含Er高NbTiAl基合金抗循环氧化性能研究

STUDY ON CYCLIC OXIDATION RESISTANCE OF HIGH NIOBIUM CONTAINING TiAl BASE ALLOY WITH ERBIUM

采用水冷Cu坩埚真空感应悬浮熔炼技术制备了Ti-46Al-8Nb和Ti-46Al-8Nb-0.1Er合金.根据氧化动力学,结合XRD,SEM和EDS分析氧化层的相结构、显微组织及与基体合金的界面特征,测试了合金在900℃的抗循环氧化性能.结果表明,2种合金循环氧化100 h,100 cyc均未见氧化膜剥落,Ti-46Al-8Nb-0.1Er较Ti-46Al-8Nb表现出更优良的抗氧化性能,氧化后第二层混合氧化物主要由Al_2O_3组成,连续致密且与基体良好结合的氧化膜可明显降低合金的氧化速率、减小氧化增重及氧化膜厚度.Er净化了合金基体,阻止O原子内向扩散,并促进TiAl氧化膜中的Al_2O_3形成,从而提高TiAl基合金的抗循环氧化性能.

Ti-46Al-8Nb and Ti-46Al-8Nb-0.1Er alloys were prepared by the cold crucible induction levitation melting method. The oxidation behavior experiment was done in air at 900℃ up to one hundred times. Based on the oxidation kinetic analysis and the phase constitution, microstructure and the interface of the oxidation film and the matrix were investigated by means of XRD and SEM equipped with EDS, the cyclic oxidation resistance of TiAl based alloys was explored. The results showed that no spallation of layer occurs in both alloys, and Ti-46Al-8Nb-0.1Er comparing with Ti-46Al-8Nb exhibits more excellent oxidation resistance, oxides formed on the surface consist of mainly Al2O3, the continuous compact oxidation film with a good combination with the matrix significantly decreases the oxidation rate, the mass gain and the oxide film thickness. The addition Er purifies the alloy matrix and prevents the inward diffusion of oxygen atoms, thereby improves the cyclic oxidation resistance of TiAl based alloy.