A high-entropy alloy for superior resistance to biogenic sulfuric acid corrosion and hydrogen embrittlement

The growing demand for metallic materials resistant to both environmental corrosion and hydrogen embrittlement under municipal wastewater conditions presents a significant challenge. Achieving superior resistance to both simultaneously is difficult due to microbial and acid-induced corrosion in wastewater alongside hydrogen embrittlement caused by the generation of free hydrogen during corrosion. These complex loading scenarios require materials capable of withstanding both forms of degradation. Here, we present a FeCoMnNiCu alloy, designed using the multiprincipal element concept, which forms a protective passive film and exhibits high resistance to both microbial and oxidative acid-induced corrosion. Furthermore, it shows exceptional resistance to hydrogen embrittlement with a hydrogen embrittlement index of approximately 4.01%. This is achievable because the alloy has a very low hydrogen diffusion coefficient and promotes hydrogen-induced twinning through the reduction of stacking fault energy. These properties establish the new alloy as a promising solution for components exposed to corrosive, hydrogen-rich municipal wastewater environments.