Intergranular corrosion behaviour of FeCoCrNi high-entropy alloy fabricated by selective laser melting

Abstract

Recently, high-entropy alloys (HEAs) show a wide application prospect in the marine field to achieve excellent corrosion resistance. In this paper, the intergranular corrosion (IGC) behaviour of FeCoCrNi high-entropy alloy fabricated by selective laser melting (SLM) at different laser powers (140, 170, 200, 230, and 260 W) was studied by microstructure analysis and double-loop electrochemical potentiokinetic reactivation. All specimens show high IGC resistance, and the degree of sensitisation of SLMed FeCoCrNi HEAs increased with the increase of laser power. Interestingly, no chromium carbides precipitation was found at the grain boundary, which indicates the intergranular corrosion mechanism of SLMed FeCoCrNi HEAs is totally different from that of most alloys caused by Cr depletion. It is found that the superior IGC resistance in SLMed FeCoCrNi HEAs produced by low laser power can be attributed to larger grain size, a higher fraction of [Formula: see text][Formula: see text] ([Formula: see text] 3), and low-[Formula: see text] coincidence site lattice boundaries. This work provides a strong insight into the application of additive-manufactured HEAs in harsh corrosion environments.