Iron–nickel alloy

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"NiFe" redirects here. For the battery, see Nickel–iron battery. For the cutting tool, see knife.

An iron–nickel alloy, nickel–iron alloy, or abbreviated FeNi and NiFe, is a group of alloys that mostly consist of the elements nickel (Ni) and iron (Fe). The acronym NiFe is used to refer to various chemical reactions that involve a nickel–iron catalyst or component, or in geology, to refer to the general composition of planetary cores (including Earth's).

Astronomy and geology[edit]

Iron and nickel are notable for being the final elements produced by stellar nucleosynthesis, and thus the heaviest elements that do not require a supernova or similarly cataclysmic event for formation.[1] Iron and nickel are therefore the most abundant metals in metallic meteorites[2] and in the dense-metal cores of planets such as Earth.

Nickel–iron alloys occur naturally on Earth as telluric or meteoric iron.

Chemistry and technology[edit]

The affinity of nickel (atomic number 28) and iron (atomic number 26) for one another produce natural occurring alloys, a large number of commercial alloys, and provide a complex electron environment for catalyzing chemical reactions.[3]

In steel technology nickel is alloyed with iron to produce maraging steel and some low-alloy steels. Other technological uses include Invar and Mu-metal.


The following table is an overview of different iron–nickel alloys. Naturally occurring alloys are a type of mineral and called native elements or native metals. Some of the entries have more than one crystal structure (e.g. meteoric iron is a mixture of two crystal structures).

Name Description Chemical formula/Weight percent Ni
Antitaenite A native metal found in meteorites. Fe3Ni[4]
Austenite A special allotrope of steel that is stabilized with nickel.
Awaruite A native metal found in serpentinites and meteorites. Ni2Fe to Ni3Fe
Earth's core Earth's core is composed of an iron–nickel alloy. about 5.5%[5]
Elinvar A steel whose elasticity does not change with temperature. 36% (also 5% chromium)
Invar A steel with very low thermal expansion. 36%
Kamacite A native metal found in meteoric iron Fe0.9Ni0.1
Maraging steel A strong, malleable variant of steel 15 to 25%
Meteoric iron A combination of mostly kamacite and taenite and minor amounts of tetrataenite, antitaenite and awaruite. 5–30%
Mu-metal A metal with high magnetic permeability. 77%
Planetary core Planets, Moons and Planetesimals also can have cores made of an iron–nickel alloy. Various
Taenite A native metal found in meteorites NiFe
Telluric iron A native metal found on earth (not extraterrestrial) Fe (but 0.05 to 4% nickel)
Tetrataenite A native metal found in meteorites. FeNi

See also[edit]


  1. ^ Wannier, P G (1980). "Nuclear Abundances and Evolution of the Interstellar Medium". Annual Review of Astronomy and Astrophysics 18: 399. Bibcode:1980ARA&A..18..399W. doi:10.1146/annurev.aa.18.090180.002151. 
  2. ^ Mason, Brian Harold (1971) Handbook of Elemental Abundances in Meteorites Gordon and Breach, New York, ISBN 0-677-14950-6
  3. ^ Pardo, A; De Lacey, AL; Fernández, VM; Fan, HJ; Fan, Y; Hall, MB (2006). "Density functional study of the catalytic cycle of nickel-iron NiFe hydrogenases and the involvement of high-spin nickel(II)". Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry 11 (3): 286–306. doi:10.1007/s00775-005-0076-3. PMID 16511689. 
  4. ^ "Mindat Antitaenite". Mindat. Retrieved 9 January 2013. 
  5. ^ Lin, Jung-Fu (1 January 2002). "Iron-Nickel alloy in the Earth's core". Geophysical Research Letters 29 (10). Bibcode:2002GeoRL..29.1471L. doi:10.1029/2002GL015089.