Microstructural analysis and corrosion behavior of zirconium-stainless steel metallic waste form

Management of radioactive metallic waste using “alloy melting route” is currently being investigated by several researchers. In the present study, potentiodynamic polarizations were conducted on six as-cast zirconium (Zr)-stainless steel (SS) alloys (i.e. Zr-25, 20, 16, 12, 8 and 5 wt.% SS) at pH = 1, 5 and 8. Electrochemical behavior of metallic-waste-form (MWF) alloys containing more than 16 wt.% SS showed lower potentials at the break down of passivity attributed to localized attack mainly at Cr-depleted matrix–intermetallic interfaces. Zr–5SS and Zr–12SS alloys contain Zr3(Fe, Cr, Ni)/Zr3(Fe, Cr)-type of phases and their interfaces with matrices were prone to localized attack. Whereas, Zr–8SS and Zr–16SS alloys demonstrated better corrosion resistance in comparison to Zr–5SS and Zr–12SS respectively. In addition, occurrence of Laves phase, e.g. Zr2(Fe, Cr), in Zr–8SS and Zr–16SS alloys makes them suitable for MWF.