Effect of Si addition to Al–8Mg alloy on the microstructure and thermo-physical properties of SiCp/Al composites prepared by pressureless infiltration

Fifty-five volume percentage of SiCp/Al composites were prepared by pressureless infiltration to investigate the effect of Si addition to Al–8Mg alloy from 0 wt% to 18 wt% on the interfacial reaction between Al and SiC and the thermo-physical properties of the prepared composites. TEM and X-ray analysis showed that the degree of interfacial reaction decreased as the Si content increased, and that it ceased at 1273 K when the Si addition to the aluminum was greater than 12 wt%. The Si addition to Al–8Mg alloy reduced the CTE of the composites and increased their thermal conductivity (TC), but Si beyond 12 wt% led to the reduction of TC, though the CTE was lower. This is attributable to the combined action of the Si on the wettability, interfacial reaction and the TC and CTE of the matrix itself.