Ledeburite

(named for the German metallurgist A. Ledebur [1837–1906]), one of the principal structural constituents of iron-carbon alloys, primarily cast iron. Ledeburite is a eutectic mixture of austenite and cementite that forms at temperatures below 1145°C (for pure iron-carbon alloys). The austenite is converted into a ferrite-cementite mixture at temperatures below 723°C. In steels, ledeburite, consisting of austenite and carbides, is formed only in the presence of a very high content of alloy components and carbon (0.7–1.0 percent); such steels (for example, high-speed steel) are called ledeburite steels.