Tailoring deformation mechanisms via minor Ce to improve the tension–compression yield asymmetry of Mg-Ca-Mn alloy

The tension–compression yield asymmetry (TCA) of magnesium (Mg) alloys is intrinsically governed by the competition between twinning and slip during plastic deformation. In this study, minor Ce element was introduced into a Mg-Ca-Mn alloy to modify its deformation mechanisms and thereby improve its TCA. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and viscoplastic self-consistent (VPSC) modeling were employed to characterize the microstructure and deformation behavior. The results indicate that the addition of Ce promotes the formation of Mg 41 Ce 5 phase, which enhances particle-stimulated nucleation and Zener pinning effects, leading to significant grain refinement from 3.04 μm to 1.73 μm. During uniaxial tension parallel to the extrusion direction (ED), the Ce addition enhances the activity of non-basal slip, thereby enhancing strain compatibility and plasticity of the alloy. In contrast, under uniaxial compression parallel to the ED, grain refinement and RE texture effectively suppress the activation of {10–12} extension twin, while Mg 41 Ce 5 precipitates hinder their propagation and thickening. Consequently, twinning activity is markedly reduced, resulting in a substantial increase in compressive yield strength. Overall, the Ce addition effectively reduces the activity gap between non-basal slip and {10–12} twin, thereby improving the TCA of the Mg-Ca-Mn alloy from 0.74 to 0.84.