三元Co-Ni-Al合金在800~1000℃纯氧中的氧化行为研究

Oxidation Behavior of Ternary Alloys Co-20Ni-3Al and Co-20Ni-5Al in 10~5 PaO2 Atmosphere at 800-1000 ℃

研究了三元Co-20Ni-x Al (x=3,5,质量分数,%)合金在纯氧中800~1000℃下20 h的氧化行为。氧化后,两种合金表面均生成了双层结构外氧化膜,外层膜主要由CoO与少量NiO组成,而内层膜则为CoO与尖晶石的混合物,外氧化膜下为铝的内氧化区。合金的氧化速率随氧化温度的升高而增大;合金中Al含量由3%增加到5%,Co-20Ni-Al合金的氧化速率随之下降,但5%Al仍不足以使合金表面生成保护性的单一氧化铝膜。

The oxidation behavior of two ternary alloys Co-20Ni-x Al(x=3, 5, mass fraction, %) was studied in 105PaOat 800-1000 ℃ for 20 h. After oxidation, the two alloys all formed double-layered external scales composed of an outer layer of CoO(with a small amount of NiO) and an inner layer of mixtures CoO and spinels, usually followed by a region of internal oxidation of Al. The oxidation rate of the alloys increases with the increasing temperature. When the increase of Al content from 3% to 5%, the oxidation rate of Co-Ni-Al alloys is reduced, however, the Al content of 5% is not yet sufficient to ensure the formation of a protective external alumina scale on the alloy. In fact, the experimental results may be well interpreted by the prediction according to the theoretical mode related to the reaction of binary alloy with single oxidant by simplifying the ternary Co-Ni-Al alloys as binary(Co-Ni)-Al alloys.