Microstructure in Cu–Nb microcomposites

Abstract

Two types of Cu–Nb microcomposites were studied by transmission electron microscopy. The in-situ composites were prepared by casting, followed by deformation, packing and deformation. The composites were formed by self-assembling and show strong textures and orientation relationship between Cu and Nb. The artificial composites were made by cladding Nb with Cu, packing and deformation, and they developed less pronounced texture than in-situ composites. In spite of the differences in the original orientation relationship and microstructure, the final products of both composite show the {1 1 1} Cu//{1 1 0} Nb orientation relationship and fiber textures. Moreover, both types of composites are composed of Nb ribbons or plates embedded in the copper matrix. A variation in the spacing between the Nb ribbons is observed, particularly in the in-situ composites. In Cu regions, very fine twins have been revealed. Various strain contrasts were observed in the interface regions and the lattice distortion occurred in both components. The high strength of the microcomposite is attributed to large interface areas in the unit volume, lattice distortions and the nanostructures. Those strength contributors are related to each other.