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采用真空非自耗电弧熔炼法制备了成分为Nb-22Ti-15Si-5Cr-3Hf-3Al-x Zr(x=0,0.5,1,2,4和8,原子分数,%)的合金,研究了Zr含量对合金电弧熔炼态组织及高温抗氧化性能的影响.结果表明,6种不同Zr含量的合金均由Nb固溶体和g-(Nb,X)5Si3(X为Ti,Hf,Cr和Zr)组成,添加Zr并未改变合金的相组成,但随着Zr含量增加,合金中初生g-(Nb,X)5Si3的尺寸增大,含量提高.对不同Zr含量合金在1250℃分别氧化1~50 h发现,随着Zr含量的增加,合金氧化膜黏附性及致密性均得到显著改善,Zr含量较高的合金(x=4和8)氧化50 h后,氧化膜出现明显的分层现象:最外层为致密的单相Ti O2层,中间层主要由Zr O2,Ti Nb2O7和Ti O2组成,而内层主要由Si的氧化物组成.随着合金中Zr含量增加,氧化膜厚度及单位表面积的氧化增重均显著降低,抗氧化性能得到明显改善.
The alloy with Nb-22Ti-15Si-5Cr-3Hf-3Al-xZr (x = 0, 0.5, 1, 2, 4 and 8, atomic fraction,%) was prepared by vacuum non-consumable arc melting method. The effects of Zr content on the microstructure and high temperature oxidation resistance of the alloy during arc melting were investigated. The results show that all the six alloys with different Zr contents consist of Nb solid solution and g- (Nb, X) 5Si3 (X is Ti, Hf, Cr Zr), the addition of Zr did not change the phase composition of the alloy, but as the Zr content increased, the size of primary g- (Nb, X) 5Si3 increased and the content increased.For different Zr content alloy respectively oxidized at 1250 ℃ From 1 h to 50 h, the adhesion and densification of the oxide films were significantly improved with the increase of the Zr content. After the films with high Zr content (x = 4 and 8) were oxidized for 50 h, the oxide films showed obvious points Layer phenomenon: the outermost layer is a dense single-phase Ti O2 layer, the middle layer is mainly composed of Zr O2, Ti Nb2O7 and Ti O2, while the inner layer is mainly composed of Si oxide .As the Zr content in the alloy increases, the oxide film Both the thickness and unit surface area of oxidation weight gain were significantly reduced, the oxidation resistance was significantly improved.