High-tensile ductility in nanocrystalline copper

In this work we report a high-tensile ductility in a fully dense bulk nanocrystalline (nc) pure copper sample prepared by electrodeposition. A tensile ductility with an elongation to fracture of 30% was obtained in the nc Cu specimen with an average grain size of 27 nm, which is comparable to that for the coarse-grained polycrystalline Cu. An enhanced yield stress (119 MPa) and a depressed strain hardening exponent (0.22) were observed in the nc Cu sample with respect to the conventional polycrystalline Cu. The high-tensile ductility was attributed to the minimized artifacts in the nc sample, and the grain-boundary sliding deformation mechanism resulted from the numerous amount small-angle grain boundaries and the low microstrain (dislocation density).