Hot deformation and processing maps of Al18B4O33w/ZK60 composite

The hot deformation behavior of ZK60 magnesium alloy reinforced with 20 vol.% of Al18B4O33 whisker has been studied by employing both processing maps and microstructural observations. The material of investigation was deformed by compression in the temperature range of T = 523–723 K and strain rate range of ε˙=0.001−10 s−1. From the hot compression tests, the flow stress data, strain rate sensitivity index (m), power dissipation efficiency (η  ) and instability parameter (ξ(ε˙)) were evaluated and processing maps were developed for the strain of ɛ = 0.6. Domains for optimum hot working conditions were obtained using the processing maps and the instability zones were identified. The material showed a regime of dynamic recrystallization in the temperature range of T = 623–723 K and strain rate range of ε˙=0.001−0.1 s−1 corresponding to the higher values of efficiency (η). The optimum temperature and strain rate combination for squeeze cast Al18B4O33w/ZK60 composite are T = 673 K and ε˙=0.1 s−1 corresponding to an efficiency of η = 24%. In the temperature range of T = 573–623 K and strain rate range of ε˙=0.001−0.01 s−1 Al18B4O33w/ZK60 composite exhibited dynamic recovery. At the strain rate higher than 0.3 s-1 and temperature range of T = 623–723 K, the material exhibited flow localization and these conditions should be avoided in processing.