Thermal expansion and dimensional stability of Al-Si matrix composite reinforced with high content SiC

An Al-Si (18-21wt.% Si) matrix composite reinforced with 73vol.% SiC particles was fabricated by squeeze casting technology. The thermal expansion behavior was studied from 20 to 400 °C. The coefficients of thermal expansion of SiCp/Al composite and unreinforced matrix exhibited maxima at 250 and 350 °C, respectively, then diminished at elevated temperatures. This was attributed to the increment of solid solubility of silicon in aluminum. The composite was also subjected to a thermal cycling test between 20 and 150 °C to evaluate its dimensional stability. A residual length change was observed at the end of cycling test. It was demonstrated that the thermal stresses played an important role in its dimensional change.