Atomistic simulation of fracture in UO2 under tensile loading

XF Tian and LQ Ge and Y Yu and Y Wang and ZJ You and LS Li, JOURNAL OF ALLOYS AND COMPOUNDS, 803, 42-50 (2019).

DOI: 10.1016/j.jallcom.2019.06.267

Density-functional-theory (DFT) calculations and molecular dynamics simulations were performed to resolve the fracture behavior in UO2 under tensile loading. By molecular dynamics simulation, potential dependence was identified on the existence of transient plastic deformation prior to intergranular fracture in polycrystalline UO2, so we further improved the Morelon interatomic potential based on GGA + U calculations to obtain reliable fracture behavior in UO2. Using the improved potential, the fracture behaviors in polycrystalline and single crystal UO2 under tensile loading were investigated. In polycrystalline UO2, brittle intergranular fracture was observed, and no phase transition was found. In single crystal, Fm (3) over barm - Pbcn and Fm (3) over barm-P4(2)/mnm structural transitions were observed under < 100 > tensile loading. The non-coherent interfaces between Pbcn and P4(2)/mnm phases play a critical role in microcrack formation. Under < 110 > tensile loading, only Fm (3) over barm-P4(2)/mnm transition was detected and the interface between Fm (3) over barm and P4(2)/mnm structures was coherent, so no crack was found until the end of the simulation with strain of 25% in < 100 > direction. (C) 2019 Elsevier B.V. All rights reserved.

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