Modeling grain size dependent optimal twin spacing for achieving ultimate high strength and related high ductility in nanotwinned metals

Linli Zhu, Haihui Ruan, Xiaoyan Li, Ming Dao, Huajian Gao, Jian Lu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

156 Citations (Scopus)

Abstract

We have developed a mechanism-based plasticity model of nanotwinned metals to investigate the effect of twin spacing on strength, ductility and work hardening rate of such materials. In particular, the unique roles of dislocation pile-up zones near twin and grain boundaries, as well as twinning partial dislocations, in strengthening and work hardening are incorporated in the model. Competition between different local failure mechanisms associated with twin lamellae and/or grain boundaries is considered in evaluating the tensile ductility of nanotwinned metals. The present study provides a quantitative continuum plasticity model capable of describing the variations in strength, ductility and work hardening rate of nanotwinned metals with the twin spacing. For nanotwinned copper a grain size of 500 nm, the model predicts a critical twin spacing for the maximum strength at 13 nm, in excellent agreement with experimental observations. The critical twin spacing is found to be linearly proportional to the grain size, which is consistent with recent molecular dynamics simulations.
Original languageEnglish
Pages (from-to)5544-5557
Number of pages14
JournalActa Materialia
Volume59
Issue number14
DOIs
Publication statusPublished - 1 Aug 2011

Keywords

  • Density of dislocations
  • Dislocation pile-up zone
  • Ductility
  • Nanotwinned metal
  • Strength

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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