3D DDD modelling of dislocation-precipitate interaction in a nickel-based single crystal superalloy under cyclic deformation
journal contributionposted on 19.02.2018, 14:41 by B. Lin, Minsheng Huang, Liguo ZhaoLiguo Zhao, Anish RoyAnish Roy, Vadim SilberschmidtVadim Silberschmidt, N.C. Barnard, M.T. Whittaker, G. McColvin
Strain-controlled cyclic deformation of a nickel-based single crystal superalloy has been modelled by using three-dimensional (3D) discrete dislocation dynamics (DDD) for both  and  orientations. The work focused on the interaction between dislocations and precipitates during cyclic plastic deformation at elevated temperature, which has not been well studied yet. A representative volume element (RVE) with cubic γ’-precipitates was chosen to represent the material, with enforced periodical boundary conditions. In particular, cutting of superdislocations into precipitates was simulated by a back-force method. The global cyclic stress-strain responses were captured well by the DDD model when compared to experimental data, particularly the effects of crystallographic orientation. Dislocation evolution showed that considerably high density of dislocations was produced for  orientation when compared to  orientation. Cutting of dislocations into the precipitates had a significant effect on the plastic deformation, leading to material softening. Contour plots of in-plane shear strain proved the development of heterogeneous strain field, resulting in the formation of shear-band embryos.
The work was funded by the EPSRC (Grants EP/M000966/1 and EP/K026844/1) of the UK and in collaboration with GE Power, Dstl (Dr Matthew Lunt) and Rolls-Royce (Dr. Mark Hardy).
- Mechanical, Electrical and Manufacturing Engineering