Cementite or iron carbide is a chemical compound with the formula Fe₃C, and an orthorhombic crystal structure. It is a hard, brittle material, normally classified as a ceramic in its pure form, though it is more important in metallurgy. General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... In crystallography, the orthorhombic crystal system is one of the 7 lattice point groups. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ... Metallurgy is a domain of materials science and of materials engineering that studies the physical and chemical behavior of metallic elements and their mixtures, which are called alloys. ...

It forms directly from the melt in the case of white cast iron. In carbon steel, it either forms from austenite during cooling or from martensite during tempering. It mixes with ferrite, the other product of austenite, to form lamellar structures called pearlite and bainite. Much larger lamellae, visible to the naked eye, make up the structure of Damascus steel, though the process has been lost to history. Cast iron usually refers to grey cast iron, but can mean any of a group of iron-based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ... // Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Austenite is a solid solution of carbon and iron that exists in steel above the critical temperature of 1333°F (about 723°C). ... Martensite, named after the German metallurgist Adolf Martens, is a class of hard minerals occurring as lathe- or plate-shaped crystals. ... Tempering is a heat treatment technique for metals and alloys, most often the toughening of martensitic steel. ... Iron-carbon phase diagram, showing the conditions under which ferrite (α) is stable. ... Lamellar structures are gill-shaped structures, with sheets of one material interleaved with another. ... Pearlite is a two-phased, lamellar structure composed of alternating layers of ferrite (88 wt%) and cementite (12%) that occurs in steel. ... Iron-carbon phase diagram, showing the eutectoid temperature and composition, at which bainite can form. ... Damascus steel, also known as Damascened steel, is a type of steel alloy that is both strong and malleable, a material that is perfect for the building of swords. ...

Fe₃C is also known as cohenite, particularly when found mixed with nickel and cobalt carbides in meteorites. This form, a hard, shiny silver mineral, was first described by E. Weinschenk in 1889. General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic Atomic mass 58. ... This article is on the periodic element. ... Bacubirito in Culiacan, Mexico is the second largest meteorite in the Americas, and fifth largest in the world A meteorite is a small extraterrestrial body that reaches the Earths surface. ... 1889 was a common year starting on Tuesday (see link for calendar). ...

Crystal Structure of Cementite, Cambridge University