Iron–nickel alloy

An iron–nickel alloy or nickel–iron alloy, abbreviated FeNi or NiFe, is a group of alloys consisting primarily of the elements nickel (Ni) and iron (Fe). It is the main constituent of the "iron" planetary cores and iron meteorites. The acronym NiFe refers to various chemical reactions that involve an iron–nickel catalyst or component, or in geology, to the general composition of planetary cores (including Earth's).

Widmanstätten pattern in NiFe octahedrite meteorite

Some iron–nickel alloys are called nickel steel and usually contain additional elements, depending on the purpose.