Kim, K. S. Jee, K. K. Kim, W. C. Jang, W. Y. Han, S. H. 2024-01-20T23:05:30Z 2024-01-20T23:05:30Z 2021-09-03 2008-05-25 0921-5093 https://pubs.kist.re.kr/handle/201004/133480 Variation in oxidation behavior with heat treatment temperature is investigated for a Ni-Ti alloy using X-ray diffraction, differential scanning calorimetry and Auger spectroscopy, and the effect of oxidation on transformation behavior and superelasticity is characterized. A cold-worked Ni-49.4 at.% Ti alloy is oxidized at 300-700 degrees C for 1 h in air. With an increase in heating temperature, the structure of TiO2 changes from amorphous (300 and 400 degrees C) to anatase (500 degrees C), and to rutile (700 degrees C). The activation energy of oxidation for NiTi is determined to be 51 kcal/mol when heating temperature is 500 degrees C or above. Since Ti reacts preferably with oxygen, Ni content increases between matrix and oxide, forming Ni3Ti compounds. Oxidation products decrease significantly the M, and A, temperatures in the specimen oxidized at 900 degrees C with B2 -> M transformation path. An extra calorimetric peak is found on cooling between two peaks in the specimen with B2 -> R -> M which was oxidized at 900 degrees C and aged at 500 degrees C. Oxidation deteriorates superelasticity due to formation of a Ni-rich compound. (c) 2007 Published by Elsevier B.V. English ELSEVIER SCIENCE SA TRANSFORMATIONS LAYER Effect of heat treatment temperature on oxidation behavior in Ni-Ti alloy Article 10.1016/j.msea.2006.12.221 1 MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, v.481, pp.658 - 661 MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 481 658 661 scie scopus 000255716100139 2-s2.0-41849099679 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Science & Technology - Other Topics Materials Science Metallurgy & Metallurgical Engineering Article; Proceedings Paper TRANSFORMATIONS LAYER oxidation Ni-rich zone transformation behavior extra peak superelasticity