Ce和Re对CoNiCrAlY合金1000℃氧化行为的影响  

Oxidation Behaviour of CoNiCrAlY at 1000 ℃ with Ce and Re Additions

作　　者：张玉朵[1] 张弛[1] 汪海锋[1] 杨志刚[1] 

机构地区：[1]清华大学材料学院先进材料教育部重点实验室,北京100084

出　　处：《稀有金属》2016年第5期409-414,共6页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51101091)资助

摘　　要：在热障涂层粘结层用CoNiCrAl Y合金中添加适量活性元素Ce和合金元素Re,1000℃空气气氛下进行恒温氧化,测试合金氧化动力学,采用X射线衍射(XRD)、扫描电镜/能谱(SEM/EDS)等手段观测氧化产物的物相组成和转变、氧化膜结构,进而比较添加适量活性元素Ce和合金元素Re对合金氧化行为的影响。结果表明,当前氧化条件下,合金氧化动力学可以划分为两个阶段:氧化初期,氧化速率较快;稳定氧化阶段,氧化产物由亚稳态θ-Al2O3转化成稳态α-Al2O3,氧化速率明显降低。CoNiCrAl Y合金表面形成了单一Al2O3膜,而CoNiCrAl YRe合金生成了富Cr氧化物外层+Al_2O_3内层双层氧化膜,并且在贫铝区形成了少量内氮化物。0.1%Ce(质量分数)的加入促进了Al的选择性氧化,加快了Al2O3的相转变,从而促进保护性α-Al2O3氧化膜的更快形成,使得CoNiCrAl Y合金稳定氧化阶段氧化速率常数由3.3×10^(-13)g^2·cm^(-4)·s^(-1)降低为1.5×10^(-13)g^2·cm^(-4)·s^(-1)。而且,Ce和Re元素共同存在时对合金抗氧化性能的改善效果更显著,CoNiCrAl YRe Ce合金表面形成了单一、连续、致密的Al_2O_3保护膜,Ce的加入使得含Re合金CoNiCrAl YRe的稳定氧化阶段氧化速率常数由2.8×10^(-13)g^2·cm^(-4)·s^(-1)降低为7.5×10^(-14)g^2·cm^(-4)·s^(-1)。Isothermal oxidation experiments of bondcoat alloy CoNiCrAlY in thermal barrier coating （TBC） were carried out at 1000 ℃ in static air with additions of reactive element Ce and alloy element Re. The oxidation kinetics was measured and the scale microstructure and phase compositions and transformation of oxides were analyzed by X-ray diffraction （XRD） and scanning electron microscopy equipped with energy dispersive X-ray spectrometer （SEM/EDS） to investigate the effect of reactive element Ce and alloy element Re additions on the oxidation behaviour of CoNiCrAlY. At the present oxidation conditions, oxidation kinetics was divided into two phases. In the phase of initial oxidation, the oxidation rate was rapid, fn the phase of stable oxidation, the oxidation rate reduced significantly with oxidation products changing from θ-Al2O3 to stable α-Al2O3. The Al2O3 external scale formed on the CoNiCrAlY alloy and a double-layer scale of Cr-rich oxides external layer ＋ Al2O3 internal layer formed on the CoNiCrA1YRe alloy, where internal nitridation was observed in the Al-depleted zone. With the addition of 0. 1% Ce （ mass fraction ） , the selective oxidation of aluminum and the phase transition of alumina were promoted significantly, which induced a faster development of protective Al2O3 oxide scale. The oxidation of CoNiCrAlY alloy was retarded by Ce addition in the stable oxidation stage corresponding to a decreased rate constant from 3.3 × 10^-13 g^2 ·cm^-4· s^- 1 to 1. 5× 10^-13 g^2·cm^-4·s-^1. An improvement in oxidation resistance was pronounced by the presence of cerium accompanied with rehnium. A continous and dense Al2O3 scale formed on the CoNiCrA1YReCe alloy. The rate constant of CoNiCrAlY- ReCe alloy in the stable oxidation stage decreased from 2.8 × 10^-13 g^2·cm^-4 s^-1 to 7.5 × 10^ -14 g^2·em^-4· s^-1 compared to that of the CoNiCrAlYRe alloy.

关 键 词：粘结层合金 高温氧化 铈 铼 

分 类 号：TG132.32[一般工业技术—材料科学与工程] TG146.45[金属学及工艺—合金]