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Abstract

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.

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