Ductile–brittle indentation fracture transitions in hard coatings

Abstract

The article has provided a novel way of finding the probability of fracture ( Pf) based on modifications of some established concepts. It has also discussed ductile to brittle as well as brittle to ductile transitions in the same coating/substrate system subject to differences in crystallisation, indenter sharpness, sliding modes and dislocation kinetics. The indentation positioning and nanocrystalline features cause ambiguity in the results and need meticulous analysis. As a result of increased dislocation movement, the crystalline portions toughened in contrast to the amorphous parts, which were more brittle. The Pf, which varies and reaches a maximum of 52% in the amorphous or near-amorphous area, was calculated using the Weibull distribution. Transitions between ductility and brittleness can be seen in sliding indentations. Evidence of adhesive failure, which required better coating component inspection because it happened significantly earlier, was shown. Finite-element modelling was used to analyse the stress and provide information on dislocation motions and the impact of indenter shape on fracture. The outcomes are advantageous for the production of devices based on nano/micro-electro-mechanical systems.