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Irreversibility of dislocation motion under cyclic loading due to strain gradients

: Stricker, M.; Weygand, D.; Gumbsch, P.

Preprint urn:nbn:de:0011-n-4357578 (773 KByte PDF)
MD5 Fingerprint: 7916ba26559d8eb4509e26f5936c61f1
Created on: 09.11.2018

Scripta materialia 129 (2017), pp.69-73
ISSN: 1359-6462
Deutsche Forschungsgemeinschaft DFG
Journal Article, Electronic Publication
Fraunhofer IWM ()
irreversibility; plasticity; dislocation structure bending; Torsion

Mechanisms that make dislocation motion irreversible are associated with the formation of dislocation junctions and cross-slip, leaving dislocations trapped inside the specimen. Using Discrete Dislocation Dynamics simulations, we identify another mechanism that produces irreversible plastic deformation and leaves no or only very few dislocations inside the sample: Under cyclic loading, dislocations which pass the neutral plane during loading (pile-up formation), generate a slip step upon unloading. The explanation is an intrinsic asymmetry between the backward and forward motion. An additional bias may be introduced by the geometry of the specimen due to the shortening of the line length of dislocations.