Coupled effect of size, strain rate, and temperature on the shape memory of a pentagonal Cu nanowire

Abstract

A body-centered pentagonal nanobridge structure with lattice constants c = 2.35 and a = 2.53 A has been observed under high strain rate tensile loading on an initially constrained [Formula: see text] Cu nanowire at various temperatures. Extensive molecular dynamics (MD) simulations have been performed using the embedded atom method (EAM) for cross-sectional dimensions ranging from 0.723 x 0.723 to 2.169 x 2.169 nm(2), temperature ranging from 10 to 600 K, and strain rates of 10(9)-10(7) s(-1). Formations of such pentagonal nanowire are observed for a temperature range 200-600 K for particular cross-sectional dimensions and strain rates. A large inelastic deformation of approximately 50% is obtained under both isothermal loading and adiabatic loading. With very high degree of repeatability of such pentagonal nanowire formation, the present findings indicate that the interesting stability property and high strength of elongated nanowires have various potential applications in nanomechanical and nanoelectronic devices. Further, we demonstrate a novel thermomechanical unloading mechanism by which it is possible to impart recovery from a pentagonal nanowire following a hysteresis loop: [Formula: see text].

On the stress‐strain curves in gold and aluminum nanowires

“…As pointed out in [18] the deformation mechanisms depend on the nanowire width: while in the largest structures the deformation is dominated by dislocations, in very small sizes surface effects prevail. It is worth noting that no pentagonal structures such as those observed upon stretching Cu nanowires [26][27][28] were identified.…”

Single and multi-step phase transformation in CuZr nanowire under compressive/tensile loading

“…Recently, Molecular Dynamics (MD) simulations have been performed extensively to obtain material properties including phase transformation behavior at nano-scale. For example, a face-centered-cubic (FCC) to body-centered-tetragonal (BCT) phase transformation in gold nanowires [14], from FCC to pentagonal structure in Cu nanowires [15,16], and B2 to BCT phase transformation in NiAl nanowires [17] have been observed. Atomistic simulations using Cu-Zr binary alloy have also been performed extensively in the recent years.…”

Asymmetry in structural and thermo-mechanical behavior of intermetallic NiAl nanowire under tensile/compressive loading: A molecular dynamics study

“…For example, surface-stress driven phase transformation from face-centered-cubic (FCC) to body-centeredtetragonal (BCT) in gold nanowires [11], FCC to pentagonal in Cu nanowires [12,13], and B2 to BCT in CueZr nanowire [14] have been observed under high strain rate tensile loading. Tensionecompression asymmetry is also reported for single crystal Cu in Ref.…”