Orbital-free density functional theory study of the energetics of vacancy clustering and prismatic dislocation loop nucleation in aluminium

Abstract

In the present work, we conduct large-scale orbital-free density functional theory calculations to study the energetics of vacancy clustering in aluminium from electronic structure calculations by accurately accounting for both the electronic structure and long-ranged elastic fields. Our results show positive binding energies for a range of vacancy clusters considered. However, the binding energies for the various quad-vacancy clusters considered in this study are vastly different, and only some of these clusters are found to be stable with respect to dissociation into divacancies. This suggests that, while vacancy clustering is an energetically feasible mechanism, this happens preferentially through the formation of certain vacancy clusters. Among the vacancy clusters considered in this study, the 19 vacancy hexagonal cluster lying in plane has a very large binding energy with the relaxed atomic structure representative of a prismatic dislocation loop. This suggests that vacancy prismatic loops as small as those formed from 19 vacancies are stable, thus providing insights into the nucleation sizes of these defects in aluminium.

Keywords:

• Crystal defects
• defect structures
• density-functional methods
• vacancies
• dislocations

Acknowledgements

We thank Dr Amuthan Arunkumar Ramabathiran for assistance in the visualisation of the atomic structure of the prismatic loop.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

We are grateful to the support of National Science Foundation [grant number CMMI0927478] under the auspices of which this work was conducted. V.G. also gratefully acknowledges the hospitality of the Division of Engineering and Applied Sciences at the California Institute of Technology while preparing this manuscript. We also acknowledge the Advanced Research Computing at University of Michigan for providing the computing resources through the Flux computing platform.