Effect of diffusive Nb redistribution on the pitting susceptibility of U-5.5Nb alloys

Abstract The influence of diffusive Nb redistribution on the microstructure and Volta potential of U-5.5Nb alloys thermally aged at 400 °C for durations between 1 h and 100 h was investigated and their surfaces were examined post-corrosion using various microscopy techniques. The results demonstrated that Nb-depleted lamellae resulting from Nb redistribution have the lowest Volta potential in the microstructure and are extremely sensitive to pitting, as demonstrated by immersion experiments and potentiometric polarization tests. However, the pitting potential of the aged alloys (205.2 ± 3.9 mV) did not change with the content of Nb-depleted lamellae.