High temperature oxidation behaviour of cast cobalt-based Cr-rich alloys reinforced by titanium carbides. Part 1: Mass gain kinetics - Archive ouverte HAL Accéder directement au contenu
Poster De Conférence Année : 2016

High temperature oxidation behaviour of cast cobalt-based Cr-rich alloys reinforced by titanium carbides. Part 1: Mass gain kinetics

Mira Khair
  • Fonction : Auteur
  • PersonId : 1061159
Patrice Berthod

Résumé

Cast Co-based Cr-rich alloys were among the earliest metallic alloys used for high temperature applications under oxidant atmos pheres [1,2]. The 20 to 30wt.% of chromium they containe d were the most ofte n enough to resist ox idation by hot gases and c orrosion by m olten substances [3]. Since they cannot take benefit from gamma prime precipitation as nickel-based s uperalloys their mechanical reinforcement must be achieved by solid solution strengthening and/or by pr imary (solidification) or secondary (heat-treatment) carbides precipitation. The most used carbides are chromium carbides, tungsten or molybde num carbides and tantalum carbides. More recently, hafnium carbides were also tested in great fractions in coba lt-based [4] but also iron-based [5] a nd nick el-based [6] chrom ium-rich cast refractory alloys. Among the best stable carbides at high temperature these are the MC ones which were the m ost frequently cited: TaC, HfC… TiC is also a metallic m onocarbide but this one seems having been rarely or ne ver considered as a strengthe ning carbide for alloys and superalloys working at high temperature. The purpose of this work is thus to start exploring the microstructures to which the presence of significant atomic contents in C and Tic lose to one a nother in addition-may lead, this by starting with the cast cobalt-based alloys family. Second, the beginning of discover of the high temperature properties of such alloys will start here with the isothermal high temperature oxidation beha viour. In this first part of the work these are the as-cast microstructures of the obtained alloys which will be on interest, together with the mass gain kinetic dur ing oxidation for several tens hours at temperatures ranging from 1000 and 1200°C in com parison with sim ilar alloys containing either chromium carbides or hafnium carbides. In a second part these are the results of post-mortem characterization of oxidation which will be described. The oxidation of the three studied TiC-containing cobalt-based alloys was generally parabolic at all the temperatures tested here, without tendency to detachment of the oxide scales as often observed for the ternary alloys, and without degeneration to linear oxidation after few hours or tens of hours of isothermal oxidation. In kinetic term they are similar to the ternary alloys while the Hf-containing alloys often oxidized much faster. If the HfC carbides are mechanically particularly interesting in cast chromium-rich alloys, notably for the high temperature creep resistance [8], they also lead to fast oxidation. One does not know at this time whether the TiC carbides will be so efficient in the high temperature strengthening of these alloys, but it clearly appeared here that they seem to do not threaten the oxidation resistance. In the second part of this work the oxidized samples will be subjected to post-mortem characterization in order to interpret the differences in mass gain kinetic observed here between these TiC-reinforced cobalt-based alloys and the corresponding ternary or HfC-strengthened alloys previously studied.
Fichier principal
Vignette du fichier
103 POSTER Eurocorr2016Montpellier MK PB.ppt [Mode de compatibilité].pdf (246.13 Ko) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)

Dates et versions

hal-03271529 , version 1 (25-06-2021)

Identifiants

  • HAL Id : hal-03271529 , version 1

Citer

Mira Khair, Patrice Berthod. High temperature oxidation behaviour of cast cobalt-based Cr-rich alloys reinforced by titanium carbides. Part 1: Mass gain kinetics. Eurocorr 2016, Sep 2016, Montpellier, France. ⟨hal-03271529⟩
18 Consultations
6 Téléchargements

Partager

Gmail Facebook X LinkedIn More