Understanding the growth mechanisms of TiO2/Al2O3 mixed scales formed on Al-depleted Ti2AlC at 1000–1200 °C. (1st August 2022)

• Record Type: Journal Article
• Authors: Liu, Xuanzhen; Chen, Ying; Li, Ling; Zhang, Han; Huang, Aihui; Fan, Xiaohui; Zhao, Xiaofeng; Lu, Jie
• Is Part Of: Corrosion science. Volume 204(2022)
• Publication Date: 2022-08-01
• Subjects: Ti2AlC -- Oxidation -- Microstructure evolution -- Mixed oxide scales; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110393
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: We present a detailed study of thermally grown oxide scales on a bulk Ti2 AlC material and explore its oxide growth mechanisms at 1000 °C, 1100 °C and 1200 °C, respectively. The oxide scale predominantly consists of an outer TiO2 -rich layer and an inner TiO2 /Al2 O3 mixed layer. The formation of such a duplex microstructure is caused by the phase transformation from Ti2 AlC to TiC at the scale/substrate interface and the Al depletion due to the formation of impurities. The insufficient supply of Al to scale/substrate interface, together with the competition from growth of TiO2, prevents formation of a continuous Al2 O3 scale. Highlights: A thick TiO2 /Al2 O3 mixed scale (500–1000 µm) forms on Ti2 AlC at 1000–1200 °C. The Al content has been significantly decreased in the Ti2 AlC matrix due to the formation of TiAl3 and Al2 O3 impurities. The fast outward diffusion of Al leads to the decomposition of Ti2 Alx C into TiC, thus forming porous structures. The insufficient supply of Al to the scale/substrate interface and high oxygen pressure makes it preferential to establish a TiO2 /Al2 O3 mixed scale.