On the mechanism of oxidation resistance of W-Cr-Pd alloys

Alon Kafri, Alexandra Makonovitsky, Roni Z. Shneck

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

While studying activation sintering of tungsten, Evans [5] and Ito and Furusawa [6] revealed that W-Cr-Pd alloys exhibit unexpected oxidation resistance at elevated temperatures. The role of palladium in stimulating oxidation resistance in W-Cr alloys is the main aim of the present contribution. As previously observed, at 800°C these alloys form a relatively dense protective scale that consists of an inner layer of Cr2O3, an intermediate layer of Cr2WO6 and an external layer of WO3. At 1200°C only Cr2WO6 layer is found, since the Cr2O3 and WO3 evaporate. To determine the role of paladium, W and W-Pd alloys were coated with Cr layers and undergone diffusion experiments. An extraordinary affinity between the Cr and Pd was revealed, manifested by extremely fast inward diffusion of Cr along grain boundaries. In a second experiment the dissolution of Cr into W grains at 1300oC was followed and found to take place preferentially along grain boundaries. These observations assess that the Pd segregated at grain boundaries provides fast diffusion channels for Cr to the free surface and it imparts the significant improvement of the oxidation resistance of W alloys, as suggested by Lee and Simkovitz [10-12].

Original languageEnglish
Title of host publicationDiffusion in Materials DIMAT-2017 - 10th International Conference on Diffusion in Materials
EditorsEugen Rabkin, Leonid Klinger, Amy Novick-Cohen, Nachum Frage
PublisherTrans Tech Publications Ltd
Pages133-141
Number of pages9
Volume383
ISBN (Print)9783035711301
DOIs
StatePublished - 1 Jan 2018
Event10th International Conference on Diffusion in Materials, DIMAT 2017 - Haifa, Israel
Duration: 7 May 201712 May 2017

Conference

Conference10th International Conference on Diffusion in Materials, DIMAT 2017
Country/TerritoryIsrael
CityHaifa
Period7/05/1712/05/17

Keywords

  • Fast diffusion
  • Oxidation
  • Refractory metals

ASJC Scopus subject areas

  • Radiation
  • Materials Science (all)
  • Condensed Matter Physics

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