Background: Nickel-based superalloys are usually exposed to high static or cyclic loads in
non-ambient environment, so a reliable prediction of their mechanical properties, especially
plastic deformation, at elevated temperature is essential for improved damage-tolerance
assessment of components.
Methods: In this paper, plastic deformation in a single-crystal nickel-based superalloy CMSX4
at elevated temperature was modelled using discrete dislocation dynamics (DDD). The DDD
approach was implemented using a representative volume element with explicitly-introduced
precipitate and periodic boundary condition. The DDD model was calibrated using stress-strain
response predicted by a crystal plasticity model, validated against tensile and cyclic tests at 850°C
for and crystallographic orientations, at a strain rate of 1/s. Results: The DDD model was capable to capture the global stress-strain response of the
material under both monotonic and cyclic loading conditions. Considerably higher dislocation
density was obtained for the orientation, indicating more plastic deformation and much
lower flow stress in the material, when compared to that for orientation. Dislocation lines
looped around the precipitate, and most dislocations were deposited on the surface of precipitate,
forming a network of dislocation lines. Simple unloading resulted in a reduction of dislocation
density.
Conclusions: Plastic deformation in metallic materials is closely related to dynamics of
dislocations, and the DDD approach can provide a more fundamental understanding of crystal
plasticity and the evolution of heterogeneous dislocation networks, which is useful when
considering such issues as the onset of damage in the material during plastic deformation
