Intermetallic

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An intermetallic (also called intermetallic compound, intermetallic alloy, ordered intermetallic alloy, long-range-ordered alloy) is a type of metallic alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties.[1][2][3] They can be classified as stoichiometric or nonstoichiometic intermetallic compounds.[1]

Although the term "intermetallic compounds", as it applies to solid phases, has been in use for many years,

species.[4]

Definitions

Research definition

Schulze in 1967[5] defined intermetallic compounds as solid phases containing two or more metallic elements, with optionally one or more non-metallic elements, whose crystal structure differs from that of the other constituents. Under this definition, the following are included:

  1. Electron (or Hume-Rothery) compounds
  2. Size packing phases. e.g. Laves phases, Frank–Kasper phases and Nowotny phases
  3. Zintl phases

The definition of a metal is taken to include:

  1. post-transition metals, i.e. aluminium, gallium, indium, thallium, tin, lead, and bismuth.
  2. metalloids, e.g. silicon, germanium, arsenic, antimony and tellurium.

Homogeneous and heterogeneous

interstitial compounds such as the carbides and nitrides
are excluded under this definition. However, interstitial intermetallic compounds are included, as are alloys of intermetallic compounds with a metal.

Common use

In common use, the research definition, including

stoichiometric, and share similar properties to the intermetallic compounds defined above.[citation needed
]

Complexes

The term intermetallic is used[6] to describe compounds involving two or more metals such as the cyclopentadienyl complex Cp6Ni2Zn4.

B2

A B2 intermetallic compound has equal numbers of atoms of two metals such as aluminium and iron, arranged as two interpenetrating simple cubic lattices of the component metals.[7]

Properties and applications

Intermetallic compounds are generally brittle at room temperature and have high melting points. Cleavage or intergranular fracture modes are typical of intermetallics due to limited independent

titanium alloys. Silicides, inter-metallic involving silicon, are utilized as barrier and contact layers in microelectronics.[9]

Physical properties of intermetallics[1]
Intermetallic Compound Melting Temperature

(°C)

Density

(kg/m3)

Young's Modulus (GPa)
FeAl 1250-1400 5600 263
Ti3Al 1600 4200 210
MoSi2 2020 6310 430

Examples

  1. Magnetic materials e.g. alnico, sendust, Permendur, FeCo, Terfenol-D
  2. niobium-tin
  3. nickel metal hydride batteries
    )
  4. Nitinol
    (NiTi)
  5. Coating materials e.g. NiAl
  6. High-temperature
    structural materials e.g. nickel aluminide
    , Ni3Al
  7. Dental amalgams
    , which are alloys of intermetallics Ag3Sn and Cu3Sn
  8. barrier layer for microelectronics e.g. TiSi2[10]
  9. Laves phases (AB2), e.g., MgCu2, MgZn2 and MgNi2.

The formation of intermetallics can cause problems. For example,

intermetallics of gold and aluminium can be a significant cause of wire bond failures in semiconductor devices and other microelectronics devices. The management of intermetallics is a major issue in the reliability of solder joints between electronic components.[citation needed
]

Intermetallic particles

Main article: Intermetallic particle

Intermetallic particles often form during solidification of metallic alloys, and can be used as a dispersion strengthening mechanism.[1]

History

Examples of intermetallics through history include:

  1. Roman yellow brass, CuZn
  2. Chinese high tin bronze, Cu31Sn8
  3. Type metal, SbSn
  4. Chinese white copper, CuNi [11]

German type metal is described as breaking like glass, not bending, softer than copper but more fusible than lead.[12] The chemical formula does not agree with the one above; however, the properties match with an intermetallic compound or an alloy of one.[citation needed]

See also

References

  • Gerhard Sauthoff: Intermetallics, Wiley-VCH, Weinheim 1995, 165 pages
  • Intermetallics, Gerhard Sauthoff, Ullmann's Encyclopedia of Industrial Chemistry, Wiley Interscience. (Subscription required)
  1. ^
    OCLC 903959750.{{cite book}}: CS1 maint: location missing publisher (link
    )
  2. OCLC 906692179
    .
  3. OCLC 300921090
    .
  4. ^ Hume-Rothery, W. (1955) [1948]. Electrons, atoms, metals and alloys (revised ed.). London: Louis Cassier Co., Ltd. pp. 316–317 – via the Internet Archive.
  5. ^ G. E. R. Schulze: Metallphysik, Akademie-Verlag, Berlin 1967
  6. ISBN 0-471-19957-5
  7. ^ "Wings of steel: An alloy of iron and aluminium is as good as titanium, at a tenth of the cost". The Economist. February 7, 2015. Retrieved February 5, 2015. E02715
  8. OCLC 300921090
    .
  9. ^ S.P. Murarka, Metallization Theory and Practice for VLSI and ULSI. Butterworth-Heinemann, Boston, 1993.
  10. ^ Milton Ohring, Materials Science of Thin Films, 2nd Edition, Academic Press, San Diego, CA, 2002, p. 692.
  11. ^ "The Art of War by Sun Zi: A Book for All Times". China Today. Archived from the original on 2005-03-07. Retrieved 2022-11-25.
  12. ^ [1] Type-pounding The Penny Cyclopædia of the Society for the Diffusion of Useful Knowledge By Society for the Diffusion of Useful Knowledge (Great Britain), George Long Published 1843

External links

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