Effect of Hot-Forging Process on Microstructure and Micro-hardness of AZ31/Al2O3 Nanocomposites

Magnesium matrix nanocomposites have been recently studied as a noteworthy choice for engineering applications due to their low density and high specific properties such as strength, stiffness, and creep resistance. Among all different methods available for metal matrix composite production, stir casting is considered as a common and relatively low cost method. Since the materials produced by casting process are not dense enough, they are usually subjected to a secondary bulk forming process, which could improve their mechanical and microstructural properties and also be used to manufacture the final products. In this regard, forging is noticeable due to its advantages such as lower operating stresses and less damage to the reinforcing phase. In this paper, AZ31/Al2O3 nanocomposite has been fabricated using stir casting method. Then, open-die hot-forging process has been implemented on the specimens. Next, microstructure and microhardness of the specimens were investigated by optical microscopy and Vickers microhardness test, respectively. The results show that hot-forging process affects the microstructure in the both AZ31 and AZ31/Al2O3 nanocomposite specimens, although the composite has more uniform microstructure. Moreover, microhardness of the forged-composite depends on the amount of plastic strain and has been increased in comparison to non-reinforced alloy.