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Effect of Mo on microstructure and oxidation of NiCoCrAlY coatings on high Nb containing TiAl alloys

Research output: Contribution to journalArticlepeer-review

Abstract

In order to improve the oxidation resistance of high Nb containing TiAl alloys, the microstructure and oxidation behavior of NiCoCrAlY(Mo) coatings were investigated at 900 °C for 100 h by isothermal oxidation tests. The oxidation resistance of TiAlNbCr alloys was significantly improved after adding coatings and the oxidation resistance of NiCoCrAlY coating was slightly better than that of NiCoCrAlYMo coating. A continuous and dense Al 2 O 3 film was formed on the surface of NiCoCrAlY coating. Mo has negative influence on the oxidation resistance of NiCoCrAlY coating. It is found that Mo was oxidized to form MoO 3 , meanwhile the evaporation of MoO 3 resulted in the spallation of oxide film and severe internal oxidation. However, Mo was beneficial to enhance the adhesion between coating and substrate due to the formation of Al 2 O 3 pegs. Elemental interdiffusion at the interface of coating-alloy was inhibited by the MoO 3 and Al 2 O 3 diffusion barriers effectively.

Original languageEnglish
Pages (from-to)81-92
Number of pages12
JournalApplied Surface Science
Volume431
DOIs
StatePublished - 15 Feb 2018

Keywords

  • Mo
  • NiCoCrAlY coating
  • Oxidation
  • Plasma spraying
  • TiAlNbCr alloy

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