Complex metallic alloys (CMAs) are intermetallic

Intermetallics

Intermetallics or intermetallic compounds is a term that is used in a number of different ways. Most commonly it refers to solid-state phases involving metals. There is a "research definition" adhered to generally in scientific publications, and a wider "common use" term...

 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
   Cluster (physics)
   In physics, the term clusters denotes small, multiatom particles. As a rule of thumb, any particle of somewhere between 3 and 3x107 atoms is considered a cluster. Two-atom particles are sometimes considered clusters as well....
   
   , frequently of icosahedral point group
   Point group
   In geometry, a point group is a group of geometric symmetries that keep at least one point fixed. Point groups can exist in a Euclidean space with any dimension, and every point group in dimension d is a subgroup of the orthogonal group O...
   
    symmetry
   Symmetry
   Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...
   
   ,
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.

Since 2005, the European Commission

European Commission

The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....

 is funding the Network of Excellence CMA http://www.cma-ecnoe.org/, which unites 19 core groups in 12 countries.

Examples

Example phases

Phase (matter)

In the physical sciences, a phase is a region of space , throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, and chemical composition...

 are:

• β-Al
  Aluminium
  Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
  
  -Mg
  Magnesium
  Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
  
  : 1168 atoms per unit cell, face centred cubic
  Cubic crystal system
  In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals....
  
  , atoms arranged in Friauf polyhedra
  Polyhedron
  In elementary geometry a polyhedron is a geometric solid in three dimensions with flat faces and straight edges...
  
  .

• ξ'-Al-Pd
  Palladium
  Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
  
  -Mn
  Manganese
  Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
  
  : 318 atoms per unit cell, face centred orthorhombic
  Orthorhombic crystal system
  In crystallography, the orthorhombic crystal system is one of the seven lattice point groups. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a rectangular base and height , such that a,...
  
  , atoms arranged in Mackay-type clusters.

• T-Mg-Al-Zn
  Zinc
  Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
  
  (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.