IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Tribology Wednesday Sessions
       Session TR+MM-WeA

Paper TR+MM-WeA10
Observation and Simulation of Dislocation Emission after Nanoindentation of an FCC (100) Surface

Wednesday, October 31, 2001, 5:00 pm, Room 132

Session: Nanotribology
Presenter: J. de la Figuera, Sandia National Laboratories
Authors: O. Rodríguez de la Fuente, Universidad Complutense de Madrid, Spain
J.A. Zimmerman, Sandia National Laboratories
J. de la Figuera, Sandia National Laboratories
M.A. González, Universidad Complutense de Madrid, Spain
J.C. Hamilton, Sandia National Laboratories
J.M. Rojo, Universidad Complutense de Madrid, Spain
Correspondent: Click to Email
The traditional use of indentation of materials to characterize mechanical hardness has benefited both from recent experimental and theoretical advances. The routine use of Scanning Probe Microscopes allows the detailed examination of the surface of materials after nanoindentation, using the same instrument for both deformation and analysis. Techniques used to model the defects generated during indentation have also advanced by the development of fast, parallel computations of million-atom systems governed by semi-empirical potential energy functions. Together, these advances are starting to bridge the gap between theory and experiment. We present a combined study of the emission of dislocation loops by indentation on the surface of Au(100) using Scanning Tunneling Microscope (STM) experiments and atomistic simulations employing the Embedded Atom Method (EAM). Our experiments show dislocation loops emitted in <110> directions that extend out to distances hundreds of nanometers away from the indentation region. These loops consist of dissociated edge loops that intersect the surface. The locations of these dissociated loops are identified by the sub-angstrom height hillocks observed on the crystal surface. Atomistic simulation of nanoindentation reveals that these dislocation loops are generated close to the indentation region and glide away along <110> directions. The sub-surface structure of the dislocation loops verifies the stacking faults beneath the hillocks, which intersect at a stair-rod dislocation. Our simulation permits an estimate of the Peierls barrier for loop glide, revealing why the dislocations can glide so far from the indentation region. We have also observed the same dislocation loops by annealing an ion-irradiated Au(100) surface. The atomistic simulations help to understand how the dislocation loops can withstand the annealing.