Size-Dependent Brittle-to-Ductile Transition in Silica Glass Nanofibers

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• 作者：Junhang Luo ; Jiangwei Wang ; Erik Bitzek ; Jian Yu Huang ; He Zheng ; Limin Tong ; Qing Yang ; Ju Li ; Scott X. Mao
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：January 13, 2016
• 年：2016
• 卷：16
• 期：1
• 页码：105-113
• 全文大小：628K
• ISSN：1530-6992

文摘

Silica (SiO₂) glass, an essential material in human civilization, possesses excellent formability near its glass-transition temperature (T_g > 1100 °C). However, bulk SiO₂ glass is very brittle at room temperature. Here we show a surprising brittle-to-ductile transition of SiO₂ glass nanofibers at room temperature as its diameter reduces below 18 nm, accompanied by ultrahigh fracture strength. Large tensile plastic elongation up to 18% can be achieved at low strain rate. The unexpected ductility is due to a free surface affected zone in the nanofibers, with enhanced ionic mobility compared to the bulk that improves ductility by producing more bond-switching events per irreversible bond loss under tensile stress. Our discovery is fundamentally important for understanding the damage tolerance of small-scale amorphous structures.