Fe－Nb合金在600－800℃，0．1MPa纯氧中的氧化

OXIDATION OF Fe-Nb ALLOYS UNDER 0.1 Mpa PURE OXYGEN AT 600─800℃

研究了Ｆｅ－１５Ｎｂ和Ｆｅ－３０Ｎｂ合金在６００－８００℃，０．１ＭＰａ纯氧中的氧化行为。结果表明，氧化过程遵循近似的抛物线规律，与相同条件下的纯铁相比，合金的氧化速率常数低得多，所生成的外氧化膜为弥散的二元Ｆｅ－Ｎｂ氧化物和Ｆｅ２Ｏ３，但不含有ＦｅＯ与Ｆｅ３Ｏ４．合金不发生内氧化和Ｎｂ的局部贫化现象，基于Ｆｅ－Ｎｂ－Ｏ三元相图，考虑到Ｎｂ在基体金属中的低溶解度和合金为两相组织的影响。

The oxidation of two Fe-Nb alloys containing 15 and 30% Nb(mass fraction) has been studied at 600─800℃ under 0.1 MPa pure oxygen.The reaction followed the parabolic rate law to a reasonable approximation with rate constants much lower than that for the oxidation of pure iron under the same condition. Internal oxidation and depletion of niobium in the alloy have not been observed. The external scales were composed of Fe2O3 and a dispersion of double Fe-Nb oxide, while FeO and Fe2O3 were not observed.The oxidation behavior of these alloys is interpreted with reference to an approximate phase diagram of the ternary system Fe-Nb-O, taking into account the effects of the low solubility of niobium in the base metal and of the presence of two metallic phases in the alloy.