High Strength, High Conductivity Microcomposite Cu-Nb Wires with Cross Sections in the Range of 0.01–100 ${\hbox{mm}}^{2}$

Abstract

Effect of anomalous increase of strength in fine heavily deformed Cu-Nb microcomposites is associated with nano-scaled microstructure. For these wires with cross sections in the range of 0.01-0.5 mm2 the high level of ultimate tensile strength (UTS) can be attained by straight deformation of initial in situ composite Cu-Nb ingot with logarithmic strain up to 11. For fabrication of high strength Cu-Nb wires with much larger cross sections up to 100 mm2 the ldquobundle-and-deformrdquo method should be used. In this case the final wire consists of bulk soft copper matrix with embedded high strength Cu-Nb microcomposite cores. The design features of high strength high conductivity Cu-Nb winding wires with extremely wide range of cross sections have been analyzed. Some peculiar features of deformation of non-uniform composites containing the nanostructured elements have been presented. Mechanical properties and conductivity of these wires have been reviewed. It was shown that UTS values from 900 MPa up to 1500 MPa and conductivity values in the wide range from 55% IACS to 85% IACS could be attained for Cu-Nb wires with different designs. The analysis has been done on the correlation of the mechanical and conducting properties with microstructure.