The influence of the structure and composition of technically pure oxygen-free copper from various manufacturers on its electrical conductivity and mechanical properties

The composition, structure, electrical conductivity and mechanical properties of oxygen-free copper grade C10100 with a purity of 99.997% produced by Sichuan Huazi Technology Co., Ltd (China) intended for use in the production of niobium-titanium superconductors as a stabilizing component of a multi-filament composite were studied. It was shown that the recrystallization onset temperature of deformed copper samples in the form of wire is about 150 °C, and as a result of collective recrystallization at temperatures above 300 °C, the grain size reaches a value of more than 180 μm. The RRR parameter characterizing the electrical conductivity of copper at the cryogenic temperature of samples in a fully recrystallized state reaches a value of 1300 units, which is three times higher than the level typical for copper grade C10100 produced by leading manufacturers of cryogenic copper for superconductors. Maximum plasticity (up to 50%) of copper wire samples is achieved after short annealing (less than 5 minutes) at a temperature of 300°C. Increasing the annealing temperature to 600°C leads to a decrease in mechanical properties due to grain growth and the well-known effect of temperature plasticity failure.