Flow stress behaviour and microstructural analysis of hot deformed Aluminium matrix composites reinforced with CuZnAlNi shape memory alloy particles

The compressive flow stress behaviour and microstructures of hot deformed Al alloy matrix composites (AMCs) reinforced with CuZnAlNi based shape memory alloy (SMA) particles was investigated. Al-Mg-Si based alloy, reinforced with 4, 6, and 8 wt.% Cu-18Zn-7Al-0.3Ni, and 8 wt.% SiC particles, were produced by double stir casting and subjected to hot compression testing at 1.0 s^-1 strain rate, 400 °C temperature, and ~ 60% constant global strain using a Gleeble 3500 thermomechanical simulator. The starting and as-deformed microstructures of the composites were examined using optical microscopy. The use of Cu-18Zn-7Al-0.3Ni particles as reinforcement resulted in the development of finer matrix structure compared with the use of SiC. The flow stress and hardness of the AMCs reinforced with Cu-18Zn-7Al-0.3Ni particles were generally higher than that of the unreinforced Al alloy and the SiC reinforced Al alloy. Also the flow stress, and to a large extent the hardness, increased with increase in the weight percent of Cu-18Zn-7Al-0.3Ni particles in the AMC. The improvement observed with the use of Cu-18Zn-7Al-0.3Ni alloy particles was ascribed to the combination of enhanced matrix grain refinement strengthening, interfacial strengthening, compressive residual stresses, high thermal conductivity, and damping capacity offered by the Cu-18Zn-7Al-0.3Ni alloy.