Effect of Silicon Addition and Thermal History on the Thermal Expansion Behavior of SiC/Al Composites
Two Al-Si alloys (Al-12Si and Al-20Si) and an industrial pure Al were reinforced with 70vol.% dual-sized SiC particles. The composites experienced annealing treatment, to investigate the effect of silicon addition and thermal history on the thermal expansion behavior of high SiC content aluminum matrix composites. The results showed that silicon additions led to a beneficial reduction in the coefficients of thermal expansion (CTEs) of the composites. In the temperature range between 20°C and 400°C, a continuous increase in CTEs with temperature was observed for SiCp/pure Al composite. However, the CTEs of SiCp/Al-12Si and SiCp/Al-20Si showed the maxima at 350°Cand 250°C respectively, then diminished at higher temperatures. This was related to the change of solid solubility of silicon in aluminum at elevated temperatures. The thermal expansion behavior of SiCp/Al composites was also influenced by thermal history. After annealing treatment, the CTEs were reduced when compared with those of as-cast composites. Annealing treatment reduced the original thermal residual stresses, and then altered thermal expansion behavior of the composites.
Yafang Han et al.
Q. Zhang et al., "Effect of Silicon Addition and Thermal History on the Thermal Expansion Behavior of SiC/Al Composites", Materials Science Forum, Vols. 546-549, pp. 649-652, 2007