Deformation-enhanced diffusion in single-crystalline Ni-based superalloy specimens have been investigated under the conditions of hard cyclic viscoplastic tension-compression deformation. The chemical composition of phases before and after cyclic deformation was investigated by filed-emission scanning electron microscopy. At low strain amplitude values (0-0.05%; 0-0.2%; 0-0.5%) the material shows upscaled viscoelastic behavior and microstructural stability. At the increase of strain amplitude in the γ+γ’-phase (0-1%), the Ni, Re and Co content decreases, whereas Al and Mo content increases significantly. On the contrary, in the single γ’-phase area, the Ni and Co content was increased, which was accompanied by a decrease of Nb, Cr, Ta and Al content. The length of dendrite arms was significantly decreased as compared to primary dendrite arms and γ+γ’-rafts were formed parallel to the stress axis direction. As a result of the deformation-enhanced, diffusion the necking of dendrites accompanied with longitudinal cracking by the dendrite axis and cross-sectional radial cracking by interdendritic region of single crystalline specimen occurs.