Plastic deformation of freestanding thin films: Experiments and modeling Academic Article uri icon

abstract

  • Experimental measurements and computational results for the evolution of plastic deformation in freestanding thin films are compared. In the experiments, the stress-strain response of two sets of Cu films is determined in the plane-strain bulge test. One set of samples consists of electroplated Cu films, while the other set is sputter-deposited. Unpassivated films, films passivated on one side and films passivated on both sides are considered. The calculations are carried out within a two-dimensional plane strain framework with the dislocations modeled as line singularities in an isotropic elastic solid. The film is modeled by a unit cell consisting of eight grains, each of which has three slip systems. The film is initially free of dislocations which then nucleate from a specified distribution of Frank-Read sources. The grain boundaries and any film-passivation layer interfaces are taken to be impenetrable to dislocations. Both the experiments and the computations show: (i) a flow strength for the passivated films that is greater than for the unpassivated films and (ii) hysteresis and a Bauschinger effect that increases with increasing pre-strain for passivated films, while for unpassivated films hysteresis and a Bauschinger effect are small or absent. Furthermore, the experimental measurements and computational results for the 0.2% offset yield strength stress, and the evolution of hysteresis and of the Bauschinger effect are in good quantitative agreement. © 2006 Elsevier Ltd. All rights reserved.

published proceedings

  • Journal of the Mechanics and Physics of Solids

author list (cited authors)

  • Nicola, L., Xiang, Y., Vlassak, J. J., Van der Giessen, E., & Needleman, A

citation count

  • 183

complete list of authors

  • Nicola, L||Xiang, Y||Vlassak, JJ||Van der Giessen, E||Needleman, A

publication date

  • October 2006