Dynamic deformation mechanism in submicro-laminated copper with interlamellar graphene multilayers

The plastic deformation of metals is usually sensitive to loading rates, and such rate-dependent behaviors are influenced by various factors, among which inclusions especially nanoinclusions such as graphene and carbon nanotubes were found to have dramatic influence on the deformation mechanisms of metallic materials. However, relative studies are basically focused in quasi-static regimes. Here, the full spectrum of deformation behaviors of graphene/copper (Gr/Cu) submicro-laminated composites at wide-range strain rates (from 10−4 /s to ≥108 /s) and various temperatures (room temperature and -70 °C) are provided, and relevant mechanisms, especially when deformed at high strain rates and low temperatures, are studied elaborately. Unlike conventional copper materials whose strain rate sensitivity drops dramatically (∼50%) with decreasing temperature, Gr/Cu submicro-laminates has an enhanced strain rate sensitivity that decreases limitedly (∼10%) with temperature. Microstructural analysis revealed that a graphene-assisted deformation mechanism dominated the dynamic compression of Gr/Cu composites, where graphene inclusions act as lubricants that enhanced the deformation ability of the submicro-laminates. Further analysis on copper matrix revealed that dislocation dominated deformation switch to twinning dominated deformation from high to extreme strain rates loading, and extreme loading conditions as well as graphene inclusions are prerequisites for high-density deformation twins in Gr/Cu submicro-laminates.