Lattice Distortion in Nano-structured Composites

1. 0.0025 mm 1.0 mm Scanning Electron Microscope images, showing the hierarchical structure of the Copper-Niobium nano-structured composite, from the full image of the Cu–Nb conductor (left) to the nano-structure inside a single fiber (right). Lattice Distortion in Nano-structured Composites Copper (Cu), Niobium (Nb) and Silver (Ag) metals all have cubic crystallographic structure. The deformation of Cu-Ag or Cu-Nb composites produces nanostructure, i.e. very fine structure between the pure-Cu and pure-Nb regions of the composite (below). These nano-composites have enormous strength – strength that greatly exceeds that of both copper and niobium. A collaboration at the National High Magnetic Field Laboratory measures another result of the co-deformation: the development of short periodicity internal strains (right), such that both of the component metals are distorted from cubic crystallographic structure. The lattice distortions are anisotropic, i.e. different in different orientations. Cyclically stretching or thermally annealing the composite is very effective in removing the lattice distortions, from which it is clear that nano-scale two-phase structure is the primary reason for the strengthening observed in nano-composites Lattice distortion resulting from deformation of a nano-composite. The different strains in the copper and niobium influence both mechanical and transport properties of the nano-composite. K. Han, A.C. Lawson, J.T. Wood, J.D. Embury, R.B. von Dreele and J.W. Richardson, Jr., Philosophical MagazineA84, 2579 (2004)