Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C. (13th April 2018)

• Record Type: Journal Article
• Authors: Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon
• Is Part Of: Materials research express. Volume 5:Number 4(2018)
• Publication Date: 2018-04-13
• Subjects: Al/Cr coating -- Ti2AlNb alloy -- oxidation behavior -- magnetron sputtering -- double glow -- diffusion; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/aabab1
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: In this paper, the Al/Cr coating was fabricated on the surface of Ti2 AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2 AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2 AlNb alloy with prolonged air exposure at 900 °C. Al2 O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2 AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2 O3 . Besides, Cr2 O3 was produced under Al2 O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2 AlNb alloy increases oxidation resistance.