Abstract
The oxidation behaviour of model Co–Re based alloys at 1000°C in air has been investigated. Thermogravimetric studies in combination with microstructural examinations of Co–Re alloys with different compositions showed the negative influence on the oxidation resistance of Co based alloys due to the evaporation of rhenium oxide(s). Oxidation at 1000°C in air yielded an oxide scale, which consists of a Co oxide outer layer on a thick and porous mixed Co–Cr oxide and a semicontinuous and therefore non-protective Cr oxide film on the base metal substrate. This allows the vaporisation of rhenium oxide formed during oxidation and leads to a loss of Re. In addition, computer aided thermodynamic calculations were carried out to supplement the experimental analyses.
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