关键词: Mg-Zn-Ca-Mn镁合金, 微量Ce, 热挤压, 微观组织, 力学性能, 导热性

Abstract: Mg-2Zn-0.4Ca-0.2Mn(wt%) alloy with high thermal conductivity and elongation was prepared by near solidus temperature extrusion method, and the effect of trace Ce element on microstructure and properties was explored. The results indicate that the grain size in the extruded alloy exhibits a bimodal distribution, and the average grain size is significantly decreased compared with that of as-cast state. The addition of Ce not only transforms the second phase in the alloy from Ca₂Mg₆Zn₃ phase to (Mg, Zn)₁₁Ce phase, but also reduces the unrecrystallized area fraction from 5.4% to 1.6%, with an average grain size of 5.29 μm dropping to 3.68 μm, and the basal texture intensity of the alloy is significantly weakened. Due to the grain refinement strengthening effect and that of the second phase containing Ce, the yield strength of the alloy is significantly increased from 163.67 MPa to 237.44 MPa, while the elongation is reduced from 27.45% to 19.58%. The addition of Ce increases the volume fraction of the second phase in the microstructure, but it also reduces the solid solubility of Zn in the matrix, so the thermal conductivity of the alloy is not significantly reduced.

Key words: Mg-Zn-Ca-Mn magnesium alloy, trace Ce, hot extrusion, microstructure, mechanical properties, thermal conductivity