Oxygen-free high conducting copper wires drawn to true strains of 2.3, 3.1, and 3.6 exhibit inhomogeneity in the form of three distinct concentric regimes: the inner core, the midsection, and the outer region. While the microtexture of the inner core was dominated by a strong <111> + weak <100> duplex fiber texture, the midsection and the outer region had a comparatively weaker texture. An upper bound plasticity modeling and the nanohardness measurement revealed that the midsection was the most strained region. Upon annealing at 170 °C, the 2.3-strained wire did not recrystallize, whereas the 3.1- and 3.6-strained wires exhibited partial recrystallization. For the 3.6 wire, the inner core was unrecrystallized, while the midsection and outer region recrystallized with strong <100> + weak <111> fiber texture. The recrystallized grains were classified as type “A” grains, which grew laterally with <100>//DD orientation, and type “B” grains, which generally grew axially with <111>//DD orientation.

The national high magnetic field laboratory builds and uses various highfield magnets for fundamental research. In building high field magnets, avariety of high strength composites are required because of the Lorentzstresses generated by high field exceeding the strength of most of thematerials, particular conductors. For example, a field of 60 T can generatea magnetic pressure that corresponds to a stress in the conductor of 1.5GPa, which is at the limit of known conducting materials with conductivityhigher than 70% International Annealed Copper Standard and sizes suitablefor building high field magnets. The design of high field magnets is limitedby these forces and, consequently, by the available materials. At the sametime, the materials need to have excellent physical properties. Forinstance, the conductors need to have high electrical conductivity and highspecific heat and the superconductors should have high critical current infield and low alternative current losses. This paper outlines ourrequirements and research on metal matrix composite materials for buildinghigh field magnets. The discussions include both the macrocomposite andmicrocomposite. The scales of the structures in the composites are frommillimeters to nanometers.