Molecular dynamics simulations of irradiation defects in graphite: Single crystal mechanical and thermal properties

T Trevethan and MI Heggie, COMPUTATIONAL MATERIALS SCIENCE, 113, 60-65 (2016).

DOI: 10.1016/j.commatsci.2015.11.012

Molecular dynamics simulations of single crystal graphite have been performed, incorporating point and extended defect structures formed as a result of thermally annealed radiation damage. These AIREBO potential calculations have simulated the changes to crystal dimensions, elastic moduli and thermal expansion due to the formation of different representative morphologies of extended irradiation-induced defects (vacancy and interstitial aggregates) and over a range of atomic displacement fractions. We find that, in addition to the simulation method reproducing the important mechanical and thermal properties of virgin graphite, the property changes caused by the formation of extended defects in the graphite crystal structure qualitatively agree with experimental observations at different irradiation/annealing temperature regimes. The results of these calculations provide a direct insight into how the underlying atomic scale defects and dislocations created by radiation damage can lead to material property changes, and demonstrate how this computationally efficient simulation method can be employed to reproduce crystallite changes in large-scale models of polygranular graphite. (C) 2015 Elsevier B.V. All rights reserved.

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