添加Cu对Ti-16.28Si合金高温抗氧化行为的影响

Effect of Cu Addition on High Temperature Oxidation Behavior of Ti-16.28Si Alloy

选用Ti、Si、Cu粉末通过高能球磨-冷压-无压烧结制备了Ti-16.28Si和Ti-15.46Si-5Cu两种合金,并在800,900,1000℃空气中对其进行高温氧化试验。利用SEM、EDS及XRD对烧结和氧化试样的表面及横截面形貌、物相组成进行分析,以研究合金的氧化机制。结果表明:两种配方试样烧结之后主要含有Ti、Ti_5Si_3、Ti_5Si_4相,加Cu配方出现Cu_3Si相;加Cu后致密度升高。高温氧化80h后,氧化试样的主要物相为TiO_2,还含有少量的SiO_2、Ti_3O_5、TiO、CuO或Cu_2O相。Ti-16.28Si合金在900℃时氧化膜表层基本上全是金红石TiO_2,抗氧化性能最好,平均氧化速度k^+值约为0.521,达到抗氧化等级。800℃下,添加Cu显著改善Ti-16.28Si合金的抗氧化性能,其平均氧化速度k^+值约为0.623,也达到抗氧化等级;在Cu含量为5%(质量分数)时其平均氧化速度仅为Ti-16.28Si合金的57.8%。但在900和1000℃下,添加Cu降低了合金的抗氧化性能。

Ti-16.28Si and Ti-15.46Si-5Cu alloys were prepared by high-energy ball milling, cold-pressureless sintering using Ti, Si and Cu powder as starting materials. High temperature oxidation tests were performed at 800 ℃, 900 ℃, and 1000 ℃ in air. The surface and cross-section morphologies and phase composition of sintered and oxidized samples were investigated by SEM, EDS and XRD. The results show that two kinds of formula samples are mainly composed of Ti, TisSi3 and TisSi4 phases after sintering, while Cu3Si phase appear after adding Cu. The density increases with Cu addition. The main phase of the oxidized samples for 80 h is TiO2, with a small amount of SiO2, Ti305, TiO, and CuO or Cu20 phases. Ti-16.28Si alloy possesses the best oxidation resistance at 900 ℃ with the single rutile TiO2 phase nearly, and it reaches antioxidant levels with k＋（0.521）. At 800 ℃, Cu significantly improves the oxidation resistance of Ti-16.28Si alloy and the alloy reaches antioxidant levels with k^（0.623）. Compared to Ti-16.28Si alloy, the average oxidation speed of Ti-15.46Si-5Cu is 57.8%. However, at 900 ℃ and 1000 ℃, the oxidation resistance of Ti-16.28Si alloy declines with Cu addition.