Significantly improving the performances of thermal conductivity and thermal expansion in aluminum matrix composites through a multiphase design strategy

Developing metal matrix composites with low thermal expansion yet high thermal conductivity (λ) has been an ongoing effort in electronic packaging materials due to the growing demand for high-power applications. However, progress has been hindered by the insufficient thermal expansion suppression of conventional low thermal expansion reinforcements or the low λ of negative thermal expansion reinforcements. In this study, this challenge is overcome via a multiphase design strategy using ZrW2O8 and SiC to co-reinforce the aluminum matrix composites. This approach simultaneously combines the advantages of the ZrW2O8 for controlling the coefficient of thermal expansion (CTE) and SiC for improving λ. A controlled CTE-λ balance (6.22-9.7 × 10-6 K-1, 63.1-131.1 W/mK) can be obtained by varying the volume ratio of ZrW2O8 to SiC. The CTE of this composite is significantly lower than that of the 50 vol% SiC/Al composite, while its CTE is approximately equal to that of the 45 vol% ZrW2O8/Al composite but with a twofold increase in λ. The good thermal performance of this composite can be attributed to the strong interfacial interactions of SiC and the tailored variation in CTE. Furthermore, simulation and experimental results revealed that the residual stress can be effectively relieved through this strategy. This work presents a straightforward structural design and an effective pathway to manufacture composites with excellent integrated properties.