Enhancing Strength-Ductility Synergy in Rolled High-Thermal-Conductivity Mg-Mn-Ce Alloys via Accumulated Strain

Magnesium (Mg) alloys are prized as the lightest structural materials but often suffer from a strength-ductility trade-off that is particularly challenging for applications demanding high thermal conductivity. Aiming to resolve this issue, rolled ternary Mg-0.9Mn-1.9Ce (wt.%) alloy sheets were designed and fabricated, and the influence of rolling strain on optimizing the property balance was systematically investigated. The cast alloy was homogenized and rolled to two accumulated strains to obtain S10 (90%) and S20 (95%), followed by microstructure characterization and mechanical/thermal evaluation. Compared with S10, S20 developed finer, more equiaxed grains and a weaker basal texture via enhanced dynamic recrystallization; concurrent fragmentation and uniform dispersion of second-phase particles further contributed to strengthening. Consequently, S20 achieved 14.2% and 13.7% increases in yield and tensile strengths, respectively, with a slight improvement in elongation, while retaining high thermal conductivity (134.4 W·m^-1·K^-1 vs. 138.1 W·m^-1·K^-1 for S10). The minimal conductivity penalty is attributed to the low solute level in the α-Mg matrix, which limits electron scattering. These results provide experimental and mechanistic guidance for developing rolling Mg alloys that combine high mechanical performance with excellent thermal efficiency.