Effect of Cr content on microstructure and oxidation resistance of Nb-Ti-Si-Cr based ultrahigh-temperature alloy

Li Qun Chen, Xi Ping Guo

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Ultrahigh-temperature alloys with the composition of Nb-22Ti-14Si-xCr-3Al-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)5Si3 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)5Si3 and Nbss/Cr2Nb eutectic colonies increase, while the amount of Nbss/(Nb, X)5Si3 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°C show that the amount of Ti0.4Cr0.3Nb0.3O2 and (Ti, Cr)NbO4 increase in the oxide scale with increase of Cr content in the alloys, while the contents of Nb2O5 and Ti2Nb10O29 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.

Original languageEnglish
Pages (from-to)30-36
Number of pages7
JournalCailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment
Volume34
Issue number5
StatePublished - May 2013

Keywords

  • Microstructure
  • Nb-Ti-Si-Cr based ultrahigh-temperature alloy
  • Oxidation resistance
  • Phase constituent

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