BackgroundMicrostructure refers to the arrangement of atoms in an ordered, repeating three-dimensional pattern. The microstructure of a metal is closely related to its quality, composition, processing history and properties. Metals are generally polycrystalline and composed of many grains. The grains are usually invisible and therefore require a microscope to see clearly. Apart from the grain boundaries, the crystal structure of the material remains the same. Microstructures are characterized by the arrangement, their proportions and the number of phases present. For alloys, their microstructures also depend on the composition of the alloy, the concentration of the components and the heat treatment of the alloy. Eutectic structures are characterized by alternating layers. For ferrocarbon alloys, common microstructures can be pearlite, spheroidite, bainite and martensite and are composed of varying amounts of ferrite and cementite. Ferrite has a BCC crystal structure and is the stable form of iron. Cementite is the intermediate compound that forms at 6.7 ...