微量Dy元素影响NiAl金属间化合物超高温氧化性能及其机理的研究

项目名称： 微量Dy元素影响NiAl金属间化合物超高温氧化性能及其机理的研究

项目编号： No.50801003

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 无线电电子学、电信技术

项目作者： 吴红丽

作者单位： 北京航空航天大学

项目金额： 20万元

中文摘要： NiAl 金属间化合物以密度低、熔点高等优势，成为满足新一代燃气涡轮发动机用1200℃#20197;上超高温材料的候选材料。实验研究发现：微量Dy元素的添加明显降低了NiAl的氧化速率，增强了氧化层和基体之间的粘合力，同时有效削弱了氧化层和基体界面处孔洞的产生，显著提高了NiAl合金的抗氧化性能。采用第一性原理计算方法对Dy元素的作用机制研究表明：Dy元素显著改变了NiAl的电子结构及其原子中电子间的相互作用，且Dy在NiAl晶格中的占位与其化学计量比和温度息息相关，而掺杂原子的占位情况对其性能有显著影响，且Dy元素的掺杂显著增加了Ni原子迁移所需要的能量，限制了Ni原子的扩散，进而有利于减少了孔洞的形成和缓解氧化膜的剥落，计算结果与实验结果相吻合，这些微观电子结构的变化均有利于提高NiAl金属间化合物的高温抗氧化性能。本项目研究结果将为探索研究NiAl乃至航空用金属间化合物体系的高温氧化理论提供依据。

中文关键词： NiAl金属间化合物；高温氧化；电子结构；原子扩散

英文摘要： NiAl intermetallic compounds are candidate materials for the new generation engines in the temperature higher than 1200℃owing to its lower density, high melting points and so on. The experimental results show that the trace amount of Dy can significantly reduce the oxidation rate of NiAl, strengthen the Al2O3/NiAl interfacial cohesion and weaken the defects/holes formation, which are all benifitial to improve the oxidation resistant proerty of NiAl. The first principles method is introduced to invesitigate the oxidation mechanism. The calculation results show that Dy has noteble effect on the electronic strutures and the electronic interactions among the atoms in NiAl lattice. Moreover, the site preference of Dy in NiAl is closely related with the stoichiometry and temperatures, which has important effect on the macro properties. In addtion, Dy significantly increases the energy barrier for the diffusion of Ni atom and restricts its migration, which will result in the decrease in the number of the defects and the alleviation of the spallation. The calculation results well agree with the experimental results. All these changes at the electronic level are respossible for the macro oxidation resistance improvement of NiAl inermetallic. It is believed this work can provide experimental and theoretical information for establishing oxidation theory of intermetalics for the whole aeronautics applications.

英文关键词： NiAl intermetallic compound;High-temperature oxidation;Electronic structure; Atomic diffusion