Abstracto

Some examples of microstructure modifications induced by high temperature oxidation in cast chromium-rich refractory alloys strengthened by carbides

Patrice Berthod

Some of the cast metallic alloys for use at high temperature contain reinforcing carbides to notably resist creep. These may be eutectic carbides appeared during solidification, present in grain boundaries, with various volume fractions depending on the carbon content and with various compositions depending on the natures of the carbides-forming elements present. Such strong carbides-forming elements are generally also easier to oxidize than the base elements of the alloys and they play an important role in the high temperature oxidation of the alloy, often leading to special phenomena in the external oxide formed aswell as in the alloy just under the oxide-metal interface. In this work the oxidation behaviour at high temperature of selected alloys and superalloys reinforced by carbides of different types was investigated by notably considering these phenomena.