Finite-temperature non-equilibrium quasi-continuum analysis of nanovoid growth in copper at low and high strain rates
M. Ponga, M. Ortiz and M. P. Ariza
Mechanics of Materials, 90, 253-267 (2015).

ABSTRACT
We study dynamic nanovoid growth in copper single crystals under prescribed
volumetric strain rates ranging from moderate ((epsilon) over dot = 10(5) s(-1))
to high ((epsilon) over dot = 10(10) s(-1)). We gain access to lower strain
rates by accounting for thermal vibrations in an entropic sense within the
framework of maximum-entropy non-equilibrium statistical mechanics. We
additionally account for heat conduction by means of empirical atomic-level
kinetic laws. The resulting mean trajectories of the atoms are smooth and can be
integrated implicitly using large time steps, greatly in excess of those
required by molecular dynamics. We also gain access to large computational cells
by means of spatial coarse-graining using the quasicontinuum method. On this
basis, we identify a transition, somewhere between 10(7) and 10(8) s(-1) between
two regimes: a quasistatic regime characterized by nearly isothermal behavior
and low dislocation velocities; and a dynamic regime characterized by nearly
adiabatic conditions and high dislocation velocities. We also elucidate the
precise mechanisms underlying dislocation emission from the nanovoids during
cavitation. We additionally investigate the sensitivity of the results of the
analysis to the choice of interatomic potential by comparing two EAM-type
potentials.