Journal
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
Volume 24, Issue 8, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0965-0393/24/8/085017
Keywords
stacking fault energy; molecular dynamics simulation; semi-empirical potentials
Funding
- Department of Energy, Office of Basic Energy Sciences [DE-AC02-07CH11358]
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Dislocation nucleation from grain boundaries (GB) can control plastic deformation in nano-crystalline metals under certain conditions, but little is known about what controls dislocation nucleation, because when data from different materials are compared, the variations of many interacting properties tend to obscure the effects of any single property. In this study, we seek clarification by applying a unique capability of semi-empirical potentials in molecular dynamics simulations: the potentials can be modified such that all significant material properties but one, are kept constant. Using a set of potentials developed to isolate the effects of stacking fault energy, we show that for a given grain boundary, loading orientation and strain rate, the yield stress depends linearly on both the stable and unstable stacking fault energies. The coefficients of proportionality depend on the GB structure and the value of the yield stress is related to the density of the E structural units in the GB. While the impact of the stable stacking fault energy is easy to understand, the unstable stacking fault energy requires more elucidation and we provide a framework for understanding how it affects the nucleation and propagation process.
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