Definition of "cementite" []

• A hard brittle iron carbide, Fe3C, found in steel with more than 0.85 percent carbon. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "However, upon cooling this steel, the carbon again enters into combination with a definite proportion of iron (the carbide "cementite," Fe3C), and accumulates into small crystals which can be seen under a good microscope."
• "The carbon absorbed by the iron does not take on a graphitic form, however, as in the case of cast iron, but enters into a chemical compound with the iron, a hard brittle substance called "cementite" by metallurgists."
• "The ferrite _i. e._, the iron is increased in strength by the resistance offered by the cementite which is the simple iron-carbon combination known to metallurgists as Fe3C."