Porosity-related high-cycle fatigue strength of nickel-base single crystals: fatigue experiments and Electron Back-scattered Diffraction analysis

The fatigue limit of nickel-base single crystal (NBSX) is experimentally studied at an elevated temperature of 980°C. The crack initiation position is revealed as the casting pores in the single crystal under scanning electron microscope (SEM), and distinct “fish-eye” region is observed on the long cycle fatigue fracture surface. The failure mechanism is explored around the “fish-eye” by adopting the focused ion beam (FIB) and electron backscatter diffraction (EBSD) technique. The crystalline motion and the fatigue crack initiation mechanism around the initiation pore are revealed by conducting microscopic analyses.