The effect of thermal mismatch on the thermal conductance of Al/SiC and Cu/diamond composites

Abstract

Thermal mismatch at the interface is inevitable in the manufacturing process of metal matrix composites. The relationship between strain and thermal conductivity of metal is obtained. The plastic strain region caused by thermal mismatch and its effect on thermal conductance of Al/SiC and Cu/diamond are acquired and discussed using the finite element method. It is found that the average strain is independent of particle size and proportional to the ratio of particle radius to distance. The strain will affect the thermal conductivity of composites in two ways. One is to decrease the effective thermal conductivity of matrix, which is more significant for the Al/SiC system than the Cu/diamond system, but it has a relatively small impact on the thermal conductivity of composites. The other is to reduce the interfacial thermal conductance (ITC) by weakening interfacial bonding and scattering phonon transport, making the effective thermal conductivity of reinforcement and thermal conductivity of composites decrease, which has a bigger impact on composites with high thermal conductance reinforcements. The results also show that there is an increase of thermal conductivity of composites with ITC in a specific region determined by particle size, and the composite reinforced with large particles has a higher thermal conductivity at low ITC because of the low density of interface. Our work is important for understanding the effect of thermal mismatch on thermal conductance of metal matrix composites and provides a way to bridge the relationship between mechanical behavior and physical properties.