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3D Discrete Dislocation Dynamics Applied to Interactions between Dislocation Walls and Particles

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Záležák T., Dlouhý A.

Acta Physica Polonica A

2012

vol. 122

issue 3

450-452

A 3D discrete dislocation dynamics model is presented that describes dislocation processes in crystals subjected to mechanical loadings at high temperatures. Smooth and curved dislocations are approximated by a set of short straight line segments. A Peach-Koehler force acting upon each segment involves all segment-to-segment interactions and externally applied stress. The segment velocity is a product of a corresponding mobility and the glide or climb component of the Peach-Koehler force. The model addresses interactions between dislocations and rigid spherical precipitates. A migration of low angle tilt boundaries situated in a field of precipitates is simulated as an example. The numerical implementation exploits symmetries of the model that yield an optimized and highly efficient numerical code. Results provide detailed insight into how dislocation arrangements surmount particle fields in 3D crystals.

3D Discrete Dislocation Dynamics: Influence of Segment Mobility on Critical Shear Stress

100%

Záležák T., Dlouhý A.

Acta Physica Polonica A

2015

vol. 128

issue 4

654-656

We use 3D discrete dislocation dynamics technique to study a low-angle tilt boundary migration subjected to applied shear stress at high temperatures, where diffusion significantly contributes to the dislocation motion. The model considers Peach-Koehler forces due to interactions between individual straight dislocation segments. The model also addresses dislocation plasticity in a field of impenetrable incoherent spherical precipitates. Velocities of the individual dislocation segments are calculated in relation to the crystallography of the material. Several calculation series have been carried out for different velocity and driving force relations. The results show that there exists a critical applied shear stress, below which the low angle dislocation boundary cannot surpass the rigid precipitates and remains in an equilibrium configuration. This agrees with experimental results obtained in creep tests of dispersion strengthened alloys. The critical stresses have been calculated also for situations where the applied stress was decreased during the interaction between the low-angle tilt boundary and the precipitates.

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2 Acta Physica Polonica A

1 2015

1 2012

2 Dlouhý A.

2 Záležák T.

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3D Discrete Dislocation Dynamics Applied to Interactions between Dislocation Walls and Particles

3D Discrete Dislocation Dynamics: Influence of Segment Mobility on Critical Shear Stress