Oxidation behavior and mechanism of a Ni-based single crystal superalloy with single α-Al 2 O 3 film at 1000 °C

Haiqing Pei, Zhixun Wen, Yamin Zhang, Zhufeng Yue

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Abstract

Detailed long-term of 2000 h oxidation behavior of a Ni-based single crystal superalloy was investigated at 1000 °C. In the first oxidation stage, α-Al 2 O 3 formed immediately, and then the mass gain curve obeys the parabolic law, which corresponds to the growth of α-Al 2 O 3 film. A single α-Al 2 O 3 film kept on the surface of the specimen before 750 h oxidation. The oxidation is controlled by the inward diffusion of oxygen anions to react with Al cations at the oxide/metal interface. The shape of the exfoliation region of single α-Al 2 O 3 film is closed to an annulus, in which the (Ni, Co)O layer formed due to depletion of Al. The three-layer oxide scale formed rapidly after 750 h oxidation. With the continue consumption of Al, a discontinuous inner α-Al 2 O 3 layer formed, making oxide scale spall seriously and gain mass rapidly. The states of α-Al 2 O 3 film, the controlled film, are different in dendrite core and interdendritic region.

Original languageEnglish
Pages (from-to)124-135
Number of pages12
JournalApplied Surface Science
Volume411
DOIs
StatePublished - 31 Jul 2017

Keywords

  • Diffusion
  • Ni-based single crystal superalloys
  • Oxidation mechanism
  • Single α-Al2O3 film

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