Nucleation‐Controlled Distributed Plasticity in Penta‐twinned Silver Nanowires

Abstract

A unique size-dependent strain hardening mechanism, that achieves both high strength and ductility, is demonstrated for penta-twinned Ag nanowires (NWs) through a combined experimental-computational approach. Thin Ag NWs are found to deform via the surface nucleation of stacking fault decahedrons (SFDs) in multiple plastic zones distributed along the NW. Twin boundaries lead to the formation of SFD chains that locally harden the NW and promote subsequent nucleation of SFDs at other locations. Due to surface undulations, chain reactions of SFD arrays are activated at stress concentrations and terminated as local stress decreases, revealing insensitivity to defects imparted by the twin structures. Thick NWs exhibit lower flow stress and number of distributed plastic zones due to the onset of necking accompanied by more complex dislocation structures.

Nanotwinned silver nanowires: Structure and mechanical properties

“…4 reveal a 3-10 times higher yield strength (r 1 ¼ 480 MPa, r 2 ¼ 700 MPa) compared to polycrystalline bulk Ag (r yield ¼ 50 MPa) [61]. A similar increased strength has been reported for fivefold twinned Ag NWs [52,62] as well as for nanocrystalline or nanotwinned polycrystals [11,22,63,64]. To assess which strengthening contribution is dominant in the presented nanotwinned nanowires, the results of our tensile tests are compared to the normalized resolved yield stress of NWs and nanocrystalline and nanotwinned microcrystalline fcc metals (Fig.…”

Double-tilt in situ TEM holder with multiple electrical contacts and its application in MEMS-based mechanical testing of nanomaterials

“…6g. The modulus of the specimen is 91 GPa (computed with the data up to 1% strain), which agrees well with our previous results in this material [21] that indicate a size effect i.e. an increase of the modulus with respect to the bulk value (84 GPa) [22].…”

“…Furthermore, we carried out a tensile test for a 73 nm-diameter penta-twinned silver nanowire. These nanowires are composed of five single-crystal domains, oriented on the 〈110〉 directions, and intersecting at {111} twin planes (for more details about the crystal structure see [21]). As such, the obtained diffraction pattern (Fig.…”

Surface effects on the initial dislocation of Ag nanowires

“…The effects of strain rate, crystal size and system temperature on the mechanical properties have been intensely studied [5][6][7][8][9][10][11][12]. The surface and interface stresses can be dominant factors in determining the equilibrium structure when the dimensions of nano materials are smaller than 10 nm [13,14].…”