State of a pressurized helium bubble in ironS. M. Hafez Haghighat, G. Lucas and R. Schäublin
Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse - CH 5232, Villigen PSI, Switzerland
received 6 November 2008; accepted in final form 24 February 2009; published March 2009
published online 6 April 2009
We study the state of a nanometric helium bubble in bcc-iron as a function of temperature and He content using atomistic calculations. It appears that up to moderate temperatures the Fe lattice can confine He to solid state, in good agreement with known solid-liquid transition diagram of pure He. However, He in the bubble forms an amorphous phase, while an fcc structure is expected at the same temperature and He density. In addition, the He bubble forms a polyhedron whose morphology depends on either the surface energy or the elastic-plastic properties of Fe at either low or high pressure, respectively. Indeed, at high He contents the bubble surface breaks down at the mechanical stability limit of the Fe crystal, leading to a pressure decrease in the bubble.
02.70.Ns - Molecular dynamics and particle methods.
61.82.Bg - Metals and alloys.
61.72.Qq - Microscopic defects (voids, inclusions, etc.).
© EPLA 2009