Microstructural Characterization and Optimization of CoCrCuFeMnNi High Entropy Alloy to be in Contact with Hydrogen

This study aims to develop a High Entropy Alloy (HEA) with reduced susceptibility to Hydrogen embrittlement (HE) and improved resistance to oxidation, potentially surpassing existing materials in hydrogen-rich environments. Microstructural analysis revealed a dendritic structure where two FCC phases have been formed: a dendritic zone with the designed composition and a Cu-rich interdendritic structure with reduced Mn content. The second phase has been eliminated with the application of heat treatment but Cr-rich segregation in grain boundary appeared during a prolongated exposure at 1100℃, which could correspond to σ phase. Segregation of σ phase might be eliminated with an optimization of the composition or heat treatment conditions, achieving a single-phase solid solution.