Friction-assisted pulse electrodeposition of high-performance ultrafine-grained Cu deposits

Ultrafine-grained (UFG) Cu deposits were prepared using pulse electrodeposition assisted by hard particle friction under strong cathodic polarisation in an additive-free bath. The effects of hard particle friction on the resulting electrochemical behaviour, microstructure, and mechanical properties of the deposits were studied. The results demonstrate that friction can effectively weaken the concentration polarisation and maintain the stability of the cathodic polarisation process. Periodic growth inhibition and the promotion of lateral growth owing to the applied friction lead to the formation of finer equiaxed grains (130 +/- 5 nm). The UFG Cu deposits produced using friction-assisted pulse electrodeposition had a preferential (111) orientation, compared to a (220) orientation in deposits produced using conventional pulse electrodeposition. The corresponding tensile strength was 630 +/- 15 MPa and the elongation to failure was 14.5 +/- 2.5%. The hardness and surface roughness were 183-204 HV and Ra 46 +/- 5 nm, respectively.