Microstructure and phase solubility extension in injection cast NiAl-28Cr-5.7Mo-0.3Hf alloy

The NiAl-28Cr-5.7Mo-0.3Hf eutectic alloy was fabricated by injection casting to investigate the effect of rapid solidification on the microstructure, solubility expansion and hardening mechanism of the alloy. The results showed that the forming ability of injection casting was quite poor owing to the near eutectic composition of the present alloy; the microstructure of injection cast alloy presented a fine microstructure under the condition of rapid solidification. In addition, the extension of solid solubility occurred in the alloy. The microstructure change and the solubility expansion are attributed to the increase of solidification rate. The microstructural refinement and solubility expansion contribute to the hardening of the injection cast alloy jointly.