Complex metallic alloys

Complex metallic alloys (CMAs) of complex intermetallics (CIMs) are intermetallic compounds characterized by the following structural features:

  1. large unit cells, comprising some tens up to thousands of atoms,
  2. the presence of well-defined atom clusters, frequently of icosahedral point group symmetry,
  3. the occurrence of inherent disorder in the ideal structure.

Research

Most physical properties of CMAs show distinct differences with respect to the behaviour of normal metallic alloys and therefore these materials possess a high potential for technological application.

The European Commission funded the Network of Excellence CMA from 2005 to 2010, uniting 19 core groups in 12 countries. From this emerged the European Integrated Center for the Development of New Metallic Alloys and Compounds C-MAC , which connects researchers at 21 universities.

Examples

Example phases are:

  • β-Al–Mg: 1168 atoms per unit cell, face centred cubic, atoms arranged in Friauf polyhedra.
  • ξ'–Al–Pd–Mn: 318 atoms per unit cell, face centred orthorhombic, atoms arranged in Mackay-type clusters.
  • T–Mg–Al–Zn (Bergman phase): 163 atoms per unit cell, body centred cubic, atoms arranged in Bergman clusters.
  • T–Al3Mn (Taylor phase): 204 atoms per unit cell, face centred orthorohombic, atoms arranged in Mackay-type clusters.

Further reading

  • Urban, Knut; Feuerbacher, Michael. "Structurally complex alloy phases". Journal of Non-Crystalline Solids. Elsevier B.V. 334–335: 143–150. Bibcode:2004JNCS..334..143U. doi:10.1016/j.jnoncrysol.2003.11.029.
  • Dubois, Jean-Marie; Belin-Ferré, Esther, eds. (2011). Complex Metallic Alloys: Fundamentals and Applications. Wiley-VCH. doi:10.1002/9783527632718. ISBN 978-3-527-32523-8.
  1. EC Network of Excellence Complex Metallic Alloys
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