中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 22 No. 7 July 2012 |
（1. College of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
3. Hunan Electric Power Corporation Research Institute, Changsha 410007, China）
Abstract:The isothermal oxidation behavior of NiAl-31Cr-2.9Mo-0.1Hf-0.05Ho directional eutectic alloy was investigated with the help of scanning electron microscopy and X-ray diffraction. The results revealed that a continuous Al2O3 scale was formed and owned excellent oxidation resistance in the temperature range of 900-1100 °C. When the temperature was up to 1150 °C, the continuous Al2O3 oxide film ruptured. Trace rare earth element Ho distributed uniformly in the alloy and relatively high level of Al in Cr(Mo) phase are beneficial to the formation of continuous and compact Al2O3 scale. During the oxidation, a phase transformation from θ-Al2O3 to α-Al2O3 existed on the surface of oxidation film. It resulted in the abnormal oxidation mass gain happening when the alloy was oxidized at 1000 °C or 1050 °C.
Key words: intermetallic compounds; NiAl; high temperature oxidation; directional eutectic alloy
