High temperature microstructures of ternary Co-30wt.% Cr - based alloys over the [0 to 2.0wt.%] carbon range

International audienceThe Co-30wt.%-xC system was experimentally explored from x=0 to 2wt.%, by considering the stable microstructures at 1,000, 1,100 and 1,200°C, and the intervals of fusion. The strengthening potential and the refractoriness of several alloys belonging to this family were specified. Such simple alloys are able to display simultaneously a high amount of chromium for limiting hot corrosion, solidus temperatures as high as 1,300 °C and refractory carbides fractions that can reach 20 % in volume. Natures and fractions of carbides, and solidus temperatures were in good agreements with thermodynamic calculations. Inversely the measured liquidus temperatures were significantly higher than the calculated ones. In addition, thermodynamic modeling allowed to better interpret the disappearance of carbides due to oxidation at high temperature