Study on Corrosion Resistance of Zr-Sn-Nb-Fe Zirconium Alloys

The corrosion resistance of stress relieved and recrystallized SZA-4（Zr-0.8 Sn-0.25 Nb-0.35 Fe-0.1 Cr-0.05 Ge） and SZA-6（Zr-0.5 Sn-0.5 Nb-0.3 Fe-0.015 Si） alloys, and stress relieved reference alloy A（Zr-1 Sn-1 Nb-0.1 Fe） are studied by static autoclaves in three different water conditions: 360℃/18.6 MPa deionized water, 360℃/18.6 MPa/0.01 mol·L^-1 lithiated water and 400 ℃/10.3 MPa superheated steam. SEM and TEM are used to analyze the microstructures. The results showed that the corrosion resistance of SZA-4 and SZA-6 are both better than that of alloy A in all the water conditions. The corrosion resistance of recrystallized SZA-4 is better than that of stress relieved SZA-4, while SZA-6 shows the reverse phenomenon. There are two kinds of SPPs in SZA-4, one is Zr（NbFeCr）₂ with a smaller size and the other is Zr（NbFeCrGe）₂ with a larger size, and both have a HCP structure. In SZA-6, there exists（ZrNb）₂ Fe SPPs with a FCC structure and Zr（NbFe）₂ SPPs with a HCP structure. It is concluded that the chemical compositions and the characteristics of SPPs are responsible for the difference of the corrosion resistance, and the former plays a dominant role.