The influence of grain size on hydrogen embrittlement of a multicomponent (FeCrNiMnCo)99N1 alloy

The problem of hydrogen embrittlement remains relevant in many areas, so the FeCrNiMnCo alloy (Cantor alloy) generates increased interest among researchers as one of the materials least exposed to the negative effect of hydrogen. Nevertheless, the issue of the influence of microstructure parameters on hydrogen embrittlement of the Cantor alloy and multicomponent alloys of the FeCrNiMnCo system in general remains understudied. This work studies the influence of grain size on the susceptibility of a nitrogen-doped high-entropy Cantor alloy to hydrogen embrittlement. For this purpose, states with different grain sizes (43±21, 120±57, and 221±97μm) were formed in the (FeCrNiMnCo)99N1 alloy, using thermomechanical treatments. It is experimentally found that grain refinement leads to an increase in the strength properties of the alloy under study and promotes an increase in the resistance to the hydrogen embrittlement: in samples with the smallest grain size, the hydrogen-induced decrease in ductility is less than in samples with the largest one. A decrease in grain size causes as well a decrease in the length of the brittle zone detected on the fracture surfaces of samples after tension. This is caused by a decrease in hydrogen diffusion during the hydrogen-charging process and a decrease in the transport of hydrogen atoms with mobile dislocations during plastic deformation due to a decrease in grain size.