Strong Strain Hardening in Nanocrystalline Nickel

X. L. Wu, Y. T. Zhu, Y. G. Wei, and Q. Wei

Phys. Rev. Lett. 103, 205504 – Published 13 November 2009

Abstract

Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show strong strain hardening in NC nickel with a grain size of $\sim 20 nm$ under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain interior. This is enabled primarily by Lomer-Cottrell locks, which pin the lock-forming dislocations and obstruct dislocation motion. These observations may help with developing strong and ductile NC metals and alloys.

Received 8 July 2009

DOI:https://doi.org/10.1103/PhysRevLett.103.205504

Authors & Affiliations

X. L. Wu^1,*, Y. T. Zhu^2,†, Y. G. Wei¹, and Q. Wei^3,‡

¹State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
²Department of Materials Science and Engineering, North Carolina State University, Raleigh, 27695, North Carolina, USA
³Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, North Carolina, 28223, USA

^*Corresponding author. xlwu@imech.ac.cn
^†ytzhu@ncsu.edu
^‡qwei@uncc.edu

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Vol. 103, Iss. 20 — 13 November 2009

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