Synergistic enhancement of thermal conductivity and mechanical properties in cast Mg-Zn-Zr-Sr alloys via grain refinement and solute redistribution

To address the trade-off between thermal conductivity and mechanical properties in magnesium (Mg) alloys and broaden their application in advanced thermal management, a series of high-strength, high-thermal-conductivity cast Mg-xZn-0.1Zr-0.05Sr alloys (x = 1, 2, 3, 4 wt%) were successfully designed and fabricated. The results show that grain size decreases with increasing Zn content. Reducing solute atom concentration in the α-Mg matrix and promoting their precipitation as nanoscale, dispersed, rod-like MgZn₂ phases effectively mitigates the negative impact of alloying on thermal conductivity. Both mechanical strength and thermal conductivity were significantly improved after artificial aging (T6) heat treatment. Among the alloys, Mg-4Zn-0.1Zr-0.05 Sr demonstrated the best overall performance, with an ultimate tensile strength of 259 MPa, elongation of 18.1 %, and thermal conductivity of 133 W·m⁻¹·K⁻¹. This study offers valuable guidance for designing Mg alloys with well-balanced thermal and mechanical properties through grain refinement and solute redistribution, supporting the development of structural-functional-integrated Mg materials. © 2025 Elsevier B.V.