Strain rates in molecular dynamics simulations of nanocrystalline metals
Christian Brandl, Peter M Derlet, Helena Van Swygenhoven
PHILOSOPHICAL MAGAZINE | TAYLOR & FRANCIS LTD | Published : 2009
To study deformation mechanisms using molecular dynamics, very high strain rates have to be applied. The effect of lowering the strain rate by two orders of magnitude on the deformation characteristics of nanocrystalline Al was investigated. For the highest strain rate, the onset of dislocation propagation is delayed, resulting in a stress overshoot. With decreasing strain rate the grain-averaged resolved shear stress reduces and cross-slip occurs more frequently. However, even at the lowest applied strain rate the grain boundary network can not accommodate all arriving dislocations, illustrating the challenge to determine the rate-limiting deformation mechanisms for experimental conditions.
Awarded by European Commission
The authors acknowledge the financial support of European Commission (FP6-NANOMESO, Grant No. 016710) and thank the Swiss National Supercomputing Centre for the use of their computing facilities. We thank Erik Bitzek for the development of the grain-averaged resolved shear stress analysis tool.