Deformation mechanism transition caused by strain rate in a pulse electric brush-plated nanocrystalline Cu

Bulk nanocrystalline Cu was synthesized by a pulse electric brush-plating technique. A very large strength (at 2% plastic strain) increase from 644 to 1451 MPa was obtained by compression tests at room temperature and strain rates from 1 X 10(-5) to 3 X 10(0) s(-1). A transition in plastic deformation mechanism with strain rate from a combination of the thermally activated grain boundary sliding and the dislocation emission-absorption in grain boundaries to one dominated by the dislocation activity has been revealed by the significant changes in strain rate sensitivity and apparent activation volume with strain rate. (C) 2008 American Institute of Physics.