Strength-ductility balance strategy in SiC reinforced aluminum matrix composites via deformation-driven metallurgy

Abstract The strategy of the strength-ductility balance of aluminum matrix composites (AMCs) reinforced with nano- and micro-SiC particles via deformation-driven metallurgy was designed. The grain refinement of SiCnp/AMCs was promoted with the nano-SiC particles intragranularly-dispersed, and the stability of the ultra-fine-grains was improved due to the Zener pinning mechanism. The ultimate tensile strength of the SiCnp/AMCs was increased significantly, reaching 435 MPa and kept the ductility at 9%. A typical multimodal grain microstructure of SiCμp/AMCs was obtained with micro-sized grains and ultrafine grains as the localized grain refinement was promoted by the particle stimulated nucleation mechanism and was intensified by the broken micro-SiC particles. The ductility of the SiCμp/AMCs was kept well, reaching 18%, and kept the ultimate tensile strength at 200 MPa. Therefore, the microstructure of SiC/AMCs could be designed to balance the strength and ductility via optimizing the SiC particles according to the needs of practical applications: matrix strength could be increased by selecting a certain amount of nano-SiC particles; while an excellent ductility could be obtained by adding the appropriate amount of micro-SiC particles.