ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

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Phase-field coupled strain gradient crystal plasticity model to study high temperature creep in Ni-based superalloys

Date: 15.06.2021
Time: 02:30 p.m.
Place: 15th International Conference on Creep and Fracture of Engineering Materials and Structures

Muhammad Ali
Oleg Shchyglo
Ingo Steinbach

Creep resistance of superalloys at high temperature is one of the most important parameters defining the range of applicability of superalloys. A combination of thermodynamics and material diffusion with elasto-plasticity within the framework of phase-field allows us a depth and systematic analysis of creep behavior of superalloys. In order to investigate the creep properties of single crystal Ni-based superalloys during the evolution of microstructure, a dislocation-based strain gradient crystal plasticity model [1] is implemented. The model is calibrated against the experimental results of a creep test at a high temperature and low stress. Then, it is used to predict the kinetics of the microstructure up to 1% creep strain, in which diffusion is assumed to be controlled by the slowest diffusing element Rhenium Re [2]. It is demonstrated that the loss of coherency between the matrix and the precipitate is crucial for the coalescence of the γ precipitate and initiation of rafting [3,4,5] and rotation of the γ matrix. It is further observed that highly localized shear bands were formed under high stresses and a tendency of rafting direction toward 45 degrees [6]. Finally, sensitivity of microstructural topology and evolution kinetics towards creep properties of superalloys was analyzed [4,5]. The effect of pre-strained matrix on the evolution of γ precipitates is highlighted.

[1] P. Engels, A. Ma, Alexander Hartmaier, Continuum simulation of the evolution of dislocation densities during nanoindentation, International Journal of Plasticity journal, 38 (2012) 159–169.
[2] B. Ruttert, O. Horst, I. Lopez-Galilea, D. Langenka, A. Kostka, C. Somsen, J.V. Goerler, M.A. Ali, O. Shchyglo, I. Steinbach, G. Eggeler, and W. Theisen, Rejuvenation of Single-Crystal Ni-Base Superalloy Turbine Blades: Unlimited Service Life? Metallurgical and Materials Transactions A, 49A (2018), pp. 1-12.
[3] J. V. Goerler, I. Lopez-Galilea, L. Mujica Roncery, O. Shchyglo, W. Theisen, I. Steinbach, Topological phase inversion after long-term thermal exposure of nickel-base superalloys: Experiment and phase-field simulation, Acta Materialia, 124 (2017) pp. 151-158.
[4] C. Wang, M. A. Ali, S. Gao, J.V. Goerler, I. Steinbach, Combined phase-field crystal plasticity simulation of P- and N-type rafting in Co-based superalloys, Acta Materialia 175 (2019) 21-34.
[5] M. A. Ali, I. Lopez-Galilea, W. Amin, S. Gao et al. Effect of γ′ precipitate size on hardness and creep properties of Ni-base single crystal superalloys: experiment and simulation, Materialia, 12, 100692, (2020).
[6] M. A. Ali, W. Amin, O. Shchyglo, I. Steinbach. 45-degree rafting in Ni-based superalloys: a combined phase-field and strain gradient crystal plasticity study, International Journal of Plasticity, 128, 102659, (2020).

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