CORROSION BEHAVIOR OF Zr(Fex, Cr1-x)2 ALLOYS IN 400 °C SUPERHEATED STEAM

To study the corrosion behavior of second phase particles in zirconium alloys, Zr(Fe-x, Cr1-x)(2) (x = 1, 2/3, 1/3) metallic compounds which have the same composition as the second phase particles in Zr-4 alloy were prepared by vacuum non-consumable arc melting. XRD and energy filtered TEM were employed for analyzing the corrosion products, the element distribution and grain morphology after corrosion tests of Zr(Fe-x, Cr1-x)(2) metallic compounds powder at 400 degrees C and 10.3 MPa superheated steam with different exposure times. The results show that Cr has a very strong effect on the corrosion resistance of Zr(Fe-x, Cr1-x)(2) metallic compounds, increasing Cr content can improve the corrosion resistance. When Zr(Fe-x, Cr1-x)(2) oxidation starts, zirconium oxide is formed while elements Fe and Cr are expelled from the zirconium oxide due to their low solid solubility in the oxide. alpha-Fe(Cr) and gamma-Fe(Cr) are formed and then oxidized to the stable corrosion product (Fe, Cr)(3)O-4. The different corrosion behaviors of metallic compounds will affect the microstructure evolution of zirconium oxide layer differently during the corrosion process, and hence affect the corrosion resistance of zirconium alloys.