Dislocation drag at the nanoscale

The mobility of dislocations is shown to be a size-dependent phenomenon. When dislocations intersect free surfaces, the mobility decreases as the dislocation length decreases, suggesting that dislocation motion in small structures may be more difficult. This increased drag may be related to surface forces acting where the dislocation intersects the free surface or from altered dislocation-phonon interactions. Mobility, however, is not as dependent on the film thickness and converges rapidly to bulk values. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.