Strengthening‐toughening of graphene nanoplates and in situ ZrB2 nanoparticles reinforced AA6111 matrix composites with discontinuous layered structures

Abstract

Simultaneously achieving high strength and ductility is a critical issue for graphene nanoplates (GNPs) reinforced aluminum matrix composites. Layered structures and in situ nanoparticles were applied to achieve the strengthening and toughening of GNPs reinforced aluminum matrix composites from the structure and composition design, respectively. Therefore, the discontinuous layered AA6111 matrix composites synergistically reinforced with GNPs and in situ ZrB2 nanoparticles were prepared by the composite melt preparation method and hot rolling. The discontinuous layered structure features of graphene, particles, and matrix were investigated. The interfaces between reinforcements and the matrix were further characterized by high-resolution transmission electron microscopy. It was found that the improved load transfer efficiency of GNPs was mainly attributed to the formation of a high-strength amorphous alumina interface between GNPs and the aluminum, as well as the pinning effect of the Al2Cu particles on GNPs' surface. By analyzing characteristics of the dislocation configuration, GNPs and nanoparticles boosted the dislocation storage capacity of the composite, while the particles dispersed the stress concentration at the edge tip of GNPs, thereby improved the composite's ductility. The composite achieved a 50% (349 MPa) increase in yield strength with only a 30% compromise on ductility (13.8%), leading to a notable improvement in toughness. The research revealed an efficient way for manufacturing high strength-ductility metal matrix composites with discontinuous layered structures via well-bonded interfaces employing GNPs and nanoparticles.