Elevating strength–ductility synergy in aluminum matrix composites by multiscale and dual-structured reinforcing particulates

To elevate strength–ductility synergy in aluminum matrix composites, we propose a strategy of forming multiscale and dual-structured (M&D) reinforcing particulates, which are composed of nano-/submicro-particulates with monolithic structure (< 2 μm) and micro-particulates with core–shell (CS) structure (> 2 μm), and explore the effects of particulate fraction on microstructure and tensile properties. The results show that an increase in M&D particulate fraction decreases the grain size of Al matrix due to impeding of particulates against disappearance of grain boundary, and the tensile strengths increase significantly while the elongation first increases and then decreases. Comparatively, the synthesized M&D particulates in this work exhibit a much better toughening effect than CS particulates or traditional monolithic ones. Corresponding strengthening and toughening mechanisms are discussed from the perspective of strength contribution calculation, post-deformed transmission and scanning electron microscopy observations. This work would provide references for conquering the low ductility of metal matrix composites and promotes their widespread application in industry.