In-situ synthesis of nano SiC particles in Al-Si-C system at 750 °C

For SiCp/Al matrix composites, nano SiC particles (SiCp) show more obvious strengthening effect than micro ones. In general, nano SiCp are added into Al matrix by ex-situ method, during which interfacial and agglomerating problems often generate. In-situ method is considered an effective way to solve above problems, but the in-situ synthesis of nano SiCp hasn't been reported. In this research, nano SiCp were in-situ synthesized in Al-Si-C system via a liquid-solid reaction method at relative low temperature (750 degrees C). Microstructure observation shows that the obtained nano SiCp have 3C polytype and show hexagonal plate morphology, with average size under 100 nm. In order to lower its surface energy, nano SiCp tend to connect with each other and form a coherent interface with stacking faults. Further research reveals that nano SiCp are formed via a two-step reaction. Nano SiCp can be introduced into Al-Si alloy and elevate its strength both at room and high temperature. (C) 2021 The Authors. Published by Elsevier B.V.