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Poster De Conférence Année : 2004

Influence of the Microstructural Texture of Cast Superalloys on their High-Temperature Oxidation Behaviour

Résumé

The microstructure of alloys resulting from classical foundry practice depends on the solidification conditions. Local cooling rate and thermal gradient govern, respectively, grain size and dendritic orientation, then density and general orientation of grain boundaries. Grain boundaries acting as special diffusion paths for Cr atoms or O2- anions, the kinetic of high-temperature oxidation of superalloys could depend on both microstructural fineness and orientation. These points were studied for a Ni-base and three Co-base cast superalloys strengthened by carbides of different types (eutectic M23C6 and/or MC), the oxidation kinetics of which were measured by thermogravimetry under industrial air and at different high temperatures. The chemical composition is not the only alloy parameter having some influence of the high-temperature oxidation behaviour of carbide-strengthened cast superalloys. Indeed, it appeared here that both grain size and dendritic orientation must be taken into account, for example, when comparative oxidation tests are made in order to optimise the chemical composition of an alloy for improving its oxidation behaviour. But this influence, which seems also to depend on other chemical or microstructural parameters, is difficult to define and more work remains to be done for better understanding of the involved phenomena. First, tests at other temperatures are needed on all alloys in order to define the activation energies. Second, microprobe contents profiles and texture analysis of the chromia layer are required to understand the diffusion phenomena and their differences when grain size or dendritic orientation vary.
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hal-04020660 , version 1 (09-03-2023)

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Paternité - Pas d'utilisation commerciale - Pas de modification

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  • HAL Id : hal-04020660 , version 1

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Patrice Berthod, Simon Raude, Anne-Sophie Renck, Christophe Rapin, Renaud Podor, et al.. Influence of the Microstructural Texture of Cast Superalloys on their High-Temperature Oxidation Behaviour. 6th Symposium on High Temperature Corrosion and Protection of Materials (HTCPM6), May 2004, Les Embiez, France. ⟨hal-04020660⟩
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