Atomistic simulations of the elastic properties of helium bubble embedded aluminum

The helium bubble has significant consequence to the mechanical properties of irradiated materials. The influence of embedded helium bubble to the elastic properties of aluminum has been investigated by molecular dynamics (MD) simulations. The interaction between aluminum atoms and the interaction between helium atoms are described by an embedded-atom-method (EAM) many-body potential and a pair potential, respectively. Another pair potential, which is parameterized based on ab initio calculation, is used to describe the interaction between aluminum and helium atoms, and its validation under pressure up to 10 GPa is reasonable demonstrated by the electron density calculation. For the composite system consisting of 62,500 aluminum atoms and one helium bubble with various diameters, its elastic constants are calculated properly by stress–strain relation rather than by energy–strain relation. The results show that elastic constants c11, c12 and c44 decrease with increasing of the volume of the helium bubble, and remain almost invariable with the internal pressure of the helium bubble. The main reason is under high-pressure the helium is softer than aluminum, and the soft effect overwhelms the hard effect of internal pressure of helium bubble.