Editing Eutectic system (section)

==Types==

===Alloys===
Eutectic [[alloy]]s have two or more materials and have a eutectic composition. When a non-eutectic alloy solidifies, its components solidify at different temperatures, exhibiting a plastic melting range. Conversely, when a well-mixed, eutectic alloy melts, it does so at a single, sharp temperature. The various phase transformations that occur during the solidification of a particular alloy composition can be understood by drawing a vertical line from the liquid phase to the solid phase on the phase diagram for that alloy.

Some uses for eutectic alloys include:
*NEMA eutectic alloy overload relays for [[power-system protection|electrical protection]] of three-phase motors for pumps, fans, conveyors, and other factory process equipment.<ref>{{cite web |url= http://www.industrial-electronics.com/output_devices_amplifiers_valves_relays_variable-frequency_drives_stepper_motors_servomotors/Operation_Overloads.html |title= Operation of the Overloads |access-date= 2015-08-05 }}</ref>
*Eutectic alloys for [[soldering]], both traditional alloys composed of [[lead]] (Pb) and [[tin]] (Sn), sometimes with additional [[silver]] (Ag) or [[gold]] (Au) — especially [[Solder alloys#Sn63Pb37|Sn{{sub|63}}Pb{{sub|37}}]] and Sn{{sub|62}}Pb{{sub|36}}Ag{{sub|2}} alloy formula for electronics - and newer lead-free soldering alloys, in particular ones composed of tin, silver, and [[copper]] (Cu) such as Sn{{sub|96.5}}Ag{{sub|3.5}}.
*Casting alloys, such as [[Silumin|aluminium-silicon]] and [[cast iron]] (at the composition of 4.3% carbon in iron producing an [[austenite]]-[[cementite]] eutectic)
*[[Silicon chip]]s are [[eutectic bonding|eutectic bonded]] to gold-plated substrates through a silicon-gold eutectic by the application of [[ultrasound|ultrasonic]] energy to the chip. 
*[[Brazing]], where diffusion can remove alloying elements from the joint, so that eutectic melting is only possible early in the brazing process
*Temperature response, e.g., [[Wood's metal]] and [[Field's metal]] for [[fire sprinkler]]s
*Non-toxic [[Mercury (element)|mercury]] replacements, such as [[galinstan]]
*Experimental [[amorphous metal|glassy metals]], with extremely high strength and [[corrosion]] resistance
*Eutectic alloys of [[sodium]] and [[potassium]] ([[NaK]]) that are liquid at room temperature and used as [[coolant]] in experimental [[Fast neutron reactor|fast neutron nuclear reactor]]s.

