Multi-scale simulations of the effects of irradiation-induced voids and helium bubbles on the mechanical properties of aluminium

Abstract

As a result of irradiation, pressurized helium bubbles are observed in large number densities in some metals, which produce mechanical property changes. This paper presents the results of a computational multi-scale study (dislocation dynamics, DD, and molecular dynamics simulations, MD) to quantify the effect of He bubbles on material hardening from the impediment to dislocation motion. The effects of voids were studied using MD, and the effects of He bubbles, with a mean size of 2.5 nm and number densities from 3 × 10²² m⁻³ to 6 × 10²² m⁻³, were investigated using DD over a range of internal He pressures ranging from 125 to 750 MPa. The MD simulations elucidated the dislocation pinning action of voids and bubbles. Also, within the range of parameters studied, the DD simulations showed a clear, but weak correlation between the number density of He bubbles, and the internal He pressure, on the flow stress of the metal.

Acknowledgements

The support of Lawrence Livermore National Laboratory (LLNL) to UNM is gratefully acknowledged. This work was performed, in part, under the auspices of the U.S. Department of Energy by LLNL (Subcontract No. B519473).