Properties of Helium bubbles in Fe and FeCr alloys

Abstract We investigate three aspects of He that are relevant for its behavior in FeCr alloys. (i) the EOS of pure He, as an auxiliary element to relate pressure and density inside a bubble; (ii) He bubbles in FeCr alloys, to explore the influence of Cr as solute and at α′ precipitates on the He precipitation behavior; (iii) the growth mechanism of a He bubble in Fe and Fe 15 at% Cr under the particular conditions of a He-rich and vacancy poor environment. This last case represents an extreme situation that reveals the maximum pressures that can be achieved by a bubble before the matrix yields. We observe the emission of interstitial dislocation loops as the mechanisms by which the bubble creates room to host the He atoms. We use molecular dynamics and Monte Carlo computer simulations based on a new ternary FeCr–He empirical potential, which is an extension of our previous composition-dependent model for FeCr (A. Caro et al., Phys. Rev. Lett. 95 (2005) 075702).