Widmannstaetten Structure

(metallography), a variety of metallographie structure of alloys, distinguished by the geometrically regular distribution of structural elements in the form of plates or needles within the crystal grains composing the alloy. The Widmannstaetten structure was first discovered by the English scientist W. Thomson and the Austrian scientist A. Widmannstatten at the beginning of the 19th century while studying iron-nickel meteorites (so-called Widmannstaetten figures). The term“Widmannstaetten structure” was applied to the structural characteristics of greatly superheated or ingot steel, in which the excess ferrite that separates from the austenite is distributed along the octahedral surfaces of the austenite crystals; today the term is used in describing the geometrically ordered structures in alloys. The formation of such structures is explained by the fact that, during secondary crystallization and recrystallization in the solid state, the laminar or acicular shape of the crystals forming the structure and their joining by certain planes with similar atomic structure provide a minimal amount of elastic and surface energy.