退火对 Mg-Mn-Ce 合金力学性能和导热性能的影响

Magnesium alloys, with ow density, high specific strength and good thermal conductivity, are key materials for the integrated application of lightweight and structural functions. However, the issue of insufficient plasticity and the coordinated improvement of strength and ductility remains a bottleneck for high thermal conductivity magnesium alloys. The effects of different annealing regimes on the microstructure, mechanical properties, and thermal conductivity of a rolled Mg-1.0Mn-2.0Ce (%, mass fraction) alloy are investigated. The rolled alloy contains mainly deformed grains with high dislocation density and strong basal texture (maximum intensity 7.7), which exhibits a yield strength of 224.2 MPa, an elongation of 0.8%, and a brittle fracture mode. After annealing at 400 ℃ for 5 min, rapid static recrystallization occurs, deformed grains disappear, and equiaxed grains are formed. The texture intensity decreases to 6.3, and the average KAM value decreases from 2.3° to 0.6°. The reduction of dislocations and substructures promotes the transformation of low-angle boundaries into high-angle boundaries, accelerating recrystallization and texture weakening. Mechanical properties are significantly improved: the yield strength reaches 228.1 MPa, the ultimate tensile strength exceeds 314.7 MPa, and the elongation increases to about 7.7%. The fracture mode changes to ductile fracture dominated by dimples. With increasing annealing temperature, dislocation, substructure, and boundary densities decrease, reducing electron scattering and improving thermal transport. The thermal conductivity increases from 132.4 W·m^{- 1}·K^{- 1} in the rolled state to 138.2 W·m^{- 1}·K^{- 1} after annealing. Short-time high-temperature annealing promotes recrystallization and texture weakening, achieving simultaneous enhancement of strength, ductility, and thermal conductivity, which provides a feasible approach for the design and processing optimization of high-strength and high-thermal-conductivity Mg-Mn-Ce alloys.