Paper Title:
Ti-Al-Cr Based Coatings for High Temperature Oxidation Protection of γ-TiAl
  Abstract

In this study the oxidation resistance of Ti-45Al-8Nb (at.%) alloy coated with quaternary Ti-Al-Cr-X layers (X = Si, Hf, Y, Zr and W) was investigated. The Ti-Al-Cr-Si, Ti-Al-Cr-Hf and Ti-Al-Cr-Y coated specimens were exposed to air at 950°C under cyclic conditions, whereas the samples with Ti-Al-Cr-Zr and Ti-Al-Cr-W coatings were thermally cycled at 1000°C. After the maximum exposure time period of 1000 1h-cycles or failure cross-sections of the samples were examined by means of SEM and EDS to analyse the microstructural evolution. At initial stages of exposure, all intermetallic layers formed a thin alumina layer on top, providing a diffusion barrier to oxygen. But interdiffusion between coating and substrate caused depletion of the Ti(Cr,Al)2 Laves phase in the intermetallic layers, which promoted the formation of alumina, as well as transformation into Ti-rich B2-phase. Coarsening of the latter phase beneath the alumina scale resulted in a higher oxidation resistance compared to that of ternary Ti-Al-Cr coating.

  Info
Periodical
Materials Science Forum (Volumes 638-642)
Main Theme
Edited by
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
Pages
1306-1311
DOI
10.4028/www.scientific.net/MSF.638-642.1306
Citation
M. Fröhlich, R. Braun, C. Leyens, "Ti-Al-Cr Based Coatings for High Temperature Oxidation Protection of γ-TiAl", Materials Science Forum, Vols. 638-642, pp. 1306-1311, 2010
Online since
January 2010
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