The effect of particle size and volume fraction of the reinforced phases on the linear thermal expansion in the Al–Si–SiCp system

Al–Si–SiCp composite systems were fabricated by spray-casting process and subsequently hot-extruded, and the effects of microstructural parameters, such as the volume fraction and particle size of the reinforced SiCp and Si phases on the linear coefficient of thermal expansion (CTE) were investigated. It revealed that the increase in the volume fraction of SiCp reinforcements lowers the linear CTE of the Al–Si–SiCp composite system, and the CTE of this system is proportional to the size of the crystallized silicon phase. The linear CTEs of the Al–Si–SiCp ternary systems were calculated for various sizes and volume fractions of the reinforced phases in the temperature range from 20 to 300 °C. It seems that the calculated CTEs agree well with the measured values. However, it showed that the calculated CTE values deviate slightly from previous reported ones at around 50 vol.% SiCp. Such deviations seem to be attributed to the combined effects of interfacial characteristics among phases in the system and other metallurgical factors such as shapes of reinforced phases, the probability of physical contact between phases, and porosities. Despite these deviations, it was verified that the linear CTEs of Al–Si–SiCp could be influenced considerably by the size of the reinforced phases.