Microstructures and tensile properties of nano-sized SiCp/Al-Cu composites fabricated by semisolid stirring assisted with hot extrusion

Abstract

Al-Cu matrix composites containing nano-sized SiCp were successfully prepared by dispersing nano-sized SiCp/Al master alloy into the molten Al-Cu alloy with combined semi-solid stir casting and hot extrusion processes. Microstructures of nano-sized SiCp/Al-Cu composites and their tensile properties were investigated. Results show that the α-Al dendrites became finer and better formed and nano-sized SiCp was formed in the α-Al grains. With nano-sized SiCp adding to the Al-Cu matrix, the tensile strength of the described composites increased remarkably especially under the temperature of 453K, while their plasticity were still high. Nano-sized SiCp particles had been uniformly dispersed in the Al alloy, yielding composites with high strength at elevated temperatures. The strengthening mechanisms of nano-sized SiCp were also discussed. This will raise the probability of using Al matrix composites as lightweight materials for structural applications at elevated temperatures.