ATOMIC-FORCE MICROSCOPY OF SLIP LINES ON THE SURFACE OF A FATIGUED NICKEL SINGLE-CRYSTAL

Atomic force microscopy (AFM) was used to determine the width and the height of slip steps which emerged at the polished surface of a cyclic ally strained nickel crystal due to strain localization in slip bands (SBs), after a deformation of one half-cycle in tension. In addition t o the AFM measurements the dislocation arrangements beneath the specim en surface were imaged with scanning electron microscopy (SEM), applyi ng the electron channelling contrast technique. The evaluation of the AFM and SEM measurements made it possible to determine the volume frac tion of slip bands and the spectrum of resolved shear strains in the S Bs for the imposed shear strain amplitude. The results are discussed w ithin the framework of the 'two-phase' model of Winter.