Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale

Yu Q.; Qi L.; Mishra R.K.Li J.Minor A.M.

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Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale

机译：Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale

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摘要

In mechanical deformation of crystalline materials, the critical resolved shear stress (CRSS; tCRSS) is the stress required to initiate movement of dislocations on a specific plane. In plastically anisotropic materials, such as Mg, tCRSS for different slip systems differs greatly, leading to relatively poor ductility and formability. However, tCRSS 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 tCRSS anisotropy decreases. Here, we use in situ transmission electron microscopy mechanical testing and atomistic simulations to demonstrate that tCRSS 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 "brittleto- ductile" transition occurs around 100 nm. This nanoscale change in the CRSS anisotropy demonstrates the powerful effect of sizerelated deformation mechanisms and should be a general feature in plastically anisotropic materials.

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《Proceedings of the National Academy of Sciences of the United States of America》 |2013年第33期|13289-13293|共5页
作者
Yu Q.; Qi L.; Mishra R.K.Li J.Minor A.M.;
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作者单位

Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, United States;

Departments of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States;

General Motors Research and Development Center, Warren, MI 48090, United States;

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收录信息美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
原文格式 PDF
正文语种英语
中图分类自然科学总论;
关键词
In situ TEM; Lightweight alloys; Mechanical properties; Metallurgy; Nanoparticle;

Reducing deformation anisotropy to achieve ultrahigh strength and ductility in Mg at the nanoscale

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