Change of internal strains in ultrafine-grained nickel due to cyclic plastic deformation

Ultra-fine grained nickel samples were cyclically deformed at room temperature and at 200°C. The mean grain size of about 200 nm, determined by SEM and from the broadening of synchrotron diffraction profiles remained nearly constant, whereas the spectrunm of internal strains changed in consequence of the cyclic deformation. The relation between the profile shape ans asymmetry and the {hkl} reflection type suggests the existence of long range granular stresses in the original ufg samples.