Unveiling the inhibitory effect of hydrogen-decorated voids and dislocation loops on the glide of edge dislocation in tungsten

Tungsten (W), as the most promising candidate for plasma-facing materials, will experience significant irradiation hardening in nuclear fusion environment, which is originated from the formation of displacement damages, such as voids and dislocation loops. Hydrogen (H) can further exacerbate the hardening effect, but the underlying physical mechanisms remain unclear. Using molecular dynamics simulations, we investigate the impact of H aggregation within voids and ½ <111> dislocation loops on obstructing the glide of ½ <111> edge dislocations. On the one hand, the pinning effect of H-void complexes is closely related to the ratio of H to vacancy (H:Vac). When the H:Vac ratio is high, H atoms will overflow from the H-void complexes along the dislocation, enhancing the attractive interaction of complexes with dislocation and thereby causing a significant increase in the critical resolved shear stress (CRSS). On the other hand, the accumulation of H around dislocation loops can increase the CRSS by an order of magnitude. This is mainly because the binding of H to the dislocation loop hinders its movement along with the edge dislocation. Our findings advocate that the presence of interstitial impurities can dramatically modify the mechanical properties of materials underirradiation, and provide an important reference for the prediction of W performance and the development of advanced nuclear materials.