Effect of element Ce on the strain rate sensitivity of Mg-Zn-Zr alloy

• The strain rate sensitivity of different alloys is compared in a new perspective. • Through the analysis of the relationship between yield strength and strain rate by thermal activation theory, the main reason for the difference in strain rate sensitivity is identified as the difference in deformation mechanism. • There are differences in the absorbed energy density (Δ E ) and the adiabatic temperature rise (Δ T ) of different alloys under the same strain rate. This makes it easier for the Ce-containing ZK60 alloys to produce dislocations prone to higher density, or even to initiate 〈 c + a 〉 dislocation under the same deformation conditions, which is the fundamental reason for its high strain rate sensitivity. Investigations into the strain rate sensitivity of magnesium (Mg) alloys represent a current research focus in materials science. However, most studies have examined strain rate sensitivity in single alloy, lacking systematic comparisons between different alloys. In the present study, a series of ZK60-xCe ( x = 0, 0.3, 0.8, 1.3) alloys were fabricated via hot extrusion deformation. The microstructure evolution and strain rate sensitivity of these alloys under dynamic compressive loading were systematically investigated. According to thermal activation theory calculations, the strain rate sensitivities of ZK60-xCe alloys are predominantly governed by their deformation mechanisms. The enhanced strain rate sensitivity observed in Ce-containing ZK60 alloys is primarily attributed to their high dislocation density. This correlation stems from two key factors: (1) Ce-containing alloys demonstrate significantly higher Δ E and Δ T values compared to the base ZK60 alloy, providing the necessary energy conditions for high-density dislocation generation; and (2) the Ce addition effectively promotes 〈 c + a 〉 slip activation and facilitates cross-slip behavior. It is hoped that this work can provide a new perspective for the study of strain rate sensitivity in Mg alloys and offer a methodology for comparing strain rate sensitivity among different alloys.