Comparison of microstructures and tensile properties of pulse electrodeposited Ni on polycrystalline and amorphous substrates

Abstract

Ultrafine grained nickel (UFG Ni) and microcrystalline nickel (MC Ni) were fabricated on two types of substrates, i.e. the amorphous (Ni–P) and polycrystalline (stainless steel) substrates by pulse electrodeposition without additives. This study demonstrates that when inhibiting the epitaxial growth by first depositing a thin amorphous layer on the polycrystalline substrates, the grain size of the subsequent Ni deposit decreases dramatically from microscale to the UFG regime, which depends on the deposition conditions. Compared with MC Ni, which has an ultimate tensile strength σ_UTS of 397 MPa and an elongation to failure ε_TEF of 11·98, UFG Ni with an average grain size of 120·72 nm exhibits an enhanced σ_UTS of 807 MPa and a comparable ε_TEF of 10·44. The electrodeposited method used in this study provides an effective and low cost way to produce UFG materials with both high strength and ductility, which can meet the demands for practical application as structural materials.