Glide mobility of the 1/2 1101(001) edge dislocation in UO2 from molecular dynamics simulation

AV Lunev and AY Kuksin and SV Starikov, INTERNATIONAL JOURNAL OF PLASTICITY, 89, 85-95 (2017).

DOI: 10.1016/j.ijplas.2016.11.004

Both the mechanical properties of oxide nuclear fuel and the high burn- up grain restructuring are known to be related to dislocation motion. Previous studies show that at temperatures above 1000 K slip on 001) crystallographic planes in UO2 is dominant, and 1/2(110)(001 dislocations should have the highest mobility. However, no information is available on the temperature and stress dependence of dislocation velocities in UO2. This information is required as input in higher scale simulation techniques, such as dislocation dynamics, to gain an insight into the unusual plastic behaviour of this oxide. In this study we employed molecular dynamics to gather a representative set of data on the 1/2(110) (001) dislocation motion in UO2 at temperatures from 1000 to 2000 K and shear stress from 25 to 1000 MPa. We found that dislocation motion was thermally activated, with two distinct modes of motion. Based on this knowledge, we selected an analytic expression for dislocation velocity and performed fitting to MD data. This expression described the simulation data well, and was also used to make a physically justified prediction for dislocation velocities at typical operating conditions of the oxide nuclear fuel. (C) 2016 Elsevier Ltd. All rights reserved.

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