循環(huán)氧化行為
( 1. 寶山鋼鐵股份有限公司 技術中心， 上海 201900;
2. 中國科學院 金屬研究所 沈陽材料科學國家（聯(lián)合）實驗室， 沈陽 110016)
摘 要: 研究了2種成分相近的Ti3Al基合金(Ti-24Al-14Nb-3V-0.5Mo-0.3Si（摩爾分數(shù)）及Ti-24Al-14Nb-3V-0.5Mo-0.6Si在700~850 ℃空氣中的循環(huán)氧化行為； 重點考察了合金的循環(huán)氧化動力學行為；結合SEM/EDX及EPMA分析了循環(huán)氧化后樣品的表面、 斷面微觀形貌及斷面成膜元素面分布。結果表明： 2種合金在各氧化溫度下表面生成了Al2O3和TiO2混合氧化物， Al2O3主要分布在最外層；在700 ℃下2種合金具有較好的抗循環(huán)氧化性能， 而在800 ℃及以上的溫度條件下， 表面氧化膜易于開裂和剝落；合金在較高溫度下表面氧化膜失效方式為膜層中微裂紋的復合及由于這一過程的反復進行而導致的氧化膜間物理分層開裂。
關鍵字: Ti3Al基合金；循環(huán)氧化； 氧化動力學
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
