Materials Research Bulletin, Vol.80, 295-302, 2016
Development in corrosion resistance by microstructural refinement in Zr-16 SS 304 alloy using suction casting technique
Zirconium (Zr)-stainless steel (SS) hybrid alloys are being considered as baseline alloys for developing metallic-waste-form (MWF) with the motivation of disposing of Zr and SS base nuclear metallic wastes. Zr-16 wt.% SS, a MWF alloy optimized from previous studies, exhibit significant grain refinement and changes in phase assemblages (soft phase: Zr-2(Fe, Cr)/alpha-Zr vs. hard phase: Zr-3(Fe, Ni)) when prepared by suction casting (SC) technique in comparison to arc-cast-melt (AMC) route. Variation in Cr-distribution among different phases are found to be low in suction cast alloy, which along with grain refinement restricted Cr-depletion at the Zr-2(Fe, Cr)/Zr interfaces, prone to localized attack. Hence, SC alloy, compared to AMC alloy, showed lower current density, higher potential at the breakdown of passivity and higher corrosion potential during polarization experiments (carried out under possible geological repository environments, viz., pH 8, 5 and 1) indicating its superior corrosion resistance. (C) 2016 Elsevier Ltd. All rights reserved.
Keywords:Intermetallic compounds;Microstructure;Electron microscopy;X-ray diffraction;Electrochemical properties