The dislocation structures evolution on the polycrystalline Cu at constant strain amplitude during low-cycle fatigue was well understood. However, the dislocation structures developments at variable strains, which changed from high to low strain amplitude, were seldom reported. In order to realize the dislocation morphology evolution at reduced strain amplitude, the polycrystalline Cu was used here. The results showed that: (a) The S–N curve at reduced strain amplitude from high to low revealed softening, and it was lower than S–N curve which was fatigue in constant strain amplitude at low strain amplitude, (b) The dislocation structures of walls, labyrinth walls, cells or misorientation cells transfer into scattering walls, loop patches or cells, (c) The dislocation morphology

development at decreased strain amplitude was determined by the magnitude of reduction in strain amplitude.

A Study of Dislocation Evolution in Polycrystalline Copper during Low Cycle Fatigue at Low Strain Amplitudes. H.L.Huang: Materials Science and Engineering A, 2003, 342[1-2], 38-43