The critical challenge of chip thermal dissipation fundamentally constrains both power consumption and operational longevity, underscoring the imperative demand for advanced packaging materials exhibiting superior thermal conductivity coupled with ultralow thermal expansion. Magnesium-based packaging systems demonstrate considerable promise in this strategic domain; however, current research efforts remain notably sparse, particularly regarding SiC particulate (SiC_P)-reinforced magnesium matrix composites. In this investigation, we prepared SiC_P-reinforced magnesium matrix composites through optimized stir casting methodology and systematically investigated their thermophysical characteristics. Remarkably, the composite incorporating merely 25 vol.% SiC_P exhibited exceptional thermal performance metrics: a thermal conductivity of 178.5 W/(m·K) and a coefficient of thermal expansion as low as 16.8 × 10⁻⁶ K⁻¹. Furthermore, molecular dynamics simulations were employed to elucidate thermal transport mechanisms at Mg/SiC interfaces, revealing that chromium interlayer implementation substantially enhances interfacial thermal conductance compared to direct bonding configurations. This comprehensive study not only validates the efficacy of SiC_P reinforcement in optimizing magnesium matrix composites’ thermophysical properties but also establishes Mg/SiC_P composites as a cost-competitive solution for next-generation thermal management applications.

The primary cause of the decrease in thermal conductivity of conventional thermal conductive magnesium alloys is electron scattering brought on by solute atoms. However, the impact of phase interface on thermal conductivity of magnesium alloys is usually disregarded. This study has developed a Mg-Si-Zn-Cu alloy with high thermal conductivity that is distinguished by having a very low solute atom content and a significant number of phase interfaces. The thermal conductivity of the Mg-1.38Si-0.5Zn-0.5Cu alloy raises from its untreated value of 133.2 W/(m·K) to 142.2 W/(m·K), which is 91% of the thermal conductivity of pure Mg. This is accomplished by subjecting the alloy to both 0.8wt% Ce modification and T6 heat treatment. The morphology of eutectic Mg₂Si phase is changed by Ce modification and heat treatment, and as a result, the scattering of electrons at the Mg₂Si/Mg interface is reduced, resulting in increase of the alloy’s thermal conductivity.