Issue
EPL
Volume 85, Number 6, March 2009
Article Number 60008
Number of page(s) 5
Section General
DOI http://dx.doi.org/10.1209/0295-5075/85/60008
Published online 06 April 2009
EPL, 85 (2009) 60008
DOI: 10.1209/0295-5075/85/60008

State of a pressurized helium bubble in iron

S. 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

masood.hafez@psi.ch

received 6 November 2008; accepted in final form 24 February 2009; published March 2009
published online 6 April 2009

Abstract
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.

PACS
02.70.Ns - Molecular dynamics and particle methods.
61.82.Bg - Metals and alloys.
61.72.Qq - Microscopic defects (voids, inclusions, etc.).

© EPLA 2009