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SJTU Team Made Progress in Strain-Hardening in High-Strength Metals by Nanofiller Incorporation

September 17, 2018      Author: Shi Wenbo

Recently, the international leading nanoscience and nanotechnology journal, Nano Letters, has published online “Regain strain-hardening in high-strength metals by nanofiller incorporation at grain boundaries”, a seminal progress in the field of nanostructured metals and composites (DOI: 10.1021/acs.nanolett.8b02375). Shanghai Jiao Tong University is the first author affiliation of this paper. Co-first authors include Dr. Li Zan, an SJTU postdoctoral researcher, and Wang Haotian, a PhD candidate from Tsinghua University (THU). The research is the result of collaborative efforts by SJTU, THU and Brown University in USA. Corresponding authors of the paper are Prof.Zhang Di and Prof. Guo Qiang from SJTU State Key Laboratory of Metal Matrix Composites, and Prof. Li Xiaoyan from THU Department of Engineering Mechanics. Academician Prof. Gao Huajian from School of Engineering of Brown University is also an co-author of the paper.

The research was supported by National Key R&D Plan of Ministry of Science and Technology of China, National Natural Science Foundation of China and Science & Technology Commission of Shanghai Municipality.

Abstract: Grain refinement to the nano/ultrafine-grained regime can make metals several times stronger, but this process is usually accompanied by a dramatic loss of ductility. Such strength-ductility trade-off originates from a lack of strain-hardening capacity in tiny grains. Here, we present a strategy to regain the strain-hardening ability of high-strength metals by incorporation of extrinsic nanofillers at grain boundaries. We demonstrate that the dislocation storage ability in Cu grains can be considerably improved through this novel grain-boundary engineering approach, leading to a remarkably enhanced strain-hardening capacity and tensile ductility (uniform elongation). Experiments and large-scale atomistic simulations reveal that a key benefit of incorporated nanofillers is a reduction in the grain-boundary energy, enabling concurrent dislocation storage near the boundaries and in the Cu grain interior during straining. The strategy of grain-boundary engineering through nanofillers is easily controllable, generally applicable, and may open new avenues for producing nanostructured metals with extraordinary mechanical properties.

 

Translated by Zhang Qianqian