Dislocation Dynamics in Nanocrystalline Nickel

Z. W. Shan, Department of Mechanical Engineering, University of Pittsburgh
J. M. K. Wiezorek, Department of Materials Science and Engineering, University of Pittsburgh
E A. Stach, Birck Nanotechnology Center and School of Materials Engineering, Purdue University
D. M. Follstaedt, Physical and Chemical Sciences Center, Sandian National Laboratories
J. A. Knapp, Physical and Chemical Sciences Center, Sandia National Laboratories
S. X. Mao, Department of Mechanical Engineering, University of Pittsburgh

Abstract

It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains as small as 5 nm, but subsequent relaxation leads to dislocation recombination.