Effect of Interfacial Reaction on the Thermal Conductivity of Al–SiC Composites with SiC Dispersions

Abstract

The effect of interfacial reactions between Al and SiC on the thermal conductivity of SiC‐particle‐dispersed Al‐matrix composites was investigated by X‐ray diffraction and transmission electron microscopy (TEM), and the thermal barrier conductance (hc) of the interface in the Al–SiC composites was quantified using a rule of mixture regarding thermal conductivity. Al–SiC composites with a composition of Al (pure Al or Al–11 vol% Si alloy)–66.3 vol% SiC and a variety of SiC particle sizes were used as specimens. The addition of Si to an Al matrix increased the thermal barrier conductance although it decreased overall thermal conductivity. X‐ray diffraction showed the formation of Al4C3 and Si as byproducts in addition to Al and SiC in some specimens. TEM observation indicated that whiskerlike products, possibly Al4C3, were formed at the interface between the SiC particles and the Al matrix. The thermal barrier conductance and the thermal conductivity of the Al–SiC composites decreased with increasing Al4C3 content. The role of Si addition to an Al matrix was concluded to be restraining an excessive progress of the interfacial reaction between Al and SiC.