Cu/Nb Nanocomposite Wires Processed by Severe Plastic Deformation for Applications in High Pulsed Magnets: Effects of the Multi-Scale Microstructure on the Mechanical Properties

Copper-based high strength and high electrical conductivity nanocomposite wires reinforced by Nb nanotubes are prepared by severe plastic deformation, applied with an Accumulative Drawing and Bundling process (ADB), for the windings of high pulsed magnets. The ADB process leads to a multi-scale Cu matrix containing up to continuous parallel Nb tubes with diameter down to few tens nanometers. After heavy strain, the Nb nanotubes exhibit a homogeneous microstructure with grain size below 100 nm. The Cu matrix presents a multi-scale microstructure with multi-modal grain size distribution from the micrometer to the nanometer range. The use of complementary characterization techniques at the microscopic and macroscopic level (in-situ tensile tests in the TEM, nanoindentation, in-situ tensile tests under high energy synchrotron beam) shed light on the interest of the multi-scale nature of the microstructure to achieve extreme mechanical properties, therefore allowing for design guidelines to further improve these properties.