Effect of an electric field on the plastic deformation kinetics of electrodeposited Cu at low and intermediate temperatures

The plastic deformation kinetics of electrodeposited (EP) Cu foil with grain size d = 0.6 mum was determined at 293448 K without and with a concurrent electrostatic field E = 2.5kV/cm and compared with that for vapor-deposited (VP) Cu foil tested at 77-473 K without a field. The electric field produced a 20-25% decrease in the flow stress of the EP Cu. The apparent activation volume v = kTpartial derivativeIn(epsilon) over dot/partial derivativesigma both without and with electric field, exhibited a minimum at 350-375 K. The strain rate-controlling mechanism at Tless than or equal to5350K was concluded to be grain boundary shear promoted by the pile-up of dislocations at grain boundaries, while that at T = 373-473K was concluded to be the intersection of dislocations. The major effect of the electric field was to give a reduction in the dislocation density produced by straining, which was related to the electric charge density at the specimen surface. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.