This work examines the evolution of the dislocation structure in large grains of polycrystalline copper with decreasing strain amplitude. The experimental results show that (1) dislocation reversal was initially triggered by the operation of a final slip system, which was formed by the previously high strain amplitude when the strain amplitude was reduced; and (2) the region that was occupied by the dislocation reversal structures called loop patches. It was small in large grains because a more homogenous internal stress distribution induces a more uniform evolution of dislocations in large grains.

Evolution of Dislocations in Large Grains of Polycrystalline Copper under Low Cycle Fatigue with Reduced Strain Amplitude. S.W.Mao, C.W.Chang, H.L.Huang, N.J.Ho: Materials Science and Engineering A, 2010, 527[24-25], 6489-93