ZTNM钛铝合金高温氧化行为及机制研究

Study on High-Temperature Oxidation Behavior and Mechanisms of ZTNM TiAl Alloys

摘要:

以铸造钛铝合金ZTNM为研究对象，依据HB5258标准并结合循环氧化实验，系统研究了该合金在650和750 ℃循环氧化行为。结果表明，2种温度下合金的氧化增重动力学曲线均呈抛物线规律，650 ℃氧化速率（k''_{650 ℃}=0.0082 g?m^-2?h^-1）低于750 ℃（k''_{750 ℃}=0.0095 g?m^-2?h^-1），且在2个温度下氧化速率均达到完全抗氧化级。氧化过程可分为3个阶段：氧化初期生成TiO₂+Al₂O₃膜；中期在膜/基体界面处形成连续TiN/Ti₂AlN氮化物层，长期则在氧化膜中出现贫Al区。更高温度（750 ℃）促进了TiO₂的快速生长，使氧化膜更厚，氮化物层是决定氧化速率及氧化膜结构稳定性的关键因素。

Abstract:

The cyclic oxidation behavior of a cast ZTNM TiAl alloy at 650 and 750 ℃ in accordance with the HB5258 standard was investigated. The results indicate that the oxidation mass gain kinetics of the alloy at both temperatures follows a parabolic law. The oxidation rate at 650 ℃ (k''= 0.0082 g?m^-2?h^-1) is lower than that at 750 ℃ (k''= 0.0095 g?m^-2?h^-1), with both rates qualified as “complete anti-oxidation” grade. The oxidation process contains three distinct stages: the initial formation of a mixed TiO₂ and Al₂O₃ scale; the development of a continuous TiN/Ti₂AlN nitride layer at the scale/metal substrate interface during the intermediate stage; the formation of an Al-depleted zone within the oxide scale after long-term exposure. The higher temperature (750 ℃) promotes the growth of TiO₂, resulting in a thicker oxide scale. The nitride layer plays a critical role in determining the oxidation rate and the structural stability of the scale.