Rapid solidification and metastable phase formation during surface modifications of composite Al-Cr cathodes exposed to cathodic arc plasma

Research output: Contribution to journalArticleResearchpeer-review

External Organisational units

  • Erich Schmid Institute of Materials Science
  • Plansee Composite Materials GmbH

Abstract

A combination of both conventional and advanced high-resolution characterization techniques was applied to study the modified layers on the surface of three composite Al-Cr arc cathodes with identical nominal composition of Al-50 at.% Cr but varying powder grain sizes. The results revealed that the modified layers consist mainly of metastable phases such as Cr solid solution, high temperature cubic Al 8Cr 5, supersaturated Al solid solution, and icosahedral quasicrystal. The metastable phase formation indicates that high cooling rates were involved during the solidification of molten material produced in the arc craters during cathode spot events. The average cooling rate was estimated to be 10 6 K/s based on secondary dendrite arm spacing measurements and supporting phase-field based simulations. The formation mechanisms of the modified layers are discussed based on the obtained results and the current literature.

Details

Original languageEnglish
Pages (from-to)147-163
Number of pages17
JournalJOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
Volume94:2021
Issue number20 December
Early online date18 May 2021
DOIs
Publication statusE-pub ahead of print - 18 May 2021