摘要
Nanocrystalline CoCrAlY overlay coating was prepared on M38G superalloy by magnetron sputtering deposition. To investigate the oxidation behavior and phase transformation of alumina during oxidation, the oxidation experiments were conducted at 1 050 ℃ for various time in the range of 5?180 min. The phase compositions of the oxide scales were investigated by using glancing angle X-ray diffraction(XRD). The microstructure analysis of oxide scales was carried out by means of scanning electron microscopy(SEM). The growth process of metastable alumina at the grain boundaries and transformation to stable alumina were discussed. The results show that at the initial oxidation stage the mixture of δ-Al2O3, γ-Al2O3 and α-Al2O3 is formed on the sample surface rapidly. Especially, δ-Al2O3 and γ-Al2O3 prefer growing at the grain boundaries of CoCrAlY coating. With increasing oxidation time, δ-Al2O3 and γ-Al2O3 transform to θ-Al2O3, afterwards θ-Al2O3 transforms to α-Al2O3 gradually. After 180 min oxidation, θ-Al2O3 transforms into α-Al2O3 completely.
Nanocrystalline CoCrA1Y overlay coating was prepared on M38G superalloy by magnetron sputtering deposition. To investigate the oxidation behavior and phase transformation of alumina during oxidation, the oxidation experiments were conducted at 1 050 ℃ for various time in the range of 5-180 min. The phase compositions of the oxide scales were investigated by using glancing angle X-ray diffraction（XRD）. The microstructure analysis of oxide scales was carried out by means of scanning electron microscopy（SEM）. The growth process of metastable alumina at the grain boundaries and transformation to stable alumina were discussed. The results show that at the initial oxidation stage the mixture of δ-Al2O3, γ-Al2O3 and α-Al2O3 is formed on the sample surface rapidly. Especially, δ-Al2O3 and γ-Al2O3 prefer growing at the grain boundaries of CoCrA1Y coating. With increasing oxidation time, δ-Al2O3 and γ-Al2O3 transform to θ-Al2O3, afterwards θ-Al2O3 transforms to α-Al2O3 gradually. After 180 min oxidation, θ-Al2O3 transforms into α-Al2O3 completely.
出处
《中国有色金属学会会刊：英文版》
CSCD
2007年第3期595-599,共5页
Transactions of Nonferrous Metals Society of China
基金
Project(50371095) supported by the National Natural Science Foundation of China
