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Oxidation of Metals

, Volume 26, Issue 5–6, pp 363–384 | Cite as

High-temperature oxidation of a rapidly solidified amorphous Ta-Ir alloy

  • Catherine M. Cotell
  • Gregory J. Yurek
Article

Abstract

The oxidation products formed at 500 and 700°C on an amorphous Ta-44.5 at% Ir alloy in an Ar-0.1% O2 gas mixture were characterized using SEM, XRD, EPMA, TEM, STEM, AES, and XPS. Initially, a thin (3–4 nm) layer of Ta2O5 formed at the surface of the alloy. Continued growth of the Ta2O5, which occurred very rapidly, involved diffusion of oxygen anions from the Ta2O5/gas interface to the alloy/Ta2O5 interface, where tantalum was selectively oxidized. Because the oxide grew more quickly than iridium could diffuse back into the alloy, the iridium coalesced into platelets of crystalline iridium-rich alloy that were oriented approximately parallel to the oxide/alloy interface, and which became embedded in a matrix of Ta2O5. The unoxidized core remained in the glassy state. The oxidation process and/or the dissolution of oxygen into the unoxidized alloy caused the alloy to become embrittled.

Key words

high-temperature oxidation metallic glasses amorphous alloys tantalum iridium 

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Copyright information

© Plenum Publishing Corporation 1986

Authors and Affiliations

  • Catherine M. Cotell
    • 1
  • Gregory J. Yurek
    • 1
  1. 1.H. H. Uhlig Corrosion LaboratoryMassachusetts Institute of TechnologyCambridge

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