Oxidation of typical Zr-1 Nb alloy in high-temperature air under 700–900 °C. (December 2022)

• Record Type: Journal Article
• Authors: Jiang, Guanyu; Xu, Donghai; Liu, Lu; Ding, Xin; Kuang, Wenjun; Wang, Mingjun
• Is Part Of: Corrosion science. Volume 209(2022)
• Publication Date: 2022-12
• Subjects: M5 alloy -- Oxidation -- Air -- Kinetics acceleration; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110701
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: In order to promote the understanding of Zirconium alloy cladding failure under loss of coolant accidents (LOCA), air oxidation behavior of Zr-1 Nb-0.12 O (M5) alloy at 700–900 °C for 1–2 h was investigated. At different temperatures and times, m-ZrO2 was always the dominant phase of surface oxides, whereas oxide shapes, the integrity and roughness of oxide films differed noticeably. At 900 °C, M5 alloy exhibited accelerated kinetics and breakaway oxidation after approximately 80 min air exposure. The presence of ZrO and ZrO0.35 sub-oxides accounts for the high reaction activation energy (149.6 kJ/mol). During the kinetics acceleration, some intergranular cracks turned transgranular. The oxide/metal (O/M) interface became wavy, massive long transverse cracks and small radial cracks appeared in the oxide film, and pores distributed on the oxide layer and O/M interface. Air ingress through the oxide layer to initiate the matrix oxidation is jointly affected by air transport and ion diffusion. Highlights: Oxidation of M5 alloy in high-temperature air was studied. Multiple characterization techniques were employed. Kinetics acceleration and breakaway oxidation were clarified. Influences of air and other relevant parameters were discussed.