Glossary

Ledeburite is a hard, brittle microstructural phase found in iron–carbon alloys, specifically cast irons, that forms when the alloy solidifies at the eutectic composition—about 4.3% carbon—at around 1147°C (2097°F). It is named after metallurgist Adolf Ledebur, who first described it.

Ledeburite is not a single substance but a eutectic mixture of two phases:

- Austenite (γ-iron)

- Cementite (Fe₃C), also known as iron carbide

When the alloy cools further, the austenite usually transforms into pearlite (a ferrite–cementite lamellar structure), leaving behind a final room-temperature microstructure that consists of pearlite + cementite. Because cementite is extremely hard and brittle, regions of ledeburite give cast iron very high hardness and abrasion resistance but also low ductility.

Key characteristics of ledeburite:

- Forms only during solidification at eutectic carbon levels in iron–carbon alloys.

- Appears as a white, feathery or network-like structure under a microscope.

- Indicates the material is in the category of white cast iron, which fractures with a white, crystalline surface due to the presence of cementite instead of graphite.

- Contributes to excellent wear and erosion resistance, making white irons useful for grinding media, slurry pumps, liners, and abrasion-intensive applications.