Irreversibility of dislocation motion under cyclic loading due to strain gradients

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• 作者：Markus Stricker^a ; Daniel Weygand^a ; ^{daniel.weygand@kit.edu} ; Peter Gumbsch^a ; ^b
• 关键词：Irreversibility ; Plasticity ; Dislocation structure ; Bending ; Torsion
• 刊名：Scripta Materialia
• 出版年：2017
• 出版时间：1 March 2017
• 年：2017
• 卷：129
• 期：Complete
• 页码：69-73
• 全文大小：636 K
• 卷排序：129

文摘

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.