Atomistic simulations of the deformation behavior of an Nb nanowire embedded in a NiTi shape memory alloy

TL;DR

This study uses molecular dynamics simulations to explore how pre-strain and temperature affect the deformation behavior of Nb nanowires embedded in NiTi shape memory alloys, revealing unique elastic and hysteresis properties.

Contribution

A new Nb-Ni-Ti interatomic potential is developed and used to uncover the mechanisms behind quasi-linear elasticity, slim hysteresis, and Young's modulus reduction in nanowire-SMA composites.

Findings

Plastic deformation in Nb nanowires is crucial for observed phenomena.

Pre-straining can tune Young's modulus across various temperatures.

A descriptor for monitoring Young's modulus evolution is proposed.

Abstract

The influence of pre-strain and temperature on the superior properties exhibited by an Nb nanowire embedded in a NiTi shape memory alloy (SMA) are investigated via molecular dynamics simulations. To this end, a new Nb-Ni-Ti ternary interatomic potential based on the second nearest-neighbor modified embedded-atom method (2NN MEAM) is developed and employed. The origin of the unique phenomena of quasi-linear elasticity, slim hysteresis, and reduction in Young's modulus observed for pre-strained nanowire-SMA composites is uncovered. The results demonstrate the importance of plastic deformation in the embedded Nb nanowires and reveal how the deformation facilitates the just-mentioned, unprecedented phenomena. A simple and straightforwardly obtainable descriptor to correlate and monitor Young's modulus evolution during pre-straining is proposed. Furthermore, our simulations suggest that the desired Young's modulus can be obtained for a wide range of application temperatures through appropriate pre-straining.