Observations of Dislocations in Cu/Nb Nanolayer Composites After Deformation

Dislocations have been observed in deformed Cu/Nb nanolayer composites of wavelength 17 and 7 nm. The dislocations thread through the Cu/Nb interfaces even though there is a change of Burgers vector. Conventional and high resolution transmission electron microscopy studies show that the in-plane bowing direction of these dislocations in the Cu layers is opposite to that in the Nb layers, so that the dislocations appear to zig-zag. These observations are explained by the presence of residual tensile stresses in Cu and residual compressive stresses in Nb, which make dislocations bow in opposite directions in the alternating layers.