Size effects on elasticity, yielding, and fracture of silver nanowires: In situ experiments

Yong Zhu, Qingquan Qin, Feng Xu, Fengru Fan, Yong Ding, Tim Zhang, Benjamin J. Wiley, and Zhong Lin Wang

Phys. Rev. B 85, 045443 – Published 30 January 2012

Abstract

This paper reports the quantitative measurement of a full spectrum of mechanical properties of fivefold twinned silver (Ag) nanowires (NWs), including Young's modulus, yield strength, and ultimate tensile strength. In-situ tensile testing of Ag NWs with diameters between 34 and 130 nm was carried out inside a scanning electron microscope (SEM). Young's modulus, yield strength, and ultimate tensile strength all increased as the NW diameter decreased. The maximum yield strength in our tests was found to be 2.64 GPa, which is about 50 times the bulk value and close to the theoretical value of Ag in the $〈110〉$ orientation. The size effect in the yield strength is mainly due to the stiffening size effect in the Young's modulus. Yield strain scales reasonably well with the NW surface area, which reveals that yielding of Ag NWs is due to dislocation nucleation from surface sources. Pronounced strain hardening was observed for most NWs in our study. The strain hardening, which has not previously been reported for NWs, is mainly attributed to the presence of internal twin boundaries.

Received 31 August 2011

DOI:https://doi.org/10.1103/PhysRevB.85.045443

Authors & Affiliations

Yong Zhu^1,*, Qingquan Qin¹, Feng Xu¹, Fengru Fan², Yong Ding², Tim Zhang³, Benjamin J. Wiley³, and Zhong Lin Wang²

¹Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
²School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
³Department of Chemistry, Duke University, Durham, North Carolina 27708, USA

^*Corresponding author: Department of Mechanical & Aerospace Engineering, NCSU, 911 Oval Dr., Raleigh, NC 27695; yong_zhu@ncsu.edu

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Vol. 85, Iss. 4 — 15 January 2012

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