Nano- and micro-mechanical properties and corrosion performance of a HVOF sprayed AlCoCrFeNi high-entropy alloy coating

In this work, a gas atomized feedstock was used to fabricate an AlCoCrFeNi HEA coating using the high-velocity oxygen fuel (HVOF) process. The coating's resistance to room temperature surface degradation was evaluated using dry sliding wear and seawater corrosion testing. The coating retained the feedstock phase structure with negligible in-flight oxidation and was composed of a majority BCC phase with a minor B2 phase, resulting in a high micro-and nano-hardness of similar to 7 GPa. These observed phase compositions were consistent with thermodynamically calculated phase predictions using a CALPHAD model. Microstructure-mechanical property mapping revealed uniform microstructural characteristics. However, the multiscale wear resistance of the coating was critically affected by the presence of the hard BCC/B2 phase composition, which led to severe brittleness. Combinatorial assessment of the worn surface, wear debris and counter body indicated that wear was dictated by a combination of abrasive, surface fatigue, tribo-oxidation and adhesive wear. In addition, the coating exhibited superior general corrosion resistance compared with conventional SS316L, but the selective dissolution of the B2 phase preceded poor localized corrosion re-sistance, ultimately leading to pitting corrosion.(c) 2022 Published by Elsevier B.V.

Automated summary

In this study, an AlCoCrFeNi HEA coating was fabricated using gas atomized feedstock and the HVOF process. The coating exhibited resistance to surface degradation at room temperature and had high micro-and nano-hardness. However, the presence of the hard BCC/B2 phase composition led to severe brittleness and affected the wear resistance of the coating. The coating also showed superior general corrosion resistance but was susceptible to pitting corrosion due to the selective dissolution of the B2 phase.