Phase transformation mechanism of Al4C3 by the diffusion of Si and a novel method for in situ synthesis of SiC particles in Al melt

Abstract

The in situ synthesis of SiC particles in Al melt is reasonably difficult since carbon has quite poor wettability and extremely tiny solubility in the melt. A liquid–solid reaction couple was designed in this paper. Si atoms diffuse into Al4C3 phase, resulting in the gradual transformation Al4C3→Al4SiC4→SiC. The concentration of Si is a key factor affecting the transformation procedure, and SiC can only be synthesized at a relatively high Si content. By applying the mechanism into casting method, SiCp reinforced Al18Si alloys were successfully prepared, and the hardness, wear resistance and tensile properties were improved. The method provides a novel suggestion for the preparation of in situ SiC particles reinforced Al-Si matrix composites.