离子注钇对Co-40Cr合金900℃氧化行为的影响

Influence of Yttrium Implantation on Oxidation Behavior of Co 40Cr Alloy at 900 ℃

研究了离子注Ｙ对Ｃｏ４０Ｃｒ合金在９００℃空气中氧化行为的影响。采用扫描电镜能谱（ＳＥＭＥＤＸＳ）、二次离子质谱（ＳＩＭＳ）、透射电镜（ＴＥＭ）和高分辨电子显微镜（ＨＲＥＭ）等实验手段对合金表面氧化膜的生长机制进行了研究。结果表明，离子注入Ｙ降低了合金表面Ｃｒ的结合能，有利于氧化初始阶段Ｃｒ２Ｏ３膜的快速形核；同时，注Ｙ后增大了氧化膜内Ｃｒ的结合能，对Ｃｒ３＋阳离子在氧化膜内的扩散传质起到了阻碍作用。离子注Ｙ在细化Ｃｒ２Ｏ３氧化膜晶粒的同时也降低了氧化膜的生长速率。ＳＩＭＳ和ＴＥＭＨＲＥＭ研究表明，注入的Ｙ氧化后主要存在于氧化膜的外侧，即靠近氧化膜气体界面附近的氧化膜中，以ＹＣｒ２Ｏ３第二相颗粒的形式分布在Ｃｒ２Ｏ３晶界上，仅有极少量Ｙ２Ｏ３颗粒存在于氧化膜合金界面附近的氧化膜中。除此之外，Ｙ还可能以离子的形式偏聚于Ｃｒ２Ｏ３晶界，阻碍氧化膜中离子扩散和改善膜的力学性能。

The oxidation behavior of Co 40Cr alloy with and without yttrium implantation has been studied at 900 ℃ in air. SEM、 SIMS and TEM/HREM have been used to study the growing mechanism of oxide scale formed on the alloy. It is found that the binding energy of Cr on the alloy surface was decreased by yttrium implantation, it accelerates the formation of protective Cr 2O 3 scale on the substrate. In the mean time, the binding energy of Cr inside the oxide scale is increased by yttrium implantation, and this will delay the Cr 3+ cation diffusion through the scale. Yttrium implantation has decreased the oxide scale's grain size and the growing speed. SIMS and TEM/HREM results show that some yttrium exists as YCrO 3 small particles at Cr 2O 3 grain boundary, near the oxide/gas interface, and very few Y 2O 3 small particles exist near the substrate/oxide interface. Besides, yttrium may also segregate to Cr 2O 3 grain boundary as Y 3+ ions, delay Cr 3+ cation diffusion and change the mechanical properties of the oxide scale. The ability of anti oxidation of Co 40Cr alloy is greatly improved by yttrium implantation.