Microstructure and mechanical properties of a novel TiNi particulate reinforced AZ91 metal matrix composite

A new AZ91/TiNi composite has been developed in the present study. The composite containing 20% (vol.) TiNi reinforcement micro-particles was produced by hot pressing of initial prealloyed AZ91D and Ti49.2Ni50.8 powders at 420 °C for 1 h. Microstructural analysis revealed that matrix and reinforcement phases did not react each other during processing and a good bonding which is free from porosity, oxide and carbides was attained. Ti49.2Ni50.8 reinforcement increased room temperature yield strength, compressive strength and ductility of AZ91D alloy 5%, 50% and 30%, respectively. Most importantly, yield strength of the composite at 100 °C was found to be 267 MPa, 50% higher than that of AZ91D alloy (176 MPa) due to stress-induced martensitic transformation observed in the reinforcing alloy.