Comparing the microstructural and mechanical improvements of AZ80/SiC nanocomposite using DECLE and MDF processes

Abstract

The present study investigates the effects of two different severe plastic deformation (SPD) processes on an annealed AZ80/SiC nanocomposite. Specifically, the microstructure, texture, shear behavior, and hardness of the material were analyzed after being subjected to dual equal channel lateral extrusion (DECLE) for up to 5 passes, and multidirectional forging (MDF) for up to 8 passes, both carried out at a constant temperature of 300 °C. The effective strain was 1.44 and 0.5 in each DECLE and MDF pass. The annealed AZ80/SiC nanocomposite showed a reduction in average grain size from 68.4 μm to 2.7, 4.2, and 4.4 μm during 1, 3, and 5 passes of DECLE process, and to 8, 4.3, 2.3, and 5.4 μm during 2, 4, 6, and 8 passes of MDF process. Examination of the shear properties revealed that the ultimate shear strength (USS) of the nanocomposite increased after conducting both the DECLE and MDF processes. Specifically, the USS of the annealed nanocomposite increased by 23.1 MPa after 5 passes of the DECLE process and by 8.1 MPa after 8 passes of the MDF process. These results indicate that the DECLE process had a greater effect on the shear strength increase compared to the MDF process. The results of the hardness testing on the AZ80/SiC nanocomposite showed that the fifth pass of the DECLE process increased the hardness from 86.6 to 96.2 Hv, while the eighth pass of the MDF process increased this value to 90.1 Hv. The DECLE process was found to be more effective than the MDF process due to the simultaneous application of three types of shear deformation, pressing, and extrusion in each pass, as well as the higher effective strain.