循环氧化行为
( 1. 宝山钢铁股份有限公司 技术中心， 上海 201900;
2. 中国科学院 金属研究所 沈阳材料科学国家（联合）实验室， 沈阳 110016)
摘 要: 研究了2种成分相近的Ti3Al基合金(Ti-24Al-14Nb-3V-0.5Mo-0.3Si（摩尔分数）及Ti-24Al-14Nb-3V-0.5Mo-0.6Si在700~850 ℃空气中的循环氧化行为； 重点考察了合金的循环氧化动力学行为；结合SEM/EDX及EPMA分析了循环氧化后样品的表面、 断面微观形貌及断面成膜元素面分布。结果表明： 2种合金在各氧化温度下表面生成了Al2O3和TiO2混合氧化物， Al2O3主要分布在最外层；在700 ℃下2种合金具有较好的抗循环氧化性能， 而在800 ℃及以上的温度条件下， 表面氧化膜易于开裂和剥落；合金在较高温度下表面氧化膜失效方式为膜层中微裂纹的复合及由于这一过程的反复进行而导致的氧化膜间物理分层开裂。
关键字: Ti3Al基合金；循环氧化； 氧化动力学
700-850 ℃ in air
（ 1. Technology Center, Bao Shan Iron & Steel Company Ltd., Shanghai 201900, China;
2. Shenyang National Laboratory for Materials Science,
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract: The cyclic oxidation behaviors of two Ti3Al-based alloys with similar content of Ti-24Al-14Nb-3V-0.5Mo-0.3Si（molar fraction, %）and Ti-24Al-14Nb-3V-0.5Mo-0.6Si at 700-850 ℃ in air were investigated. The emphasis was placed on the characteristics of cyclic oxidation kinetics, the microstructure of surface and cross-section of oxide scales and the depth profiles of alloying elements by means of XRD/EDX and EPMA. The results show that during the oxidation process, the mixture of Al2O3 and TiO2 is formed and the outside layer is enriched with Al. Cyclic oxidation resistance of these two Ti3Al-based alloys is good at 700 ℃. But at 800 ℃ or above that, the surface oxide is prone to cracking and spallation. The failure mode of the oxide scale at higher temperatures is contributed to the physical delamination in the scales due to the initiation and propagation of micro-cracks and during the cyclic oxidation process.
Key words: Ti3Al-based alloy; cyclic oxidation; oxidation kinetics
