Fe-Cu纳米涂层在700与800℃空气中的氧化

AIR OXIDATION OF TWO Fe-Cu NANOCRYSTALLINE COATINGS AT 700 ℃ AND 800 ℃

利用磁控溅射技术制备了Ｆｅ含量（质量分数，％）分别为２５和５０的两种Ｆｅ－Ｃｕ纳米涂层，并研究了该涂层在７００与 ８００ ℃空气中的氧化结果表明， Ｆｅ—７５Ｃｕ涂层氧化后形成了外层为氧化铜和内侧为氧化铁的复合氧化膜，而 Ｆｅ—５０Ｃｕ发生了 Ｆｅ的单一外氧化，其氧化特征均有别于同成分的铸态合金这种氧化机制在于晶粒尺寸细化显著扩展了 Ｆｅ在 Ｃｕ中的溶解度，同时大量的晶界也为组元扩散提供了短路通道。

Two Fe-Cu nanocrystalline coatings containing 25 and 50 Fe(mass fraction,%) have been prepared using magnetron sputtering, and their air oxidation behaviors were also studied at 700℃ and 800 ℃. The results showed that a duplex oxide scale composed of an outermost layer of pure copper oxide plus a continuous inner layer of iron oxide formed for Fe-75Cu coatings, while a single external scale of iron oxide was observed for Fe-50Cu coatings. The oxidation characteristics are significantly different from those of as-cast alloys with the same composition. The oxidation mechanism is attributed to an extension of solid solubility of iron in copper induced by the reduction of grain size in the coatings, which also provided a large number of short-circuit diffusion paths for the elements. A conclusion is drawn that for two-phase systems that are virtually immiscible, the critical concentration for the transaction from internal oxidation to exclusive external oxidation of the most active element can be effectively reduced with the nanocrystallization of the grain size.