Metallurgical Transactions A

, Volume 17, Issue 12, pp 2117–2125 | Cite as

Icosahedral and decagonal phase formation in Al-Mn alloys

  • R. J. Schaefer
  • L. A. Bendersky
  • D. Shechtman
  • W. J. Boettinger
  • F. S. Biancaniello
Alloy Phases

Abstract

The solidification conditions leading to the formation of the icosahedral phase in Al-Mn alloys have been investigated, using samples prepared by melt spinning and electron beam surface melting. It is found that the icosahedral phase can grow with a range of compositions, but that it grows in competition with another metastable phase which is decagonal. Both of these phases can displace the equilibrium intermetallic phases by nucleating ahead of them in the melt when the solidification velocity is greater than a few centimeters per second. The relative abundance of the icosahedral and decagonal phases varies with composition and solidification rate. Icosahedral crystals in electron beam melt trails are often about 25 μm in diameter, and they grow dendritically along a preferred crystallographic direction.

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Copyright information

© The Metallurgical of Society of AIME 1986

Authors and Affiliations

  • R. J. Schaefer
    • 1
  • L. A. Bendersky
    • 2
  • D. Shechtman
    • 3
    • 4
  • W. J. Boettinger
    • 1
  • F. S. Biancaniello
    • 1
  1. 1.Metallurgy DivisionNational Bureau of StandardsGaithersburg
  2. 2.Center for Materials Science, The Johns Hopkins UniversityBaltimore
  3. 3.Department of Materials EngineeringTechnionHaifaIsrael
  4. 4.Center for Materials Science, The Johns Hopkins UniversityBaltimore

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