三元Cu—Ni—Fe合金在700—900℃空气中的氧化

AIR OXIDATION OF A TERNARV Cu-Ni-Fe ALLOY AT 700-900℃

研究了三元双相 Ｃｕ—３０Ｎｉ—２５Ｆｅ合金在 ７００—９００℃空气中的氧化在相同温度下合金的氧化速率都低于纯铜的，７００—８００℃的氧化动力学为抛物线规律，在９００℃初期为抛物线规律，后期变为线形规律，氧化膜最外层为近乎纯的氧化铜；内层是由三种金属组元的氧化物及组无间的复合氧化物所构成的混合区域，另外，在外氧化膜下面发生了Ｆｅ和Ｎｉ的内氧化，而内氧化区前沿的合金中仍保持为双相结构，该合金中难以发生Ｆｅ的选择性外氧化，这是组元间较小互溶度及合金双相结构限制了Ｆｅ的扩散的结果．

The air oxidation of a ternary two-phase Cu-30Ni-25Fe alloy has been studied at 700-900℃. The oxidation rate of the alloy is always slower than that of pure copper. The oxidation kinetics at 700 and 800 ℃ is parabolic, while at 900 ℃ there exists a gradual transition between an initial stage of parabolic to a second stage of approximately linear. The scales contain an outermost layer of almost pure copper oxide plus an inner region composed of the oxides of the three components as well as their double oxides. A relatively thin region of internal oxidation of Fe and Ni is also present, beneath which the alloy remains two-phase. The absence of an external oxidation of Fe in spite of its high content is attributed to the restrictions imposed to its diffusion in the metal substrate by the simultaneous presence of two metal phases and the limited mutual-solubility of the components.