摘要
采用真空非自耗电弧熔炼方法制备了4种不同Cr含量的Nb-22Ti-14Si-xCr-3Al-5Hf-1.5B-0.06Y(x=0,10,14,20,at%)超高温合金。研究了Cr含量对合金的相组成、显微组织和高温抗氧化性能的影响。结果表明:不含Cr合金的组织由初生Nbss枝晶和Nbss/(Nb,X)5Si3共晶团组成,含Cr的3种合金中,初生相均为(Nb,X)5Si3,并出现了Nbss/Cr2Nb共晶团。随着Cr含量的增加,初生相(Nb,X)5Si3的含量增加,Nbss/Cr2Nb共晶团的含量增加,而Nbss/(Nb,X)5Si3共晶团的含量却减少,当Cr含量达到20 at%时,组织中未发现Nbss/(Nb,X)5Si3共晶团。1250℃的氧化实验表明:随着Cr含量的增加,氧化膜组织中Ti0.4Cr0.3Nb0.3O2和(Ti,Cr)NbO4含量增加,而Nb2O5和Ti2Nb10O29的含量却减少,氧化膜与基体结合程度加强,合金的高温抗氧化性能也随之增强。
Ultrahigh-temperature alloys with the composition of Nb-22Ti-14Si-xCr-3A1-5Hf-1.5B-0. 06Y （x = 0, 10, 14, 20, at% ） were prepared by vacuum non-consumable arc-melting. The effect of Cr content on the phase constituents, microstructure and high temperature oxidation resistance of the alloys was investigated. The results show that microstructure of the alloy without Cr is composed of Nbss dendrites and Nbss/（Nb, X）5Si3 eutectic colonies. The primary phase is （Nb, X）5 Si3 in the three alloys with different amount of Cr, while Nbss/Cr2Nb eutectic colonies are also observed. With increaing Cr content, the amount of primary phase （Nb, X）s Si3 and Nbss/ Cr2Nb eutectic colonies increase, while the amount of Nbss/（ Nb, X）5 Si3 eutectic colonies decrease. As the Cr content increasing to 20 at% , the Nbss/（ Nb, X）5Si3 eutectic colonies disappear. The results of oxidation test at 1250 ℃ show that the amount of Ti04 Cr03 Nb0.3 02 and （ Ti, Cr） NbO4 increase in the oxide scale with increase of Cr content in the alloys, while the contents of Nb2 05 and Ti2 Nbl0 029 in the oxide scale decrease. The high temperature oxidation resistance is improved due to the improvement of the binding ability of oxide scale with matrix.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2013年第5期30-36,共7页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金资助项目(No.51071124)
高等学校博士点基金项目(20096102110012)
西北工业大学凝固技术国家重点实验室自主研究课题(07-TP-2008)
国家"111"引智基金项目课题(B080401)
