45-degree rafting in Ni-based superalloys: A combined phase-field and strain gradient crystal plasticity study

Ali, M.A. and Amin, W. and Shchyglo, O. and Steinbach, I.

Volume: 128 Pages:
DOI: 10.1016/j.ijplas.2020.102659
Published: 2020

45° rafting of Ni-based superalloys has been investigated with the help of creep test simulations applying a strain gradient crystal plasticity model coupled to the multi-phase field method. This mode of rafting lies in between P- A nd N-type rafting modes. The model parameters are calibrated against experimental data for N-type rafting under high temperature and low stress creep condition. By increasing the stress level, the mixed-mode rafting of precipitates with a clear tendency toward formation of 45° rafts is observed. We show that the key factor for the occurrence of this type of rafting is the generation of highly localized creep strain of more than 10% due to non-homogeneous creep deformation in the form of slip bands. We have successfully captured the evolution of microstructure under high stress leading to production of localized shear bands. © 2020 Elsevier Ltd.

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