Cold rolling reduces the dislocation densities in Ni–18%Fe alloys prepared by electrochemical deposition. The dislocation density evolution previously proposed for the linearly decreasing work-hardening rate during stage III was revisited. The solution of the differential equation predicts that when the initial dislocation density was smaller or larger than the saturation value, then the dislocation density will increase or decrease during further plastic deformation. The predictions were verified by experimental values of dislocation densities determined by X-ray line-profile analysis.

Work Softening in Nanocrystalline Materials Induced by Dislocation Annihilation. T.Ungár, L.Li, G.Tichy, W.Pantleon, H.Choo, P.K.Liaw: Scripta Materialia, 2011, 64[9], 876-9