Grain coarsening behavior in a nanocrystalline copper subjected to sliding friction

•Nano-grains were obtained in Cu under sliding friction at the first 100 cycles.•An apparent grain coarsening behavior was observed during the continuing sliding.•Such a behavior is dominated by high stress, high strain and large sliding amplitude.

A grain coarsening behavior was reported in this work in nanocrystalline copper during sliding friction. The cross-sectional microstructure and micro-hardness of the pure copper subjected to sliding friction were investigated in detail. A nano-grained surface layer of copper was obtained after sliding against a WC-Co ball for the first 100 cycles. However, a pronounced grain coarsening was observed during the subsequent sliding cycles. Such a behavior is dominated by high stress, high strain as well as large amplitude adopted in sliding friction.