Comparing the intergranular oxidation of Ni-Cr and Ni-Al model alloys in 480 °C hydrogenated steam. (15th July 2023)

• Record Type: Journal Article
• Authors: Ghaffari, Y.; Daub, K.; Long, F.; Topping, M.; Persaud, S.Y.
• Is Part Of: Scripta materialia. Number 232(2023)
• Publication Date: 2023-07-15
• Subjects: Ni-Cr -- Ni-Al -- Internal oxidation -- Intergranular oxidation -- Grain boundary misorientation; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2023.115501
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: The intergranular oxidation of binary Ni-xAl ( x = 4, 7 at.%) and Ni-yCr ( y = 11, 15 at.%) model alloys was studied in a 480 °C hydrogenated steam environment. It was observed that the intergranular oxidation susceptibility in Ni-Al and Ni-Cr alloys is different. In Ni-Al alloys, HAGBs are very susceptible to intergranular oxidation, while low energy grain boundaries behave similar to bulk material. In Ni-Cr alloys, LAGBs and CSLBs are susceptible to intergranular oxidation, while HAGBs are protected by an external oxide. The structure of the intergranular oxide was also different between Ni-Cr and Ni-Al alloys; the intergranular oxide formed in Ni-Al alloys was sharper and penetrated to greater depth compared with Ni- Cr alloys. Comparisons are made to previous testing of alloy 600 (Ni-16Cr-Fe) in similar environments, highlighting the potential effect of residual Al and Ti on the intergranular oxidation of the alloy. Graphical abstract: Image, graphical abstract