Corrosion Behavior of Zr-1.0Fe-0.2Cu Alloy in 400℃/10.3 MPa Steam

High purity zirconium was used as the base material to fabricate Zr-1.0Fe-0.2Cu alloy. The microstructure and corrosion behavior in 400℃/10.3 MPa superheated steam of this alloy were investigated using SEM and TEM. The results show that the Zr3Fe phase with orthogonal center structure is the typical second phase in the Zr-1.0Fe-0.2Cu alloy. Cu is prone to segregate to the Zr3Fe phase, rather than to form Zr2Cu phase. The addition of Cu element can refine the Zr3Fe phase in the alloy. When the Zr-1.0Fe-0.2Cu alloy was exposed to the superheated steam for 100 d, its corrosion resistance is better than that of Zr-1.0Fe alloy and Zr-4 remelting alloy, which indicates that adding a small amount of Cu element is beneficial. In the oxidation process, Cu-containing Zr3Fe phase is oxidized behind the α-Zr matrix and thus surrounded by the oxide film. As the oxidation progresses, Zr in the second phase is oxidized into tetragonal zirconia. Fe is oxidized into Fe3O4 phase with monoclinic structure. Furthermore, the original aggregation state of Cu and Fe in the Zr3Fe phase has disappeared due to the diffusion and oxidation in the oxide film of these elements. © 2020, Science Press. All right reserved.