Competitive role of primary ?' precipitates and annealing twins on the heterogeneous deformation of a polycrystalline ni-based superalloy: Crystal plasticity modeling and experiments

A crystal plasticity modeling framework is developed and used in combination with experiments for studying the deformation behavior of a polycrystalline Ni-based superalloy. In particular, the monotonic stress-strain response across a range of temperatures and the misorientation development at room temperature are predicted. The model accounts for individual deformation of the matrix and primary & gamma;& PRIME; phases, with consideration for the various strengthening mechanisms observed in these alloys. The as-received microstructure has been characterized using Energy Dispersive X-Ray Spectroscopy (EDS) and the concentration of the solute atoms present in the & gamma; and primary & gamma;& PRIME; phases obtained from these measurements are used to inform the solute solution strengthening model. Further, the Electron Back Scatter Diffraction (EBSD) microstructures are directly used as inputs for the simulations. The model is first calibrated to the experimental stress-strain response at 293 K and 923 K and then validated by predicting the mechanical response at 523 K and 723 K. Interrupted tensile testing has been performed using a combination of Scanning Electron Microscopy (SEM) and EBSD to study the misorientation developments during deformation. These deformed microstructures are correlated with the simulated EBSD microstructures, in terms of the competitive misorientation developments at grain boundaries, annealing twin boundaries and phase interfaces. Higher misorientation developments were observed at the twin boundaries as compared to the grain boundaries and phase interfaces, indicating a higher propensity of heterogeneous deformation.