Investigation on the structure and property of a gradient nanostructure CuCr25 with high hardness and high electrical conductivity

Surface mechanical attrition treatment (SMAT) was used to produce gradient nanostructure in CuCr25 alloy. A gradient structure up to 200 μm thick in its surface layer with grain size from nano-scale to micro-scale was obtained. The microstructural features of the surface layer produced by SMAT were systematically characterized. The average Cr and Cu grain size of the top surface layer was about 10 nm. The hardness of the SMATed surface layer after annealing treatment reached 475 HV which was three times higher than that of the original sample. The electrical conductivity of annealing sample was 46.5% IACS which was better than that of other nanocrystalline CuCr alloys. The SMAT treatment provides a new approach for preparation of CuCr alloy vacuum interrupters with high surface hardness and high electrical conductivity.