Effect of Ce Microalloying on Microstructure and Mechanical Properties of Extruded Mg–10Gd–0.5Zr Alloy

The influence of Ce microalloying (0.6 wt%) on the microstructure and strengthening mechanism of the extruded Mg–10Gd–0.5Zr alloy were comprehensively researched and analyzed. The experimental results revealed that the addition of 0.6 wt% Ce excellently reduced the grain size of the as-cast alloy and increased the amount of Mg₅Gd eutectic phase. The Ce microalloying promoted the dynamic recrystallization level of the extruded alloy, reduced the number and grain size of deformed grains, increased the number of dynamically recrystallized grains, and transformed the basal plane < 10 \(\overline{1 }\) 0 > fiber texture gradually into < 0001 > texture. Ce microalloying promoted the dynamic precipitation of a small amount of β-Mg₅Gd and α-Mg₁₂Ce particles. After peak aging, the Ce microalloying improved the aging response, increased the aging hardness of the alloy, promoted the aging precipitation of \(\beta^{\prime }\) phase, and enhanced the quantity and aspect ratio of \(\beta^{\prime }\) phase. The incremental tensile yield and ultimate tensile strength of the extruded alloy resulting from Ce microalloying are 14 MPa and 11 MPa separately, and those of the peak-aged alloy are 53 MPa and 34 MPa respectively. The increase in yield strength of the extruded and peak-aged alloy is ascribed to the enhanced grain boundary strengthening and the promotion of the \(\beta^{\prime }\) phase precipitation strengthening by Ce microalloying, respectively.