwent prolonged solution and aging treatment was prepared. The microstruc-ture, tensile properties as well as tensile creep of the heat-treated alloy at different temperatures were studied. Thealloy was composed of NiAl, Cr(Mo) and Hf-rich phase and small amount of fine Heusler phase (Ni2AIHf). Althoughthe present alloy exhibited high tensile strength at low temperature, it was weaker than that of system with highcontent Hf but still stronger than that of many NiAI-based alloys at high temperatures. The fracture toughness islower than that of DS NiAI-28Cr-6Mo alloy. Nevertheless, advantageous effects on the mechanical properties, i.e.the decrease in brittle-to-ductile transition temperature (BDTT) were obtained for the low content of Hf. The ob-tained creep curves exhibit conventional shape: a short primary creep and long accelerated creep stages. The ruptureproperties of the heat-treated alloy follow the Monkman-Grant relationship, which exhibits similar creep behavior tothat of NiAI/Cr(Mo) system with high Hf content.
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