Micro-Compression Test of Nanocrystalline Nickel Deposited by Supercritical Carbon Dioxide Emulsion

Abstract

This paper reports experimental results of compression test on non-tapered rectangular shaped micro-pillar fabricated by focused ion beam techniques. The pillar is composed of electrodeposited nickel in additive-free Watts bath emulsified with supercritical carbon dioxide. We found that the electroplated film does not contain any defects or pores and has grain size of 8 nm. Maximum compression flow stress exceeds 3.5 GPa without any failure up to 9 % of permanent strain. This is 10 times higher than the strength of the single crystal nickel counterparts fabricated using the same focused ion beam techniques loaded along . This is because of the enhanced mechanical properties by grain boundary strengthening in nanocrystalline nickel and defect-free nickel film. Carbon impurity observed in the nickel film fabricated by electroplating with supercritical carbon dioxide emulsion enhances cohesion of the grain boundary and inhibits grain boundary sliding, which is the predominant deformation mechanisms in this grain size regime.