Title

Dislocation Dynamics Simulations of the Bauschinger Effect in Metallic Thin Films

Abstract

Three-dimensional dislocation dynamics simulations were used to examine the role of surface passivation on the plasticity of thin films. A simple line-tension model was used to model the dislocation transmission cross grain boundaries. We find that passivated thin films have a higher hardening rate and strength than freestanding films and that the hardening rate increases with decreasing film thickness. Under unloading, passivated films exhibit a significant Bauschinger effect in which reverse plastic flow occurs during unloading. The Bauschinger effect is enhanced by an increasing pre-strain or by decreasing the aspect ratio of the film. The reverse motion of dislocation pile-ups and the collapse of misfit dislocations were found to be responsible for the observed Bauschinger effect in passivated films. The predicted deformation behavior is in excellent agreement with that seen experimentally.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Bauschinger Effect; Grain Boundaries; Passivation Layer; Deformation Behavior; Dislocation Dynamics Simulation; Freestanding Films; Metallic Thin Films; Passivated Film; Pile-Ups; Pre-Strain; Rate Increase; Surface Passivation

International Standard Serial Number (ISSN)

9270256

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 Elsevier, All rights reserved.

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