Seminars and Events

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

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

Muhammad Adil Ali, ICAMS, Ruhr-Universität Bochum, Bochum, Oleg Shchyglo, Scale Bridging Thermodynamic and Kinetic Simulation, Ruhr-Universität Bochum, Bochum, Ingo Steinbach, Ruhr-Universität Bochum, Bochum

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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