Effect of Sc microalloying on fabrication, microstructure and mechanical properties of SiCp/Al–Cu–Mg-Sc composites via powder metallurgy

Abstract

Overcoming the strength and ductility trade-off is a long-lasting research theme in aluminum matrix composites. Here, we present a strategy to promote strength-ductility synergy in aluminum matrix composites by utilizing the microalloying effect of Sc. 15 wt% SiCp/Al–Cu–Mg-Sc composites with varying Sc content were fabricated by high energy ball milling, hot pressure sintering and hot extrusion. With 0.2 wt% Sc addition, the SiCp/Al–Cu–Mg-Sc composite exhibits a yield strength of 600.6 MPa, an ultimate tensile strength of 681 MPa and a fracture elongation of 4.3%, achieving simultaneous enhancement in strength and ductility compared with the Sc-free counterpart. Particularly, the fracture elongation remarkably increased by 126% which originates from the reduction of stress concentration caused by the refinement of intergranular θ phase and the improvement of dislocation accumulation capability caused by the formation of intragranular θ' phase. Our work provides an accessible pathway consistent of high energy ball milling and microalloying of Sc to exploit aluminum matrix composites with advanced strength-ductility balance.