Breaking the trade-off between mechanical properties and thermal conductivity of magnesium alloys via regulating the partial Gibbs energy of alloying elements

Abstract

Magnesium (Mg) and its alloys are promising candidates for heat dissipation applications due to their low density and excellent thermal conductivity (TC). However, achieving both high strength and superior TC remains a challenge due to their inverse correlation. To address this, we employed phase diagram calculations to modulate the partial Gibbs energy of elements in the Mg–xZn–0.4E–0.4Zr alloy system (where x = 1, 2, 3, 4 wt. %, and E represents Sc, Sr, Gd, Sn, Ag, Si, Cu, Ca), based on the principle that reducing the concentration of solute elements in the matrix enhances TC. A series of ZXKCx000 alloys (x = 1, 2, 3, 4 wt. %) were synthesized, exhibiting both outstanding mechanical properties and enhanced TC. Notably, we identified a TC "stability window" driven by the consumption of solid solution atoms. Among these, the ZXKC3000 alloy demonstrates a TC comparable to that of the ZXKC2000 alloy while achieving superior mechanical properties, including an ultimate tensile strength of 257 MPa, an elongation of 19.1%, and a TC of 130.0 W·K^-1·m^-1. In addition, the partial Gibbs energy for other Mg alloys was calculated, further supporting the potential for simultaneous enhancement of mechanical properties and TC through this approach. This study provides valuable insights into the design of advanced Mg alloys with optimized TC and mechanical properties.