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

Abstract

This paper reports the first quantitative measurement of a full spectrum of mechanical properties of five-fold 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 attributed to the increase 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. KEYWORDSfive-fold twin, size effect, Young's modulus, yield strength, ultimate tensile strength, strain hardening

The fundamentals of plastic deformation : several case studies of plasticity in confined volumes.

“…The type of plasticity observed in these materials, such as slip via perfect dislocations and deformation twinning appears to be dependent on both wire orientation as well as geometry. These findings, originally predicted by atomistic simulations, are being validated by a number of experiments on pristine nanowires [45,63,64,66,77,78,80].…”

Recent advances in nanorobotic manipulation inside scanning electron microscopes

“…Some notable achievements are mechanical and electrical characterization of graphene membranes 28,45 , electrical measurement of single transistors 27 , 3D transfer of graphene 28,45 , assembly of photonic crystal devices 1,187 , identification of the size effect on the mechanical properties of nanowires and the strain effect on the piezoresistive properties of nanowires 51,162 , discovery of new gene loci associated with promyelocytic nuclear bodies 37 , and tracing of neuronal networks and synaptic connections 182,183 . The formation of hybrid systems by integrating other instruments into an SEM has also produced unique capabilities.…”

“…Mechanical characterization of nanomaterials has significantly benefited from SEM in situ nanomanipulation. For instance, nanomanipulation and tensile testing of Ag nanowires of different diameters revealed quantitatively the size and structure effects on the nanowire's mechanical properties (that is, Young's modulus, yield strength, and ultimate tensile strength) 51 . Nanomanipulation was also conducted to perform measurements on silicon nanowires 177 and CNTs 50,137 to Mechanical testing Nanomaterials Young's modulus, yield strength, and ultimate tensile strength of Ag NWs increased as the diameter decreased.…”

“…Piezoelectric actuators that are governed by the inverse piezoelectric effect overcome these challenges 47,48 and are capable of generating large forces in the kilo-Newton range with subnanometer positioning resolution and a high bandwidth 49 . A number of piezoelectric actuator-based nanomanipulators with multiple DOFs have been developed for precise positioning and manipulation of micro-and nanoscaled objects by companies (for example, Zyvex, Kleindiek, SmarAct, Toronto Nanoinstrumentation, and Attocube) and academia 33,41,42,[50][51][52][53][54] . The most common configuration of actuators for nanomanipulation is a coarse and fine positioner combination or a single actuator for both coarse and fine positioning.…”

“…Mechanical characterization of onedimensional nanomaterial was also conducted via tensile testing by two AFM cantilevers 50,137 . Using this approach, Zhu et al conducted in situ tensile testing of a silver nanowire for mechanical characterization of its Young's modulus, yield strength, and ultimate tensile strength 51 , as shown in Figure 4b. An InGaAs/GaAs nanospring was stretched for tensile tests using a similar method to determine its stiffness 157,158 (refer to Figure 4c).…”