Corrosion Resistance of Zr-1Nb-0.1Fe-xCu Alloys in Super-Heated Steam at 500℃

The corrosion resistance of Zr-0.1Nb-0.1Fe-xCu alloy in 500℃ super-heated steam was studied by static autoclave corrosion test. The second phase particles were observed by SEM and the phase composition of oxide films was analyzed by XRD respectively. The results show that the second particles in 0.1Nb-0.1Fe-xCu alloy was distributed dispersively in the grains and at the grain boundaries, and the second phase size of Cu-containing alloy was larger than that of the alloy without Cu. As the Cu content increased, the number of larger-sized second phase particles increased. Zr-0.1Nb-0.1Fe-xCu alloys with 0.05% and 0.2% Cu had better corrosion resistance than Zr-1Nb-0.1Fe alloy after corrosion in 500℃ super-heated steam for 500 h. However, the corrosion resistance of Zr-1Nb-0.1Fe-0.1Cu alloy was poorer than that of Zr-1Nb-0.1Fe alloy. Zr-0.1Nb-0.1Fe-xCu alloys with different Cu content had integrated oxide film, without obvious spalling. The oxide film was mainly composed of monoclinic m-ZrO₂.