Hydrogen-induced slip localization around a quasi-brittle fatigue crack observed by high-voltage electron microscopy

The effect of hydrogen on cyclic slip behavior around a fatigue crack tip in a bulk Fe–Si alloy is successfully observed by high-voltage electron microscopy. The observation explicitly reveals the following points: (i) hydrogen reduces the amount of cyclic slip whereas it promotes crack growth rate; and (ii) hydrogen induces a quasi-brittle crack growth that accompanies localized slip in the crack periphery.