Strength and ductility enhancement of AZ61/Al2O3/SiC hybrid composite by ECAP processing

Abstract

Magnesium is a low-density metal which is used in extensive structural applications such as load-bearing components in the automobile industry. To improve the strength and ductility of the magnesium alloys, method of production of metal matrix composites have been developed. In this study, AZ61 magnesium alloy was reinforced with hybrid particles (2 wt% Al2O3 and 1 wt% SiC) fabricated by the stir casting method. Then, the casted samples were homogenized at 410 °C for 24 h, aged at 200 °C for 10 h followed by severe plastic deformation (SPD) processing using equal channel angular pressing (ECAP). The obtained microstructure observation showed that the hybrid reinforcement particles were uniformly distributed in the metal matrix. After the ECAP process, the grain size was significantly reduced from 148.79 ± 79 µm to 12.2 ± 8 µm due to the dynamic recrystallization (DRX) mechanism during the plastic deformation. The mechanical properties of hardness, yield strength (YS), ultimate tensile strength (UTS), and elongation are effectively improved after each ECAP pass; the maximum values achieved were 61.2 ± 4.6 HV, 110.3 MPa, 250.1 MPa, and 19.3%, respectively on the AZ61/Al2O3/SiC hybrid composite subjected to two passes of ECAP. The enhancement of the mechanical properties of the AZ61 hybrid composites was mainly attributed to the Hall-Petch strengthening mechanism.