Effect of Ta on microstructure and phase distribution in cyclic oxidized Ir-Ta modified aluminide coatings on nickel base single crystal superalloy

P. Kuppusami, H. Murakami

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Abstract

The effect of Ir-Ta coating (with varying amounts of Ta) on microstructure, composition variation and phase distribution in the modified aluminides on Ni-base single crystal superalloy, TMS-75 subjected to cyclic oxidation has been investigated. Ir-Ta coatings with Ta = 14.1, 23.1, 40.7 and 82.9 at.% deposited on 〈1 0 0〉 oriented nickel base single crystal superalloy, TMS-75 were aluminized and subjected to cyclic oxidation at 1373 K, for 600 h. The mass gain as a function of number of cycles data demonstrates an improved oxidation resistance with decreasing Ta content. In contrary to Ta-rich aluminides, Ir-rich aluminides show a large volume fraction of the β-phase, a less amount of γ′-Ni3Al phase near the surface of the coatings. Rapid decrease in the concentration of Al in the diffusion zone and formation of interconnected γ′-Ni3Al has been found to be responsible for the lower oxidation resistance of Ta-rich aluminides.

Original languageEnglish
Pages (from-to)254-261
Number of pages8
JournalMaterials Science and Engineering A
Volume452-453
DOIs
Publication statusPublished - 2007 Apr 15

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Keywords

  • Aluminide
  • Diffusion
  • Iridium
  • Microstructure
  • Oxidation
  • Tantalum

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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