Repulsive force of twin boundary on curved dislocations and its role on the yielding of twinned nanowires

The effects of twin size and sample diameter on yield stress and surface dislocation emission in twinned metal nanowires deformed uniformly were studied using classical dislocation theory and the concept of image force from twin boundaries. This theoretical study is shown to quantitatively capture the linear increase in yield stress as twin size decreases in periodically twinned Au nanowires predicted by atomistic simulations. The implication of this model as a yield criterion for realistic metal nanostructures with nanoscale growth twins is discussed. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.