Abstrait

Thermodynamic and experimental study of a cobalt-based alloy strengthened by tantalumcarbides

M�������������������������������©lissa Ritouet, Patrice Berthod

Eutectic TaC carbides are known as being particularly efficient for the high temperature strengthening of cast cobalt-based superalloys.The usual contents in carbon and tantalum may be advantageously increased to progress inmechanical performances at elevated temperature. In thiswork a chromiumrich (25wt.%Cr)TaC-reinforced cobalt-based superalloywas elaborated after preliminary thermodynamic calculations. The obtained microstructure, particularly rich in script-like shaped eutectic TaCmixed with the periphery part of the pre-eutectic dendrites of matrix, is furthermore free of any possible pre-eutectic TaC carbides. It lets hope very high creep resistance at high temperature, as preliminarily suggested by the rather high values of roomtemperature hardness.