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 degrees C. However, the hardness of Cu-GN composite improves significantly above 450 degrees C and is nearly twice of that of Cu-GP composite at 600 degrees 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%. (C) 2016 Elsevier B.V. All rights reserved.