Effects of nano-SiCp content on microstructure and mechanical properties of SiCp/A356 composites assisted with ultrasonic treatment

Abstract nano-SiC p /A356 composites with different nano-SiC p contents were prepared by squeeze casting after ultrasonic treatment (UT). The effects of SiC p content on the microstructure and mechanical properties of the nanocomposites were investigated. The results show that with the addition of nano-SiC p , the microstructure of nanocomposites is obviously refined, the morphology of the α (Al) grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. The mechanical properties of 0.5%, 1% and 2% (mass fraction) SiC p /A356 nanocomposites are improved continuously with the increase of nano-SiC p content. Especially, when the SiC p content is 2%, the tensile strength, yield strength and elongation are 259 MPa, 144 MPa and 5.3%, which are increased by 19%, 69% and 15%, respectively, compared with those of the matrix alloy. The improvement of strength is attributed to mechanisms of Hall-Petch strengthening and Orowan strengthening.