Enhancement of impact resistance of Fe-based amorphous coating by Al2O3 dispersion

The load-bearing applications of Fe based amorphous coatings are limited due to their poor impact resistance. Here, we have designed an amorphous composite coating reinforced with 20wt% Al2O3 particles that is tougher and more impact resistant than the monolithic amorphous coating. Impact resistance of the coatings was systematically studied by drop-weight impact tests and finite element modelling (FEM). It was found that the hard Al2O3 particles in the composite coatings could effectively hinder crack propagation via the formation of micro-cracks inside the Al2O3 particles, which absorbs the impact energy. FEM indicates that the Al2O3 dispersion acts as the main loading-bearing phase and alleviates the stress concentration in the composite coating, thus suppresses crack initiation and propagation. Furthermore, electrochemical polarization test shows that composite coating remains good corrosion resistance in a 3.5% NaCl solution after impact. [Display omitted] •20% Al2O3 particle addition remarkably improves the impact resistance of amorphous coating.•Al2O3 particles absorb impact energy by crack deflection and micro-crack mechanisms.•Al2O3 particles alleviate the stress concentration upon impacting revealed by FEM.•The composite coating is more corrosion resistant than the monolithic coating after impact.