扩散处理对离子镀铝TiAl合金高温氧化性能的影响

Effect of diffusion treatment on high temperature oxidation property of multi-arc ion plating aluminum coatings on TiAl alloy

利用多弧离子镀技术在TiAl合金表面制备纯铝层,分别进行720℃×2 h、780℃×2 h和840℃×2 h高温扩散处理,采用SEM、EDS和XRD分析了扩散铝层的微观组织及其相组成,并测试了不同扩散热处理工艺对合金高温氧化性能的影响。结果表明:随着扩散温度升高,镀铝扩散层厚度不断增加,扩散层由表及里形成Al2O3/TiAl3/TiAl2的结构特征,且内部Al元素浓度呈梯度分布;镀铝经扩散处理后的TiAl合金在850℃空气中的氧化速度主要受扩散层元素与基体元素之间的热扩散过程控制。氧化动力学曲线呈对数变化规律。当扩散工艺为840℃×2 h时,镀铝扩散层具有优良的抗高温氧化性能。

Aluminum coatings were deposited on TiAI alloy by multi-arc ion plating （MAIP） and then diffusion-treated under 720 ℃, 780 ℃ and 840 ℃ for 2 h, respectively. Microstructure, chemical composition and phase constituent of the Al-diffusion coatings were analyzed by SEM, EDS and XRD. The high temperature oxidation resistance of the coatings with different diffusion treatments was tested. The results show that the A1 plating coatings are transformed to A12O3/TiAI3/TiA12 from top to inner by diffusion process at elevated temperature. The content of A1 is gradually decreased. The oxidation velocity of the AI diffusion coatings is controlled by the diffusion process of elements between the coating and the substrate at 850 ℃. The oxidation kinetics curves present logarithmic change rule. With diffusion treatment under 840 ℃×2 h, the AI diffusion coatings exhibit excellent high temperature oxidation resistance.