Microstructure characteristics and mechanical properties of NiAl/Cr(Hf, Ho) in situ composite

Abstract

Minor hafnium and holmium were added in the NiAl/Cr in situ composite and their effects on microstructure evolution and mechanical properties were studied. The results reveal that minor holmium can refine the eutectic lamella inside eutectic cell and precipitating phase in intercellular zone. Furthermore, holmium addition causes the precipitation of Ni₂Al₃Ho and Ni₁₇Ho₂ phases, which have the orientation relationships of , , and . Additionally, with the holmium addition, the amount of Heusler phase increases and the precipitates in eutectic lamella become coarsening. Mechanical properties exhibit that appropriate addition of hafnium and holmium can increase the strength and hardness of the composite.

Keywords:

• NiAl/Cr in situ composite
• Microstructure
• Precipitation
• Transmission electron microscopy
• Mechanical properties