Grain boundary sliding, triple junction disclinations and strain hardening in ultrafine-grained and nanocrystalline metals

被引：46
作者：
Ovid'ko, I. A. [1 ,2 ]
Sheinerman, A. G. [1 ,2 ]
机构：
[1] Peter Great St Petersburg Polytech Univ, St Petersburg 195251, Russia
[2] St Petersburg State Univ, Dept Math & Mech, St Petersburg 198504, Russia
来源：
INTERNATIONAL JOURNAL OF PLASTICITY | 2017年 / 96卷
关键词：
Grain boundaries; Ductility; Strengthening mechanisms; Polycrystalline material; DISLOCATION PILE-UPS; MECHANICAL-BEHAVIOR; ULTRAHIGH STRENGTH; MG ALLOY; DEFORMATION; SUPERPLASTICITY; DUCTILITY; NANOINDENTATION; TEMPERATURE; PARADOX;
D O I：
10.1016/j.ijplas.2017.05.005
中图分类号：
TH [机械、仪表工业];
学科分类号：
0802 ;
摘要：
A theoretical model is suggested which describes grain boundary (GB) sliding and its accommodation through dislocation slip in ultrafine-grained and nanocrystalline metals. The initial stage of the accommodating dislocation slip represents emission of lattice dislocations from triple junctions into grain interiors. The lattice dislocations emitted from a triple junction slip across a grain and are absorbed by an opposite GB where they are dissociated into GB dislocations that climb along the GB. In the situation where these GB sliding and accommodating processes are dominant, stress-strain dependences are calculated in ultrafine-grained copper. With the calculated dependences, we found that pronounced strain hardening occurs which is related to the accommodation processes and associated formation of disclinations at triple junctions of GBs. It is theoretically revealed that the special (new) strain hardening mechanism under discussion can play a significant role in enhancing ductility of ultrafine-grained and nanocrystalline metals at comparatively low temperatures. (C) 2017 Elsevier Ltd. All rights reserved.
引用
收藏
页码：227 / 241
页数：15
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