Digital Repository, ICF12, Ottawa 2009

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Thermally-Activated Plasticity at the Atomic Scale
D. Rodney

Last modified: 2012-10-03


Plasticity and fracture are strongly affected when dislocation glide or nucleationare thermally-activated. Such processes are difficult to study from atomic-scalesimulations because they are stochastic with waiting times that rapidly exceedthe simulation time when the temperature decreases. Here, we review recentresults obtained by a combination of molecular static (MS) and dynamic (MD)simulations. We consider the thermally-activated glide of dislocations in highPeierls stress crystals where the dislocation velocity is expected to dependexponentially on the kink-pair activation enthalpy. We verify the validity of thisrelation and compute the pre-exponential factor by comparing MD simulations tostatic Nudged Elastic Band method calculations of the activation enthalpy. Theactivation enthalpy versus applied stress curve is analyzed using a line tensionmodel of a dislocation moving on a stress-dependent substrate potential. Resultsare discussed and compared to experimental data on the temperaturedependence of the flow stress.

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