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  • Ceramic Nanowires:Brittle of Ductile, Why?
    Author:Jun Wang   | Date:2012-02-09   | Click Rate:    | 【Close

    Recently Dr. Jun Wang et al published their work in Nanotechnology, 23 (2012), 025703. This article reveals the mechanism governing the large plastic deformation of SiC nanowires (NWs), which was experimentally observed at room temperature. Due to this significant progress, this paper has been selected in Institute of Physics (IOP) Select. Also, the website Nanotechweb.org introduces this paper at its Lab Talk forum (http://nanotechweb.org/cws/article/lab/48202).

    The collaborative research was performed by an international team consisting of researchers from the State Key Laboratory of Nonlinear Mechanics, Chinese Academy of Sciences, Australia (Curtin University & University of Sydney), China (Beihang University & City University of Hong Kong) and US (Brown University).

    IOP states that IOP Select is a special collection of journal articles, chosen by IOP’s Editors based on one or more of the following criteria: Substantial advances or significant breakthrough, A high degree of novelty, Significant impact on future research.

    Following is the news in Lab Talk forum at Nanotechweb.org

    Dec 23, 2011

    At the macroscopic scale, ceramics are brittle at room temperature, but novel findings emerge when the characteristic dimension of the structures is reduced to the nanoscale. For example, large plastic deformation of SiC NWs has recently been observed in the lab, but unfortunately most theoretical analysis reveals only the elastic behavior and brittle failure. Researchers from Australia (Curtin University, University of Sydney), China (Beihang University, Chinese Academy of Sciences, City University of Hong Kong) and the US (Brown University) have teamed up to help to fill in some of the missing detail.

    The scientists noted that microstructures of SiC NWs synthesized in laboratories usually consist of cubic-structured segments, stacking defects, twins and intergranular amorphous films. These structures exhibit various side morphologies, as shown in the figure, where transmission electron microscope (TEM) image was adapted from Adv. Funct. Mater. 17 (2007) 3435.

    Based on molecular dynamics simulations, it is shown that the large plastic deformation occurs as a result of the anti-parallel sliding of cubic-structured grains along intergranular amorphous films inclined at an angle of 19.47º with respect to the NW axis. The ductile behavior is thermally stable below 700 K. Also revealed is the wide dispersion of mechanical properties such as Young’s modulus, strength and elongation due to the anisotropy of the microstructures. The group’s results offer guidance on the microstructural design of ceramics with tailored mechanical properties.

     

    Microstructures in SiC NWs. TEM image was adapted from Adv. Funct. Mater. 17 (2007) 3435.

    This work has been supported by the National Basic Research Program of China (2007CB814803), the National Natural Science Foundation of China (Grant Nos. 11172024, 10732090, 10932011, 11072014, 10972218 and 11021262), the Australian Research Council (DP0985450) and the U.S. National Science Foundation (CMMI-0758535).

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