Achieving near-net-forming of in-situ fabricated SiCp/2024Al composites with high performance by friction stir channeling assisted stationary shoulder friction stir processing

This study developed a novel friction stir channeling assisted stationary shoulder friction stir processing (CaSSFSP) approach to minimize surface thinning and the ejection of reinforcement particles commonly encountered in conventional FSP, and successfully applied it to fabricate 10 vol% SiCp/2024Al composites. The influence of processing passes on the uniformity of SiC particles distribution was investigated. The microstructural characteristics, mechanical and tribological properties of the composites were systematically analyzed and evaluated. The results demonstrated the excellent near-net-forming capability of the CaSSFSP approach. With an increase in the number of processing passes from two to four, the formation of onion rings was significantly suppressed, leading to a remarkable improvement in the mechanical properties of the composites. After four-pass CaSSFSP processing, the composites achieved an elastic modulus of 92.7 GPa, a 23.9 % improvement over the matrix. Following T6 heat treatment, the yield strength of the composites reached 364.1 MPa, 16.7 % higher than that of the base metal. The wear rate was reduced by 35.2 % compared with the base metal. The enhanced mechanical and tribological properties are mainly attributed to the uniform distribution of SiC particles and their strong interfacial bonding with the aluminum matrix. Theoretical analysis further indicates that grain boundary strengthening and precipitation strengthening are the dominant strengthening mechanisms in the SiCp/2024Al composites.