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In materials science, lamellar structures or microstructures are composed of fine, alternating layers of different materials in the form of lamellae. They are often observed in cases where a phase transition front moves quickly, leaving behind two solid products, as in rapid cooling of eutectic (such as solder ) or eutectoid (such as pearlite ...
Lamellae can also describe the layers of atoms in the crystal lattices of materials such as metals. In surface anatomy, a lamella is a thin plate-like structure, often one amongst many lamellae very close to one another, with open space between. In chemical engineering, the term is used for devices such as filters and heat exchangers.
Commonly, in gaps between the lamellae, a fine-grained mixture of kamacite and taenite called plessite can be found. [1] Widmanstätten structures describe analogous features in modern steels, [2] titanium, and zirconium alloys, but are usually microscopic in size.
Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (87.5 wt%) and cementite (12.5 wt%) that occurs in some steels and cast irons. During slow cooling of an iron-carbon alloy, pearlite forms by a eutectoid reaction as austenite cools below 723 °C (1,333 °F) (the eutectoid temperature).
In gaps between the kamacite and taenite lamellae, a fine-grained mixture called plessite is often found. An iron nickel phosphide, schreibersite, is present in most nickel-iron meteorites, as well as an iron-nickel-cobalt carbide, cohenite. Graphite and troilite occur in rounded nodules up to several cm in size. [2]
Lamellae form during crystallization from the melt. The arrow shows the direction of temperature gradient. [5] Nucleation starts with small, nanometer-sized areas, where a result of heat motions in some chains or their segments occur parallel. Those seeds can either dissociate, if thermal motion destroys the molecular order, or grow further, if ...
Lamella (materials), a fine, plate-like structure, usually in a group; Lamellar armour; Lamella clarifier, an inclined-plate clarifier used in water treatment systems; Lamella (structures), used to cover wide, open areas with no supporting members (i.e. arenas, "domes") Musical instrument reed
Principle of lamellae formation during the crystallization of polymers. Arrow shows the direction of temperature gradient. [1]If a molten linear polymer (such as polyethylene) is cooled down rapidly, then the orientation of its molecules, which are randomly aligned, curved and entangled remain frozen and the solid has disordered structure.