Kinetic of oxidation of chromium-rich HfC-containing Co-based and Ni-based alloys between 1000 and 1100°C - Archive ouverte HAL Accéder directement au contenu
Poster De Conférence Année : 2014

Kinetic of oxidation of chromium-rich HfC-containing Co-based and Ni-based alloys between 1000 and 1100°C

Patrice Berthod

Résumé

Many cobalt-based superalloys and some nickel-based ones are reinforced by interdendritic carbides for allowing use them in hot conditions. Such carbides must be stable enough at high temperature in term of geometry/shape as well in term of volume fraction. The TaC carbides which reinforce some cobalt-based alloys do not rapidly evolve while TaC carbides are much less stable in chromium-rich nickel-based alloys (and even less stable than the chromium carbides in this second family of alloys). HfC are among the carbides which are more stable at high temperature than the tantalum carbides, much more in the case of the nickel-based alloys and already a little more in the case of the cobalt-based ones. Hafnium carbides may potentially lead to nickel-based and cobalt-based alloys very resistant against creep deformation at high temperature but it was recently found that the HfC carbides network may be rather neutral for the behaviour of the nickel-based alloys in oxidation at high temperature [6], but detrimental for the alloys which are based on cobalt. The good stability of the HfC carbides in the same families of alloys can be also exploited at lower temperatures such as 1100 and 1000°C. It appeared that interesting to characterize the behaviour in oxidation at these temperatures of the same alloys already studied at 1200°C, in order to see if the behaviour of the cobalt-based alloys notably is improved 100°C or 200°C lower. Obtaining dense HfC carbides reinforcing network led to Hf contents significantly higher than usual. This may be responsible of the bad oxidation behaviour observed for the cobalt alloys even for these two temperatures lower than the 1200°C at which they were previously tested. The very high temperature (1200°C) which was pointed out in previous works is not the single responsible of this based oxidation resistance. Besides Hf (which is not necessarily favourable when present in so high quantities) the chromium content a little too low for cobalt-based alloys probably merits to be augmented. Inversely, the nickel-based alloys present simultaneously dense HfC carbides and good resistance against high temperature oxidation. They appear as being ready for use at high temperature under mechanical stress in oxidant atmospheres.
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Dates et versions

hal-03476176 , version 1 (12-12-2021)

Identifiants

  • HAL Id : hal-03476176 , version 1

Citer

Elodie Conrath, Patrice Berthod. Kinetic of oxidation of chromium-rich HfC-containing Co-based and Ni-based alloys between 1000 and 1100°C. Eurocorr 2014, Sep 2014, Pise, Italy. ⟨hal-03476176⟩
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