Evolution of the Structure and Properties of Cu–6% Nb Microcomposite Wire during Long-Term Temperature Tests

Abstract

The electrical conductivity, mechanical strength and crystal structure of Cu–6 wt % Nb microcomposite wire upon exposure to a temperature of 450°C for up to 2000 hours are investigated. Structural changes are compared with the ultimate strength and electrical conductivity. Several mechanisms of strength degradation with different time constants are identified. Within long times, the ultimate strength decreases by 32% from the initial value while the electrical conductivity increases by no more than 2%. Strength degradation is accompanied by the relaxation of microstresses in the copper matrix and structural changes in the nanoscale niobium component.