Defence Science Journal, Vol. 59, No. 3, May 2009, pp.
252-259
© 2009, DESIDOC
Effects of
Isothermal and Adiabatic Thermal Loadings on Size and
Strain Rate
Dependence of Copper Nanowire
Vijay Kumar Sutrakar1 and
D. Roy Mahapatra2
1Aeronautical Development Establishment, Bangalore-560
075
2Indian Institute of Science, Bangalore-560 012
ABSTRACT
In the present paper, the
size and strain rate effects on ultra-thin <100>/{100} Cu nanowires at an
initial temperature of 10 K have been discussed. Extensive molecular dynamics
(MD) simulations have been performed using Embedded atom method (EAM) to
investigate the structural behaviours and properties under high strain rate.
Velocity-Verlet algorithm has been used to solve the equation of motions. Two
different thermal loading cases have been considered: (i) Isothermal loading,
in which Nose-Hoover thermostat is used to maintain the constant system
temperature, and (ii) Adiabatic loading, i.e., without any thermostat. Five
different wire crosssections were considered ranging from 0.723 x 0.723 nm2 to 2.169 x 2.169
nm2.
The strain rates used in the present study were 1 x 109 s-1, 1 x 108 s-1, and 1 x 107 s-1. The effect of
strain rate on the mechanical properties of copper nanowires was analysed,
which shows that elastic properties are independent of thermal loading for a
given strain rate and cross-sectional dimension of nanowire. It showed a
decreasing yield stress and yield strain with decreasing strain rate for a
given cross-section. Also, a decreasing yield stress and increasing yield
strain were observed for a given strain rate with increasing cross-sectional
area. Elastic modulus was found to be ~100 GPa, which was independent of
processing temperature, strain rate, and size for a given initial temperature. Reorientation
of <100>/ {100} square cross-sectional copper nanowires into a series of
stable ultra-thin pentagon copper nanobridge structures with dia of ~ 1 nm at
10 K was observed under high strain rate tensile loading. The effect of
isothermal and adiabatic loading on the formation of such pentagonal nanobridge
structure has been discussed.
Keywords: Metallic nanowires, sensors, nanosystems, copper
nanowires, nanobridge structure, moleculer dynamics simulation, nano-electronic
device fabrication, isothermal loading, thermal loading, adiabatic thermal
loading.