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Thermodynamic study, elaboration and high temperature oxidation of alloys highly strengthened by tantalum carbides. Part 3: Case of a Fe-30Cr-1C-15Ta alloy

Laura Corona , Patrice Berthod

This third part of the present work about chromium-rich alloys containing high amounts in carbon and tantalum, concerns a Fe-30Cr-1C-15Ta alloy. Its elaboration by high frequency induction foundry, here too after preliminary thermodynamic calculations, led to an alloy impoverished in tantalum by comparison with the targeted content and presenting a microstructure different from the one which was expected. The tantalum carbides were neither the single carbide phase nor present with volume fractions high enough to ensure high hardness. Finally, the alloy obtained, characterized by chromiumand tantalumcontents of 34 wt.%and 5.7 wt.% respectively, showed amicrostructure with a dendriticmatrix and numerous eutectic chromium carbides and tantalum carbides potentially useful for creep-resistance at high temperature. If its moderate hardness does not permit envisaging wear applications, the very good resistance to hot oxidation showed by the obtained alloy may be of interest for high temperature applications in aggressive gases.