45-degree rafting in Ni-based superalloys: A combined phase-field and strain gradient crystal plasticity study. (May 2020)

• Record Type: Journal Article
• Authors: Ali, Muhammad Adil; Amin, Waseem; Shchyglo, Oleg; Steinbach, Ingo
• Is Part Of: International journal of plasticity. Volume 128(2020:May)
• Publication Date: 2020-05
• Subjects: Superalloys -- Dislocations -- Rafting -- Directional coarsening -- Phase field -- Crystal plasticity; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2020.102659
• Languages: English
• ISSNs: 0749-6419

Abstract

Abstract: 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- and 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. Graphical abstract: Highlights: Strain gradient crystal plasticity model is coupled with the phase-field framework. 3D creep simulations are performed in the high temperature, low stress regime. High stresses (>600 MPa) lead to so-called mixed mode rafting. Localized creep strain (¿10%) favors 45 ° rafting.