INFLUENCE OF THE GRAIN BOUNDARY σ-PHASE ON HYDROGEN EMBRITTLEMENT OF THE MULTICOMPONENT COCRFEMNNI ALLOY

This work established the effect of electrolytic hydrogen charging on the mechanical properties and mechanisms of fracture of the multicomponent Cantor alloy CoCrFeMnNi with different microstructures. It is shown that the formation of the grain-boundary σ-phase particles and, as a consequence, the creation of additional «particle/matrix» interfaces, helps to increase the resistance of the Cantor alloy to hydrogen embrittlement in terms of macromechanical behavior. The main factors that determine the thickness of brittle surface zones formed during hydrogen charging and subsequent uniaxial tension of hydrogen charged specimens have been identified, and the micromechanisms of fracture have been established. It is shown that the formation of the grain-boundary σ-phase particles increases the diffusion transport of hydrogen along the interfaces during plastic deformation, ensuring the formation of secondary cracks in the central part of the specimen, while the dislocation transport of hydrogen in the heterophase specimens is suppressed.