Regulation of Secondary Phases in Mg-Sn-Zn-Ca Alloys Through Incremental Temperature Rolling and Their Performance

Abstract:

To investigate the effect of secondary phases on the microstructure and mechanical properties of Mg-Sn-Zn-Ca alloys, this study employed both isothermal and incremental temperature rolling processes on Mg-2Sn-2Zn-1Ca magnesium alloy sheets. Mechanical tests reveal that the yield strength (161.3 MPa) and elongation (6.6%) of the isothermally rolled sheet are significantly lower than those of the incremental-temperature-rolled sheet, which exhibits a yield strength of 295.6 MPa and an elongation of 20.9%. Microstructural analyses indicate that the isothermally rolled sheet exhibits a coarse-grain microstructure with a large number of deformation twins. In contrast, the incremental temperature rolling process effectively decreases the grain size to 10.17 μm through the regulation of secondary phase. During isothermal rolling, an increase in the content of secondary phases (Mg_xZn_y) leads to larger particle sizes, which induces stress concentration, thereby contributing to premature material failure. Conversely, incremental temperature rolling facilitates interactions between secondary phases and high-density dislocation regions, acting as preferential nucleation sites during recrystallization, and thereby enhancing the plasticity of the material.