Evaluation of the Effects of SiCp on Hot Deformation Behavior and Microstructure of AZ61 Magnesium Alloy

The AZ61 magnesium alloys are widely used in the automobile industry for load-bearing component applications due to their high strength-to-weight ratio. In this study, the effects of the incorporation of silicon carbide (SiCp) particles on the microstructure and hot deformation behavior of an AZ61 alloy fabricated by the stir casting process were studied. Investigation of the fabricated composite was carried out using the hot compression process under different deformation conditions (temperatures (280, 320, 360, 400, and 440 °C) and strain rates (0.001, 0.01, 0.1, and 1 s−1)). A constitutive equation was developed using the flow stress at a strain rate of 1.2. The results indicate that the predominant mechanism affecting the AZ61 alloy was dynamic recrystallization (DRX) arising from the dislocation climb. The microstructure of the AZ61/SiCp composite could be controlled by the process of DRX through particle stimulated nucleation due to the dislocation climb. Processing maps were developed to determine the workability parameters of the fabricated materials by examining the power dissipation efficiency and instability parameters. The processing maps revealed the workability domain to occur at a temperature of 440 °C and a strain rate of 0.001 s−1 for both the alloy and the composite. However, the AZ61/SiCp composites showed the maximum power dissipation efficiency (39%) and no instability region compared with the AZ61 alloy (38%). Therefore, the AZ61/SiCp composite has much better workability than the AZ61 alloy. There is good agreement between the typical microstructure, as illustrated by the processing map, and the findings of the microstructure measurements.