Back stress dynamic balancing strategy enabled strength-ductility synergy in heterostructured Al-SiC composites

Strength-ductility trade-off dilemma remains a significant obstacle to high-strength composites due to the undesirable dislocation storability. Herein, an ingenious nano-micro SiC-reinforced Al matrix composite (AMC) with heterogeneous grain structures of coarse and fine grains was designed via a novel deformation-driven metallurgy method. The accumulated geometrically necessary dislocations and the intragranularly dispersed SiC particles were tailored based on the principle of back stress amelioration, which was a key point to maintain the dynamic balance with the applied stress toward strength-ductility synergy. The ultimate tensile strength and uniform elongation of the designed SiC5(np-5 mu p)/Al composite reached 324 MPa and 12.9%, respectively, and the strength was 181% as high as that of the SiC10(mu p)/Al with only 3% ductility loss. As such, a new strategy was provided herein to promote strength-ductility synergy via the further modified back stress.