Effects of CeO2 Content on the Microstructure and Mechanical Properties of ZK60 Mg Alloy

Abstract

This study primarily investigates the effect of CeO₂ content on the microstructure and mechanical properties of ZK60 Mg alloy. The results indicate that CeO₂ can be reduced by Mg to elemental Ce, predominantly in the form of the Mg-Zn-Ce phase. The addition of CeO₂ notably refines the grain size of as-cast ZK60 Mg alloy, with the Mg-Zn-Ce phase primarily distributed along grain boundaries. After extrusion, grain size increases and then decreases with increasing CeO₂ content, while the dynamic recrystallization (DRX) fraction gradually reduces. This behavior is chiefly attributed to the hindrance of the DRX process by a high density of second phases and the restriction of recrystallized grains growth by fine particles. The basal texture intensity increases progressively with the addition of CeO₂. As the CeO₂ content rises, the yield strength (YS) and elongation (EL) of the alloys show significant improvement. The increase in YS is mainly due to the combined effects of grain refinement strengthening and dispersion strengthening. In contrast, the enhanced EL is closely related to the heterogeneous structure of the grains. Notably, the ZK60-1.2CeO₂ alloy exhibits the ultimate tensile strength, YS and EL of 274 MPa, 160 MPa and 17.3%, respectively.