Influence of crystalline defects on nitrogen implantation in copper for surface hardening

The design of electrical contacts that combine a high electrical conductivity and excellent wear resistance requires the optimization of surface processing. Surface hardening of copper was achieved by nitrogen implantation and the underlying mechanisms were investigated by electron microscopy. Pure copper and a CuSn alloy were implanted with nitrogen in the recrystallized state and after severe plastic deformation. The larger lattice parameter of CuSn does not promote the implantation of N but the large density of crystalline defects in the asdeformed material gives rise a much thicker implanted layer up to 120 +/- 20 nm. In all cases, the strong hardening results from a high density of nanoscaled Cu3N particles (1.2 +/- 0.4 1023 m(-)3). Deformation twins seem to promote both the diffusion and the nucleation of Cu3N.

Automated summary

The design of electrical contacts with both high electrical conductivity and excellent wear resistance can be achieved by surface hardening through nitrogen implantation. Electron microscopy was used to investigate the underlying mechanisms. The study found that the larger lattice parameter of CuSn does not promote nitrogen implantation, but the high density of crystalline defects in the severely deformed material leads to a thicker implanted layer. The strong hardening is attributed to the high density of nanoscaled Cu3N particles.