Exploring the size effects of Al₄C₃ on the mechanical properties and thermal behaviors of Al based composites reinforced by SiC and carbon nanotubes

In this work, the effects of aluminum carbide (Al₄C₃) on the mechanical properties and thermal behaviors of Al based composites reinforced by SiC and carbon nanotubes (CNTs) were investigated. The formation of Al₄C₃ was precisely controlled in the temperature range from 530 °C to 630 °C (80%–95% of the Al melting point) during the post heat treatment. Microscopy observations revealed that Al₄C₃ rods are originated from CNTs instead of SiC particles. Quantity and size of Al₄C₃ are highly dependent on the heat treatment temperature. It was found that the mechanical properties of the Al based composites were significantly affected by the size of Al₄C₃. Moreover, the formation of Al₄C₃ helps to decrease the coefficient of thermal expansion (CTE) of the composites due to the consumption of Al and the enhanced interfacial bonding. This study provides a potential approach for ameliorating the mechanical and thermal performances of CNTs reinforced metal matrix composites.