Table of Contents
Volume 550 Number 7677 pp429-554
26 October 2017
This Week
News In Focus
Specials
Research
About the cover
The cover shows an intricate network of lattice defects — dislocation lines — whose motion makes metal tantalum flow under compression. Fully dynamic atomistic simulations of plastic deformation in metals are extremely demanding computationally and usually involve mesoscale approximations. In this issue, Vasily Bulatov and his colleagues present fully dynamic atomic-level simulations of metal plasticity that feature up to 268 million atoms, each such simulation generating around 2 exabytes (1 exabyte = 1018 bytes) of data. Using their model, the authors probe how body-centred-cubic metal tantalum responds to ultrahigh-strain-rate deformation. They find that on reaching certain limiting conditions, dislocations can no longer relieve mechanical loads and twinning — the sudden reorientation of the crystal lattice — takes over. They also find that below such critical conditions, flow stress and dislocation density achieve a steady state in which the metal can be kneaded indefinitely like a piece of dough. Cover image: Alexander Stukowski
