The improvement of high temperature oxidation of Ti–50Al by sputtering Al film and subsequent interdiffusion treatment

• Published in: Acta materialia Vol. 51; no. 11; pp. 3109 - 3120
• Main Authors: Chu, M.S., Wu, S.K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 27.06.2003; Elsevier Science
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cyclic oxidation; Exact sciences and technology; Interdiffusion treatment; Metals. Metallurgy; Other nonelectronic physical properties; Physical properties of thin films, nonelectronic; Physics; Sputtering Al thin film; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); TiAl 3 and TiAl 2 phases; Ti–50Al intermetallics; Cyclic oxidation; Sputtering Al thin film; Ti–50Al intermetallics; TiAl 3 and TiAl 2 phases; Interdiffusion treatment; Scanning electron microscopy; Intermetallic compounds; Interdiffusion; Ti-50Al intermetallics; XRD; TiAl3 and TiAl2 phases; Experimental study; Titanium base alloys; Sputtering; Binary alloys; Aluminium alloys; Oxidation
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/S1359-6454(03)00123-X

The high temperature oxidation resistance of Ti–50Al can be improved by sputtering an Al film and subsequent interdiffusion treatment at 600 °C for 24 h in high vacuum. In these conditions, a TiAl 3 layer is formed on the surface, which exhibits good adhesion with Ti–50Al substrate and provides high oxidation resistance. Cyclic and isothermal oxidation tests show that the Ti–50Al with 3–5 μm Al film can dramatically reduce the oxidation at 900 °C in air, at which the parabolic oxidation rate constant K p of specimen with 5 μm Al film is only about 1/15,000 of that of bare Ti–50Al. XRD and SEM results indicate that the TiAl 3 layer can promote the formation of a protective Al 2O 3 scale on the surface as well as react with γ-TiAl to form TiAl 2 during the oxidation. Simultaneously, layers of Al 2O 3/TiAl 2/Al-enriched γ-TiAl/Ti–50Al are also formed on specimens. The TiAl 2 layer thickness will decrease gradually with increasing the oxidation time. After oxidation at 900 °C for 300 h, there is a clearly discontinuous thin layer of Ti 37Al 53O 10 compound observed in between Al 2O 3 and TiAl 2.