In-situ synthesis of SiC particles by the structural evolution of TiCx in Al–Si melt

Abstract

A facile method has been developed to in-situ synthesize SiC particles utilizing the structural instability and evolution of TiCx in Al–Si melt. It is considered that the synthesis of SiC particles occurs via the gradual reaction between TiCx and Si atoms, whilst Si content plays the crucial role in this approach. If the Si content in the melt is above 30%, TiCx directly reacts with Si and Al to form SiC, but the needle-like TiAlxSiy phase formed simultaneously will do harm to the mechanical properties of the composites. Thus, it is proposed to add B element in the melt to transform the TiAlxSiy into TiB2 particles. Therefore, the SiC and (SiC+TiB2) hybrid-particles reinforced Al–18Si composites were successfully prepared using the method. In the composites, the SiC particles have the size range from 2.5 to 7.5μm and a block-like morphology. Furthermore, the mechanical properties of base alloy, including the wear resistance and macro-hardness, have been obviously improved by the in-situ SiC particles. Besides, the relevant underlying mechanisms are also discussed.