What is eutectic temperature

An alloy or solution is made eutectic (Greek: ευ = good τεκτειν = to build) when their components are in such a relationship that they become liquid or solid as a whole at a certain temperature (melting point). The corresponding point in the phase diagram is called Eutectic (Plural: eutectics).

Other mixing ratios have a melting or solidification range in which, in addition to the melt, there is also a solid phase. The liquidus temperature characterizes the complete liquefaction, the solidus temperature the complete solidification of the alloy.

A eutectic has the lowest melting point of any mixture of the same ingredients. When solidifying, all components separate in very fine crystals at the same time, creating a fine and even structure, usually with a characteristic lamellar structure.

Examples of eutectics are the Sn-Pb system ("solder") z. B. with a composition of 62/38, the Ag-Cu (silver-copper alloy) system with a composition of 72/28, Rose's metal, Wood's metal, certain quartz porphyries or a solution of 30.9 g of table salt to 100 g of water. These easily melting alloys are used in sprinkler systems, as soldering alloys or in joke articles. Mercury-free analog clinical thermometers contain a eutectic, e.g. B. from gallium, indium and tin, known as Galinstan.

A eutectic system denotes a Multi-substance systemwhere a eutectic can occur. The prerequisite for this is a melting temperature of the mixing system below the melting temperature of the individual components and a miscibility gap in the solid that remains until the melting temperature of the eutectic is reached.

The eutectic point denotes one in the phase diagram Multi-fuel system the point which is determined by the concentration ratio of the eutectic and by its melting temperature (eutectic temperature) is marked.

See also

Peritectic, monotectic, binary systems with complete insolubility in the solid state

Categories: Alloy | Materials science