Hydrogen embrittlement of a precipitation-strengthened high-entropy alloy

The present study explores the hydrogen embrittlement characteristics, cracking mechanism, and the impact of hydrogen on the deformation microstructure of (FeCoNi)86Al7Ti7 high-entropy alloy (HEA). The cracking induced by hydrogen primarily manifests as intergranular cracking, with the interaction between the L21 phase and dislocation slip at grain boundaries promoting the hydrogen-enhanced decohesion mechanism. The distinct work hardening stage is observed during the tensile testing of hydrogen-charged samples. This additional work hardening is attributed to the early formation of microband structures, which correlates with stacking fault energies and directional dislocation substructure. However, the propagation of crack significantly diminishes the ductility.