Improved high temperature strength of copper-graphene composite material

The strength of polycrystalline materials at high temperatures is limited due to their poor resistance to grain boundary motion. A strategy to anchor the grain boundary of copper in 2-dimensional curvature by graphene was proposed and the copper-graphene composite was therefore fabricated. It was found that the hardness of Cu-0.5 wt% graphene (GN) composite is almost same with that of Cu-0.5 wt% graphite (GP) composite between room temperature and 450 °C. However, the hardness of Cu-GN composite improves significantly above 450 °C and is nearly twice of that of Cu-GP composite at 600 °C, indicating the hindrance effect of graphene on the atom diffusion across grain boundary at high temperatures. On the other hand, the thermal expansion coefficient is lower for Cu-GN composite compared with that of Cu-GP composite, and the electrical conductivity of the Cu-0.5 wt% GN composite remains 95.9 IACS%.