Lattice rotation effect on the dislocation pattern of Cu deformed in tension

摘要

The dislocation pattern of cold deformed FCC metals follows an orientation-dependent rule. However, only final orientation after deformation has been considered in related studies, i.e. without considering lattice rotation effect, although metals have undergone heavy lattice rotation during plastic deformation. In this work, the lattice rotation effect on the dislocation structures of Cu is investigated by combining electron backscatter diffraction, focused ion beam lift-out and scanning transmission electron microscopy techniques. The dislocation patterns of 110-110, 111-111 and 110-111 type grains deformed in tension under room temperature are compared. The notation h(1)k(1)l(1)-h(2)k(2)l(2) represents the lattice rotation history of a grain, meaning that the grain rotates from h(1)k(1)l(1) corner to h(2)k(2)l(2) corner during tension. It is found that for a given strain range, the dislocation cell structure is observed in 111-111 grain, while the dislocation cell block structure is dominant in 110-111 grain. This demonstrates that for Cu grains with a final orientation near 111 corner, dislocation pattern type is influenced by the lattice rotation feature. Same with 110-111 type grain, cell block structure is the main feature found in 110-110 grain, indicating that for grain with initial orientation near 110 corner, lattice rotation has a marginal effect on the dislocation structure. The relation between the dislocation structure, lattice rotation, slip system and strain level of Cu is discussed.