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“單晶突然折斷時(shí)會產(chǎn)生孿晶” 已有1人參與
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單晶突然折斷時(shí)會產(chǎn)生孿晶 http://paper.sciencenet.cn//htmlpaper/201191416185575319259.shtm 易碎的金子。(圖片提供:Lou實(shí)驗(yàn)室/美國得克薩斯州萊斯大學(xué)) 金線的厚度足以保證它能夠在你的手中被彎曲和拉伸,這也使其在電子設(shè)備中具有重要的使用價(jià)值。 然而,美國得克薩斯州萊斯大學(xué)的材料學(xué)家Jun Lou和同事在9月份出版的《先進(jìn)功能材料》(Advanced Functional Materials )雜志中報(bào)告說,如果將金線拉伸得太細(xì)——其直徑不足20納米——這種金屬將變得非常易碎。 當(dāng)研究人員將拉伸得到的單晶金線放大以進(jìn)行詳細(xì)研究時(shí),他們發(fā)現(xiàn),這些易碎的單晶在突然折斷時(shí)并非如此“孤單”。它們會自然地產(chǎn)生“孿晶”。 孿晶會共享一些原子,但是它們整體的晶體結(jié)構(gòu)卻能夠彼此抵消(圖中黃線所示)。 當(dāng)金線被拉伸后,整個(gè)原子團(tuán)會滑入不同的位置以減輕應(yīng)力并產(chǎn)生孿晶。 隨著金線被拉伸得越來越細(xì),它便會一而再、再而三地產(chǎn)生孿晶。這些金線最終會沿著孿晶之間的一個(gè)平面,以一種易碎的方式斷裂。 研究人員表示,這一發(fā)現(xiàn)將迫使工程師們在納米電子學(xué)研究中更加慎重地對待金線,或者徹底用一種完全不同的材料加以替代。(來源:科學(xué)時(shí)報(bào) 趙路) Fracture of Sub‐20nm Ultrathin Gold Nanowires Keywords:gold nanowires;fracture;in‐situ TEM Abstract: Fracture of metals at the nanoscale and corresponding failure mechanisms have recently attracted considerable interest. However, quantitative in situ fracture experiments of nanoscale metals are rarely reported. Here it is shown that, under uni‐axial tensile loading, single crystalline ultrathin gold nanowires may fracture in two modes, displaying distinctively different fracture morphologies and ductility. In situ high resolution transmission electron microscopy (HRTEM) studies suggest that the unexpected brittle‐like fracture was closely related to the observed twin structures, which is very different from surface dislocation nucleation/propagation mediated mechanism in ductile fracture mode. Molecular dynamics (MD) simulations further reveal the processes of shear‐induced twin formation and damage initiation at the twin structure/free surface interface, confirming the experimentally observed differences in fracture morphology and ductility. Finally, a fracture criterion based on competition between twin formation and surface dislocation nucleation/propagation as a function of misalignment angle is discussed. 作 者:Lu, Yang; Song, Jun; Huang, Jian Yu; Lou, Jun 期刊名稱: Advanced Functional Materials 期卷頁: 24 AUG 2011 第卷 第期 ~頁 學(xué)科領(lǐng)域:工程材料 » 金屬材料 » 金屬材料的力學(xué)行為 原文鏈接:http://onlinelibrary.wiley.com/d ... .201101224/abstract DOI: 10.1002/adfm.201101224 ISBN: 1616-3028 關(guān)鍵詞: gold nanowires; fracture;in-situ TEM 相關(guān)報(bào)道: http://paper.sciencenet.cn/htmlpaper/201191416185575319259.shtm |
材料學(xué)前沿、發(fā)現(xiàn)、猜想 | 微納米力學(xué) |

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