Atomic-scale study of hydrogen-assisted crack propagation in FeNiCr medium entropy alloy

Hydrogen embrittlement leads to early failure of components used in hydrogen economy. Effects of the hydrogen concentration, loading rate and crystalline orientation on the incipient plasticity at the crack-tip in the FeNiCr medium-entropy alloy (MEA) are reported in present study by using atomistic simulations and the Peierls-type theory. The theoretical model predicts that the critical stress intensity factor (KIe) required for the dislocation emission increases with the increasing hydrogen concentration (cH), while simulation results show ignorable dependence between KIe and cH. The difference between theoretical prediction and numerical simulation lies on the fact that the general stacking fault energy is evaluated under quasi-static conditions, thus cannot capture the rapid dynamics of the hydrogen-dislocation interaction under high loading rates.