Title: The Influence of Microstructure on the Isothermal and Cyclic Oxidation Behaviour of Ti-48Al-2Cr at 800 C.
Citation: Oxidation of Metals vol. 48 p. 263-287
Publication Year: 1997
JRC N°: JRC14323
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC14323
Type: Articles in periodicals and books
Abstract: The isothermal and cyclic oxidation behaviour of the intermetallic Ti-48Al-2Cr (at.%) alloy were studied at 800 C in air. Emphasis was placed on the effect of microstructures, in a range relevant for practical applications; i.e., duplex, near gamma, nearly lamellar, and fully lamellar, obtained by various heat treatments. The oxidation kinetics of the intermetallic alloy showed initially the formation of a relatively protective oxide scale. After an exposure time of about 10 h the oxidation rate increased significantly, due to a loss of protectivity of the oxide scale. The growth rate of the oxide scale, as well as its composition, structure and morphology showed no major relation to the microstructure of the based material. The oxidation of Ti-48Al-2Cr in air, initially resulted in the formation of alfa-Al2O3, TiO2 (rutile), Ti2AlN and TiN. After longer exposure times, the mixed oxide scale with an alumina rich layer at the outside was overgrown by the fast growing TiO2, responsible for the fast growing kinetics. Using 18O/15N experiments some mechanistic aspects were discussed in relation to the existence of a nitrogen-rich layer near the scale/alloy interface. Thermal cyclic oxidation experiments up to 3000 one hour cycles showed that spallation of the oxide scale initiated after about 175 one hour cycles. Also in this case the growth rate of the oxide scale as well as its composition, structure and morphology showed no major relation to the microstrtucture of the base material.
JRC Directorate:Joint Research Centre Historical Collection

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