Helium bubble growth at BCC twist grain boundaries

Highlights: ► We model He bubbles in α-Fe at twist grain boundaries and bulk using MD. ► We study the pressures and volumes of the helium bubbles. ► The pressure of a bubble is lower at the twist boundary than in bulk. ► Interstitial loops are formed in all cases but are trapped at a twist boundary. ► The maximum density for the bubbles is found to be 1.7 He/VacFe. - Abstract: We study the growth of helium bubbles in α-Fe at low angle twist grain boundaries and in bulk using molecular dynamics and Metropolis Monte Carlo simulations. We describe the pressures and volumes of the helium bubbles and analyze the maximum pressure a bubble can sustain before emitting interstitial loops. We give a quantitative analysis of how these emitted loops behave differently in the bulk and at the grain boundary.