Hydrogen Embrittlement of CoCrFeMnNi High-Entropy Alloy Compared with 304 and IN718 Alloys

The hydrogen embrittlement (HE) behaviors of a CoCrFeMnNi high-entropy alloy (HEA), 304 stainless steel (304SS) and IN718 alloys were studied and compared via electrochemical hydrogen pre-charging, slow strain rate tensile tests, and fracture surface analysis. The results demonstrate that the HEA exhibited the greatest HE-resistance, followed by 304SS and then IN718 alloy, when the alloys were charged at 1.79 mA cm(-2) for 24 h and 48 h, and 179 mA cm(-2) for 2 h. Hydrogen-induced reduction in ductility was observed for 304SS and IN718 alloys, whereas the hydrogen-affected fracture strain of the HEA was dependent on the hydrogen charging time. The resistance to HE was improved at a short hydrogen charging time (24 h), but reduced at a long charging time (48 h). This is attributed to the competing mechanisms between hydrogen-enhanced twin formation and HEDE (hydrogen-enhanced decohesion).