Editing Metal (section)

==Alloys==
{{Main|Alloy}}
[[File:Pigs and Bars of Babbitt.jpg|thumb|left|Samples of [[babbitt (alloy)|babbitt metal]], an alloy of [[tin]], [[antimony]], and [[copper]], used in bearings to reduce friction|alt=Three bars of babbitt metal]]

In the context of metals, an alloy is a substance having metallic properties which is composed of two or more [[chemical element|elements]]. Often at least one of these is a metallic element; the term "alloy" is sometimes used more generally as in [[silicon–germanium]] alloys. An alloy may have a variable or fixed composition. For example, gold and silver form an alloy in which the proportions of gold or silver can be varied; titanium and silicon form an alloy [[Titanium disilicide|TiSi<sub>2</sub>]] in which the ratio of the two components is fixed (also known as an [[intermetallic compound]]<ref>{{Cite journal |last1=Liu |first1=C. T. |last2=Stiegler |first2=J. O. |date=1984-11-09 |title=Ductile Ordered Intermetallic Alloys |url=https://www.science.org/doi/10.1126/science.226.4675.636 |journal=Science |language=en |volume=226 |issue=4675 |pages=636–642 |doi=10.1126/science.226.4675.636 |pmid=17774926 |bibcode=1984Sci...226..636L |issn=0036-8075}}</ref><ref>{{Cite journal |last1=Cinca |first1=Nuria |last2=Lima |first2=Carlos Roberto Camello |last3=Guilemany |first3=Jose Maria |date=2013 |title=An overview of intermetallics research and application: Status of thermal spray coatings |journal=Journal of Materials Research and Technology |volume=2 |issue=1 |pages=75–86 |doi=10.1016/j.jmrt.2013.03.013 |issn=2238-7854|doi-access=free }}</ref>).

[[File:Willem Lenssinck - Formula I Racing Horse.jpg|thumb|150px|A sculpture cast in [[nickel silver]]—an alloy of copper, nickel, and zinc that looks like silver|alt=A metal sculpture]]
Most pure metals are either too soft, brittle, or chemically reactive for practical use. Combining different ratios of metals and other elements in alloys modifies the properties to produce desirable characteristics, for instance more ductile, harder, resistant to corrosion, or have a more desirable color and luster. Of all the metallic alloys in use today, the alloys of [[iron]] ([[steel]], [[stainless steel]], [[cast iron]], [[tool steel]], [[alloy steel]]) make up the largest proportion both by quantity and commercial value.<ref>{{Cite web |title=Steel use by sector |url=https://worldsteel.org/data/steel-use-by-sector/ |access-date=2024-09-18 |website=worldsteel.org |language=en-US}}</ref> Iron alloyed with various proportions of carbon gives low-, mid-, and high-carbon steels, with increasing carbon levels reducing ductility and toughness. The addition of [[silicon]] will produce cast irons, while the addition of [[chromium]], [[nickel]], and [[molybdenum]] to carbon steels (more than 10%) results in stainless steels with enhanced corrosion resistance.

Other significant metallic alloys are those of [[aluminium]], [[titanium]], [[copper]], and [[magnesium]]. Copper alloys have been known since prehistory—[[bronze]] gave the [[Bronze Age]] its name—and have many applications today, most importantly in electrical wiring. The alloys of the other three metals have been developed relatively recently; due to their chemical reactivity they need [[electrolysis|electrolytic]] extraction processes. The alloys of aluminium, titanium, and magnesium are valued for their high strength-to-weight ratios; magnesium can also provide [[electromagnetic shielding]].<ref>{{Cite journal |date=December 17, 2020 |title=Electromagnetic Shielding Performance of Different Metallic Coatings Deposited by Arc Thermal Spray Process |pmc=7767199 |last1=Jang |first1=J. M. |last2=Lee |first2=H. S. |last3=Singh |first3=J. K. |journal=Materials |volume=13 |issue=24 |page=5776 |doi=10.3390/ma13245776 |doi-access=free |pmid=33348891 |bibcode=2020Mate...13.5776J }}</ref><ref>{{Cite web |title=Metals Program Overview |url=https://arpa-e.energy.gov/sites/default/files/documents/files/METALS_ProgramSummary.pdf |access-date=June 4, 2024 |website=arpa-e.energy.gov}}</ref> These materials are ideal for situations where high strength-to-weight ratio is more important than material cost, such as in aerospace and some automotive applications.<ref>{{Cite book |last1=Gialanella |first1=Stefano |url=http://link.springer.com/10.1007/978-3-030-24440-8 |title=Aerospace Alloys |last2=Malandruccolo |first2=Alessio |date=2020 |publisher=Springer International Publishing |isbn=978-3-030-24439-2 |series=Topics in Mining, Metallurgy and Materials Engineering |location=Cham |language=en |doi=10.1007/978-3-030-24440-8}}</ref>

Alloys specially designed for highly demanding applications, such as [[jet engine]]s, may contain more than ten elements.