An iron–nickel alloy or nickel–iron alloy, abbreviated FeNi or NiFe, is a group of

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductilit ...

s consisting primarily of the elements

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

(Ni) and

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

(Fe). It is the main constituent of the "iron" planetary cores and

iron meteorite Iron meteorites, also known as siderites, or ferrous meteorites, are a type of meteorite that consist overwhelmingly of an iron–nickel alloy known as meteoric iron that usually consists of two mineral phases: kamacite and taenite. Most iron ...

s. In chemistry, the acronym NiFe refers to an iron–nickel

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

or component involved in various

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

s, or the reactions themselves; in

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...

, it refers to the main constituents of telluric planetary cores (including Earth's). Some manufactured alloys of iron–nickel are called ''nickel steel'' or '' stainless steel''. Depending on the intended use of the alloy, these are usually fortified with small amounts of other metals, such as chromium,

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

, molybdenum, and

titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...

Astronomy and geology

Iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

and

are the most abundant elements produced during the final stage of stellar nucleosynthesis in massive stars. Heavier elements require other forms of

nucleosynthesis Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons (protons and neutrons) and nuclei. According to current theories, the first nuclei were formed a few minutes after the Big Bang, through nuclear reactions in ...

, such as during a supernova or

neutron star merger A neutron star merger is a type of stellar collision. It occurs in a fashion similar to the rare brand of type Ia supernovae resulting from merging white dwarf stars. When two neutron stars orbit each other closely, they gradually spiral i ...

. Iron and nickel are the most abundant metals in metallic meteorites and in the dense metal cores of telluric planets, such as Earth. Nickel–iron alloys occur naturally on Earth's surface as

telluric iron Telluric iron, also called native iron, is iron that originated on Earth, and is found in a metallic form rather than as an ore. Telluric iron is extremely rare, with only one known major deposit in the world, located in Greenland. Introduction W ...

meteoric iron Meteoric iron, sometimes meteoritic iron, is a native metal and early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric ir ...

Chemistry and metallurgy

The affinity of nickel atoms (

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

28) for iron (atomic number 26) results in natural occurring

s and a large number of commercial alloys. The surfaces of these metallic compounds provide a complex electron environment for catalyzing chemical reactions. In steel metallurgy, nickel is alloyed with iron to produce

maraging steel Maraging steels (a portmanteau of " martensitic" and "aging") are steels that are known for possessing superior strength and toughness without losing ductility. ''Aging'' refers to the extended heat-treatment process. These steels are a special cla ...

and some low-alloy steels. Other technological uses include

Invar Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name ''Invar'' comes from the word ''invariable'', referring to its relative lac ...

and Mu-metal.

Alloy summary

The following table is an overview of different iron–nickel alloys. Naturally occurring

s are a type of

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

and called native elements or native metals. Some of the entries have more than one crystal structure (e.g.

is a mixture of two crystal structures).

References

{{DEFAULTSORT:Iron-nickel alloy Petrology Structure of the Earth Ferrous alloys Meteorites

Astronomy and geology

Chemistry and metallurgy

Alloy summary

See also

References