===Others===
[[File:Phase diagram ethanol water s l en.svg|thumb|upright=1.3|Solid–liquid phase change of ethanol–water mixtures]]
* [[Sodium chloride]] and [[water]] form a eutectic mixture whose eutectic point is −21.2&nbsp;°C<ref>{{cite web | last = Muldrew | first = Ken | author2 = Locksley E. McGann | year = 1997 | url = https://www.ucalgary.ca/~kmuldrew/cryo_course/cryo_chap6_1.html | title = Phase Diagrams | work = Cryobiology—A Short Course | publisher = University of Calgary | access-date = 2006-04-29 | archive-url = https://web.archive.org/web/20060615124330/http://www.ucalgary.ca/~kmuldrew/cryo_course/cryo_chap6_1.html | archive-date = 2006-06-15 | url-status = dead }}</ref> and 23.3% salt by mass.<ref>{{cite web | last = Senese | first = Fred | year = 1999 | url = http://antoine.frostburg.edu/chem/senese/101/solutions/faq/saltwater-ice-volume.shtml | title = Does salt water expand as much as fresh water does when it freezes? | work = Solutions: Frequently asked questions | publisher = Department of Chemistry, Frostburg State University | access-date = 2006-04-29}}</ref> The eutectic nature of salt and water is exploited when salt is spread on roads to aid [[snow removal]], or mixed with ice to produce low temperatures (for example, in traditional [[ice cream]] making).
* Ethanol–water has an unusually biased eutectic point, i.e. it is close to pure ethanol, which sets the maximum proof obtainable by [[fractional freezing]]. 
* "Solar salt", 60% NaNO<sub>3</sub> and 40% KNO<sub>3</sub>, forms a eutectic molten salt mixture which is used for [[thermal energy storage]] in [[concentrated solar power]] plants.<ref>{{cite web |title=Molten salts properties |url=http://www.archimedesolarenergy.com/molten_salt.htm |work=Archimede Solar Plant Specs |access-date=2011-07-15 |archive-date=2020-04-20 |archive-url=https://web.archive.org/web/20200420183555/http://www.archimedesolarenergy.com/molten_salt.htm |url-status=dead }}</ref> To reduce the eutectic melting point in the solar molten salts, [[calcium nitrate]] is used in the following proportion: 42% Ca(NO<sub>3</sub>)<sub>2</sub>, 43% KNO<sub>3,</sub> and 15% NaNO<sub>3</sub>.
* [[Lidocaine]] and [[prilocaine]]—both are solids at room temperature—form a eutectic that is an oil with a {{convert|16|C|abbr=on}} melting point that is used in [[eutectic mixture of local anesthetic]] (EMLA) preparations.
* [[Menthol]] and [[camphor]], both solids at room temperature, form a eutectic that is a liquid at room temperature in the following proportions: 8:2, 7:3, 6:4, and 5:5. Both substances are common ingredients in pharmacy extemporaneous preparations.<ref>{{Cite journal |last1=Phaechamud |first1=Thawatchai |last2=Tuntarawongsa |first2=Sarun |last3=Charoensuksai |first3=Purin |date=October 2016 |title=Evaporation Behavior and Characterization of Eutectic Solvent and Ibuprofen Eutectic Solution |journal=AAPS PharmSciTech |volume=17 |issue=5 |pages=1213–1220 |doi=10.1208/s12249-015-0459-x |issn=1530-9932 |pmid=26669887|doi-access=free }}</ref>
* [[Mineral]]s may form eutectic mixtures in [[igneous]] rocks, giving rise to characteristic [[Rock microstructure#Graphic and other intergrowth textures|intergrowth textures]] exhibited, for example, by [[granophyre]].<ref>{{cite web | last = Fichter | first = Lynn S. | year = 2000 | url = http://csmres.jmu.edu/geollab/Fichter/IgnRx/Phasdgrm.html | title = Igneous Phase Diagrams | work = Igneous Rocks | publisher = James Madison University | access-date = 2006-04-29 | archive-date = 2011-06-28 | archive-url = https://web.archive.org/web/20110628195112/http://csmres.jmu.edu/geollab/Fichter/IgnRx/Phasdgrm.html | url-status = dead }}</ref>
* Some inks are eutectic mixtures, allowing [[inkjet printer]]s to operate at lower temperatures.<ref>{{cite patent |country=US |number=5298062A |title=Eutectic compositions for hot melt jet inks |pubdate=1994-03-29 |gdate=1994-03-29 |fdate=1992-08-19 |pridate=1992-08-19 |inventor1-last=Davies |inventor1-first=Nicholas A. |inventor2-last=Nicholas |inventor2-first=Beatrice M.}}</ref>
* [[Choline]] chloride produces eutectic mixtures with many natural products such as [[citric acid]], [[malic acid]] and [[sugars]]. These liquid mixtures can be used, for example, to obtain antioxidant and antidiabetic extracts from [[natural product]]s.<ref>{{Cite journal |last1=Socas-Rodriguez |first1=Bárbara |last2=Torres-Cornejo |first2=Mónica Vanesa |last3=Álvarez-Rivera |first3=Gerardo |last4=Mendiola |first4=Jose A. |date=May 2021 |title=Deep Eutectic Solvents for the Extraction of Bioactive Compounds from Natural Sources and Agricultural By-Products |journal=Applied Sciences  |volume=11 |issue=1 |pages=4897 |doi=10.3390/app11114897 |issn=2076-3417 |doi-access=free |hdl=10261/253199 |hdl-access=free }}</ref>