cementite n : the iron carbide constituent of steel and cast iron; very hard and brittle [syn: iron carbide]
Cementite or iron carbide is a chemical compound with the formula Fe3C (or Fe2C:Fe), 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.
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.
Fe3C is also known as cohenite, particularly when found mixed with nickel and cobalt carbides in meteorites. This forms a hard, shiny, silver mineral which was first described by E. Weinschenk in 1889.
cementite in Bosnian: Cementit
cementite in Czech: Karbid železa
cementite in German: Zementit
cementite in Estonian: Tsementiit
cementite in Modern Greek (1453-): Σεμεντίτης
cementite in Spanish: Cementita
cementite in Persian: سمنتیت
cementite in French: Cémentite
cementite in Galician: Cementita
cementite in Italian: Cementite
cementite in Hungarian: Cementit
cementite in Dutch: Cementiet
cementite in Japanese: セメンタイト
cementite in Polish: Cementyt
cementite in Portuguese: Cementita
cementite in Romanian: Cementită
cementite in Russian: Цементит
cementite in Slovak: Cementit
cementite in Serbian: Цементит
cementite in Chinese: 碳化三铁