Molecular dynamics simulations of intergranular fracture in UO2 with nine empirical interatomic potentials

YF Zhang and PC Millett and MR Tonks and XM Bai and SB Biner, JOURNAL OF NUCLEAR MATERIALS, 452, 296-303 (2014).

DOI: 10.1016/j.jnucmat.2014.05.034

The intergranular fracture behavior of UO2 was studied using molecular dynamics simulations with a bicrystal model. The anisotropic fracture behavior due to the different grain boundary characters was investigated with the < 100 > symmetrical tilt Sigma 5 and the < 110 > symmetrical tilt Sigma 3 (111 twin) grain boundaries. Nine interatomic potentials, seven rigid-ion plus two core-shell ones, were utilized to elucidate possible potential dependence. Initiating from a notch, crack propagation along grain boundaries was observed for most potentials. The Sigma 3 boundary was found to be more prone to fracture than the Sigma 5 one, indicated by a lower energy release rate associated with the former. However, some potential dependence was identified on the existence of transient plastic deformation at crack tips, and the results were discussed regarding the relevant material properties including the excess energies of metastable phases and the critical energy release rate for intergranular fracture. In general, local plasticity at crack tips was observed in fracture simulations with potentials that predict low excess energies for metastable phases and high critical energy release rates for intergranular fracture. (C) 2014 Elsevier B.V. All rights reserved.

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