Hot deformation and processing maps of Al 18B 4O 33w/ZK60 composite

Abstract

The hot deformation behavior of ZK60 magnesium alloy reinforced with 20 vol.% of Al 18B 4O 33 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 Al 18B 4O 33w/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 Al 18B 4O 33w/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.