Ultrahigh strength ultrapure nanostructured nickel metal prepared via ultrafine anode scanning electrodeposition

Abstract

The existed synthesis methods for producing high microhardness nanostructured metal materials (NMMs) are usually at the cost of reducing the tensile strength and introducing heterogeneous elements, thus making forming ultrahigh strength ultrapure NMMs significantly challengeable. We unprecedentedly produced ultrapure (99.9997%) nickel deposits simultaneously with an ultrahigh strength and mirror-like surfaces as well as an appreciably high ductility by using our proposed ultrafine anode scanning electrodeposition (UAS-ECD). Distinctively, the UAS-ECD is a speed-dependent localized scanning electrodeposition rather than a commonly-used current-dependent electrodeposition. Therefore, the UAS-ECD can create NMMs at extremely high local current densities and with no additives. This makes it achievable to generate ultrahigh strength ultrapure NMMs with microhardness of 656 HV and tensile strength of 664 MPa (fracture elongation, 8.5%), which are respectively 29% and 30% higher than those reported in the literature. Further surprisingly, the samples’ tensile strength has only an approximately 1% reduction after being annealed. This is attributed to minimum impurities introduction and evenly distributed ultrafine grains formed. In addition, UAS-ECD is able to produce grain-varying deposits just by adjusting the anode’s scanning speed, conveniently achieving 65 wt%-95 wt% nano-& micro-sized grains composite NMMs. This work provides a novel strategy for synthesizing ultrahigh strength ultrapure NMMs.

Keywords

• Ultrahigh strength
• Ultrahigh purity
• Nanocrystalline
• Ultrafine anode scanning electrodeposition
• Electrodeposition