Oxidation subscale of γ-titanium aluminide

✍ Scribed by R. Beye; M. Verwerft; J.T.M. De Hosson; R. Gronsky

• Book ID: 104403276
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 879 KB
• Volume: 44
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(96)00032-8

✦ Synopsis

The subscale formed during high temperature rapid oxidation of ;'-titanium aluminum is revealed by transmission electron microscopy and microanalysis to consist of two phases: one hexagonal with unit cell dimensions a = 0.58nm, c = 0.47rim (+ 0.005nm), and a composition close to Ti~AhO4" the other simple cubic with a = 0.69nm (+ 0.005nm) and composition Ti3AI.,O~, with oxygen concentration known to about 10% accuracy. The results strongly suggest that the hexagonal phase is a solid solution of O in Ti3AI, while the cubic phase is a novel ternary compound with space group P4.,32. These subscale phases exhibit some tendency for a crystallographic orientation relationship with (1 lO).ub,.//(OlTO)he~o~ and [0Tl].ub,c//[' 5112]ho~.~o..~, and the hexagonal phase is less stable than the cubic phase as the distance to the sample surface decreases and oxygen level increases.