Abstrakt

Determination of the real global or local carbon contents in a high temperature alloy by using thermodynamic calculations

Patrice Berthod

Oxidation of the molten bath during oxidation, as well as oxidation in service at high temperature can lead to a global or a local impoverishment of the carbon contained in an alloy. The determination of the carbon content was achieved by using thermodynamic calculations first for a Co(bal.)-Cr- C-Ta alloy elaborated by foundry in a not totally inert atmosphere, and second after oxidation for 50 hours at 1,000°C, 1,100°C and 1,200°C. The association ofmetallographic quantifications,micro-analysismeasurements and calculated results with iterations about the carbon content, allowed to assess the loss of all the elements during casting and to specify the new distribution of carbon in the sub-surface affected by oxidation.