School of Materials Science and Engineering, Tongji University, Shanghai, 201804, P.R. China.
Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Ontario, M5B 2K3, Canada.
Sci Rep. 2017 Jun 14;7(1):3483. doi: 10.1038/s41598-017-03690-0.
Oxidation resistance is one of key properties of titanium aluminide (TiAl) based alloys for high-temperature applications such as in advanced aero-engines and gas turbines. A new TiAlNbCr alloy with micro-addition of yttrium has been developed, but its oxidation behavior is unknown. To provide some fundamental insights, high-temperature oxidation characteristics of this alloy are examined via scanning electron microscopy, transmission electron microscopy, electron probe microanalysis, and X-ray diffraction. We show that distinctive core-multishell globular oxidation and "daisy" flower-like oxidation occur exclusively around YO particles. Globular oxides exhibit multi-layered YO/TiO/AlO-rich/TiO-rich shell structures from the inside to outside. Flower-like inner oxides consist of core YO particles surrounded by divergent AlO and oxygen-rich α-TiAl in the near-scale substrate. As the scale-substrate interface moves inward, the inner oxide structures suffer deeper oxidation and transform into the globular oxide structures. Our results demonstrate that the unique oxidation characteristics and the understanding of formation mechanisms pave the way for the exploration and development of advanced oxidation-resistant TiAl-based materials.
抗氧化性是钛铝合金（TiAl）基高温应用合金（如先进航空发动机和燃气轮机）的关键性能之一。已经开发出一种具有微添加钇的新型 TiAlNbCr 合金，但它的氧化行为尚不清楚。为了提供一些基本的见解，通过扫描电子显微镜、透射电子显微镜、电子探针微分析和 X 射线衍射研究了该合金的高温氧化特性。我们表明，独特的核-多壳层球状氧化和“雏菊”花样氧化仅在 YO 颗粒周围发生。球状氧化物表现出从内到外的多层 YO/TiO/AlO 富/TiO 富壳结构。花样内氧化物由核心 YO 颗粒组成，周围是发散的 AlO 和近尺度基底中的富氧 α-TiAl。随着尺度-基底界面向内移动，内氧化物结构受到更深的氧化，并转化为球状氧化物结构。我们的结果表明，独特的氧化特性和形成机制的理解为探索和开发先进的抗氧化 TiAl 基材料铺平了道路。
