Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale
Author(s)
Qi, Liang; Li, Ju; Yu, Qian; Mishra, Raja K.; Minor, Andrew M.
DownloadQi-2013-Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale.pdf (981.6Kb)
PUBLISHER_POLICY
Publisher Policy
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Terms of use
Metadata
Show full item recordAbstract
In mechanical deformation of crystalline materials, the critical resolved shear stress (CRSS; τ[subscript CRSS]) is the stress required to initiate movement of dislocations on a specific plane. In plastically anisotropic materials, such as Mg, τ[subscript CRSS] for different slip systems differs greatly, leading to relatively poor ductility and formability. However, τ[subscript CRSS] for all slip systems increases as the physical dimension of the sample decreases to approach eventually the ideal shear stresses of a material, which are much less anisotropic. Therefore, as the size of a sample gets smaller, the yield stress increases and τ[subscript CRSS] anisotropy decreases. Here, we use in situ transmission electron microscopy mechanical testing and atomistic simulations to demonstrate that τ[subscript CRSS] anisotropy can be significantly reduced in nanoscale Mg single crystals, where extremely high stresses (~2 GPa) activate multiple deformation modes, resulting in a change from basal slip-dominated plasticity to a more homogeneous plasticity. Consequently, an abrupt and dramatic size-induced “brittle-to-ductile” transition occurs around 100 nm. This nanoscale change in the CRSS anisotropy demonstrates the powerful effect of size-related deformation mechanisms and should be a general feature in plastically anisotropic materials.
Date issued
2013-08Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering; Massachusetts Institute of Technology. Department of Nuclear Science and EngineeringJournal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Yu, Q., L. Qi, R. K. Mishra, J. Li, and A. M. Minor. “Reducing Deformation Anisotropy to Achieve Ultrahigh Strength and Ductility in Mg at the Nanoscale.” Proceedings of the National Academy of Sciences 110, no. 33 (August 13, 2013): 13289–13293.
Version: Final published version
ISSN
0027-8424
1091-6490