Effect of ZrO_2p on the Microstructure and Mechanical Properties of the AZ31 Magnesium Alloy

Magnesium matrix composites (MMCs), prepared by adding reinforcements to magnesium alloys, are widely noticed for superior properties over the matrix. However, few studies on ZrO_2p-reinforced AZ31 magnesium alloys were prepared by the powder metallurgy (PM) method. In this paper, AZ31 magnesium alloys with different ZrO_2p contents were successfully prepared by powder metallurgy (PM), and the microstructure and mechanical properties of AZ31 and MMCs were investigated. The results show that ZrO_2p hinders the migration of dislocations and forms a particle deformation zone (PDZ) around ZrO_2p. The PDZ with higher energy storage can promote the nucleation process of dynamic recrystallization of MMCs. Meanwhile, ZrO_2p pins the grain boundaries and hinders the growth of recrystallized grains, so the MMCs have higher recrystallization fractions and finer grains. In addition, the recrystallization process removes dislocation density and promotes the transition from low-angle grain boundaries to high-angle grain boundaries. As a result, the composites have superior properties due to the pinning of dislocations, grain refinement, and load transfer by ZrO_2p. Compared with the AZ31 matrix, the UTS, YS, and hardness of the MMCs were increased by ~ 6.8%, ~ 5.0%, and ~ 16.5%, respectively.