Interactions between hydrogen bubbles and prismatic interstitial dislocation loops in BCC iron

Abstract

The interaction between the interstitial dislocation loop and the hydrogen bubble has been investigated using the molecular dynamics (MD) method, to understand the behavior of dislocation loops in iron-based alloys for the future nuclear systems in which high concentration of hydrogen is created in structural materials. Based on the simulation results, the pinning effect of hydrogen bubble on prismatic interstitial dislocation loop is proposed in bcc iron. The dislocation loop can be attracted to a hydrogen bubble and locked by it when the dislocation loop is in contacts with the bubble. The dislocation loop gliding is also impeded through the elastic interaction with a hydrogen bubble, but without directly colliding with it. When the attractive interaction between a hydrogen bubble and an interstitial dislocation loop is strong enough, the hydrogen bubble can capture the dislocation loop directly and they annihilate with each other. The switching of these interaction mechanisms depends on sizes of the dislocation loop and the hydrogen bubble, the anglen and the distance between the loop and the bubble, and the surface density of hydrogen atoms in the bubble. All these results provide new insight on hydrogen effect in irradiated iron-based materials.