Tensile and creep behavior of nickel nanowires containing volume defects: Insight into the deformation mechanisms and microstructural evolution using molecular dynamics simulations

Abstract

In this paper, we report the tensile and creep behavior of nickel nanowire (NW) containing volume defects (voids) using molecular dynamics (MD) simulations. The role of void (diameter = 30 Å) on the tensile deformation behavior and mechanisms is investigated at varying strain rates (108 s−1 – 1010 s−1) and temperatures (300 K–1200 K). Similarly, the creep properties are investigated at constant stresses in the range of 2 GPa–5 GPa, and temperatures in the range of 1000 K–1200 K. Embedded atom method (EAM) potential is used to model the interactions between nickel atoms. The NW model size used is 100 Å (x-axis) × 1000 Å (y-axis) × 100 Å (z-axis) and comprises of ∼920,000 atoms. Tensile results show that the load-bearing capacity, elastic modulus of the NWs have decreased with an increase in the number of voids. The microstructural investigations show that void acts as a source of dislocations and cause plastic strain in the NW. However, at higher temperatures, free surface edges act as the source of dislocations. Creep test results show that the strain rates in the steady-state region increase with the applied stress and temperature. The deformation mechanism is by diffusional creep in the steady-state region, and the stress exponent ‘n’ varies from 0.8 to 2.77. Microstructural investigations show the formation of stacking faults and twins. Based on the activation energy for creep, we observe that multi-void NW is less creep resistant than single void nickel NW.