Analysis of activated slip systems in fatigued nickel polycrystals using the EBSD-technique in the scanning electron microscope

By comparison of the observed trace angles of active slip planes with the expected traces in plastically deformed metal polycrystals, conclusions for the local stress state within the grains of polycrystalline aggregates can be drawn. The expected slip systems can be calculated when the local stress tensor and the orientation of the crystallites in the specimen space are known. In fatigued nickel polycrystals, the crystal orientation was determined by the EBSD (electron backscattering diffraction) method in the scanning electron microscope. It was shown that at the relatively small plastic strains under fatigue conditions the crystalline interactions do not essentially influence the local stress state in the grains, but the external uniaxial stress tensor remains valid in good approximation.