Establishing effective criteria to link atomic and macro-scale simulations of dislocation nucleation in FCC metals

Burbery, N, Das, R, Ferguson, W, Po, G and Ghoniem, N 2015, 'Establishing effective criteria to link atomic and macro-scale simulations of dislocation nucleation in FCC metals', in G. R. Liu and Raj Das (ed.) Proceedings of the 6th International Conference on Computational Methods (ICCM 2015), Auckland, New Zealand, 14-17 July 2015, pp. 62-73.


Document type: Conference Paper
Collection: Conference Papers

Title Establishing effective criteria to link atomic and macro-scale simulations of dislocation nucleation in FCC metals
Author(s) Burbery, N
Das, R
Ferguson, W
Po, G
Ghoniem, N
Year 2015
Conference name ICCM 2015
Conference location Auckland, New Zealand
Conference dates 14-17 July 2015
Proceedings title Proceedings of the 6th International Conference on Computational Methods (ICCM 2015)
Editor(s) G. R. Liu and Raj Das
Publisher Scientech
Place of publication United States
Start page 62
End page 73
Total pages 12
Abstract Processes at fundamental length scales contribute collectively, in a statistical manner, to the macro-scale effects observed at length scales several orders of magnitude higher. To derive useful quantities pertaining to real material properties from atomic scale simulations, it is critical to evaluate the cumulative effect of multiple atomic- scale defects at the 'meso'- and 'micro'- scales. This study aims to develop a phenomenological model for atomic scale effects, which is a critical step towards the development of a comprehensive meso-scale simulation framework. In moderate loading conditions, dislocations in FCC metals are dictated by thermally activated processes that become energetically favourable as the stress approaches a threshold value. The nudged elastic band technique is ideal for evaluating the energetic activation parameters from atomic simulations, in order to evaluate the stress, temperature and rate dependence of a process. On this basis, a constitutive mathematical model is developed for simulations at the meso-scale with respect to the atomic activation parameters, to evaluate the critical (local) shear stress threshold. Once models are established for multiple effects, such as dislocation junction formation, cross-slip, and nucleation, the threshold temperature and stress for a transition between different effects can be evaluated. For example, the threshold temperature can be evaluated during heating, beyond which an immobilised dislocation in a junction will be activated for cross-slip and will shift into an adjacent mobile slip system. This is useful to predict the rate-limiting dislocation process at each simulation timestep, by evaluating the simulation condition-dependent criteria.
Subjects Materials Engineering not elsewhere classified
Keyword(s) Multi-scale computer simulations
dislocation dynamics
FCC metals
polycrystalline plasticity
activation parameters
Copyright notice © 2015 This work is licensed under a Creative Commons Attribution 3.0 License.
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