In this study, first, the microstructure and mechanical properties of AZ80 magnesium alloy and SiC/AZ80 nanocomposite were compared. Then, the effects of 1, 3, and 5 passes of repeated upsetting (RU) process performed at 300 C on the nanocomposite were investigated. According to the optical microscopy images, the average grain size in AZ80 alloy is 60.3 lm, which has decreased to 30.6 lm as a result of adding SiC nanoparticles. After the fifth pass of RU process, the average grain size reaches its minimum value as 4.5 lm with a homogenous structure. The shear punch test was run to measure the shear strength of the samples. The results showed shear yield stress and ultimate shear strength, which were 111.2 and 145.2 MPa in AZ80 alloy, respectively, increasing to 150.6 and 181 MPa in nanocomposite after five passes of RU process. Also, mixed-mode fracture tests show that fracture toughness in mode I and the mixed-mode significantly increased as a result of adding the SiC nanoparticles and RU process. Following a decrease in grain size and improvement in strength, the surface hardness was elevated from 79.9 HV in AZ80 alloy to 96.2 HV in RUed nanocomposite. These results indicate that the RU process, which is capable of manufacturing thick samples, can improve the microstructure, shear strength, fracture toughness, and hardness of SiC/AZ80 nanocomposite.
