Elastic properties of grain boundaries in copper and their relationship to bulk elastic constants

The pressure derivatives and uniaxial strain derivatives of the elastic constants of copper are calculated using the embedded-atom method, and the results are in good agreement with experiment. Also, the elastic constants of a 5 twist grain boundary [with (100) boundary planes] are calculated on a layer-by-layer basis, and the elastic behavior is shown to differ by up to an order of magnitude from bulklike behavior. This unusual elastic behavior is found to be similar to that of uniaxially strained crystals, since the grain boundaries themselves are regions that are strained (expanded) in one direction.