Abstrait

Beginning of oxidation during heating in the case of cast nickel based alloys containing carbides of chromium and/or tantalum

Patrice Berthod

The heating parts of thermogravimetry curves initially performed with alloys or superalloys for studying their behaviour in isothermal oxidation, can be easily corrected from the ArchimedeÂ’s thrust in order to examine how oxidation acts during the heating. This was done in this work for several cast nickel-based alloys, a binaryNi-30Cr, six ternaryNi-30Cr-(0.2 to 2.0)C and three quaternary alloys containing Ta, for the same heating rate. The temperatures at which oxidation induced mass gains high enough to be detectable were all higher than 800°C, but with a reproducibility which can depend on the presence of tantalum for example. The total mass gain obtained at the end of heating was also studied versus the chemical composition of the alloys. Tantalum enhances oxidation during heating.