Editing Aluminium (section)

=== Bulk ===
[[File:Lingot aluminium.jpg|thumb|left|Aluminium ingot from furnace]]

Aluminium metal has an appearance ranging from silvery white to dull gray depending on its [[surface roughness]].{{efn|The two sides of aluminium foil differ in their luster: one is shiny and the other is dull. The difference is due to the small mechanical damage on the surface of dull side arising from the technological process of aluminium foil manufacturing.<ref name="ReynoldsKitchens">{{Cite web
|title=Heavy Duty Foil
|url=https://www.reynoldskitchens.com/products/aluminum-foil/heavy-duty-foil/|website=Reynolds Kitchens|language=en|access-date=20 September 2020
|archive-date=23 September 2020|archive-url=https://web.archive.org/web/20200923185810/https://www.reynoldskitchens.com/products/aluminum-foil/heavy-duty-foil/ |url-status=live}}</ref> Both sides reflect similar amounts of visible light, but the shiny side reflects a far greater share of visible light [[specular reflection|specularly]] whereas the dull side almost exclusively [[Diffuse reflection|diffuses]] light. Both sides of aluminium foil serve as good [[Reflectance|reflectors]] (approximately 86%) of [[visible light]] and an excellent reflector (as much as 97%) of medium and far [[infrared]] radiation.<ref name="Pozzobon">{{Cite journal
|last1=Pozzobon|first1=V.|last2=Levasseur|first2=W.|last3=Do|first3=Kh.-V.|display-authors=3|last4=Palpant|first4=Bruno|last5=Perré|first5=Patrick|date=2020
|title=Household aluminum foil matte and bright side reflectivity measurements: Application to a photobioreactor light concentrator design
|journal=Biotechnology Reports|language=en|volume=25|pages=e00399|doi=10.1016/j.btre.2019.e00399|pmc=6906702|pmid=31867227 | issn=2215-017X }}</ref>}} Aluminium mirrors provides high reflectivity for light in the [[ultraviolet]], visible (on par with silver),<ref>{{Cite journal |last=Hummel |first=R.E. |date=1981 |title=Reflectivity of silver- and aluminium-based alloys for solar reflectors |url=https://linkinghub.elsevier.com/retrieve/pii/0038092X81900402 |journal=Solar Energy |volume=27 |issue=6 |pages=453 |doi=10.1016/0038-092x(81)90040-2 |bibcode=1981SoEn...27..449H |issn=0038-092X}}</ref> and the far [[infrared]] region.<ref>{{Cite book |last1=Hass |first1=G. |last2=Heaney |first2=J. B. |last3=Hunter |first3=W. R. |title=Physics of Thin Films - Advances in Research and Development |date=1982 |editor-last=Hass |editor-first=Georg |editor2-last=Francombe |editor2-first=Maurice H. |editor3-last=Vossen |editor3-first=John L. |chapter=Reflectance and Preparation of Front Surface Mirrors for Use at Various Angles of Incidence from the Ultraviolet to the Far Infrared |chapter-url=https://linkinghub.elsevier.com/retrieve/pii/S0079197013700082 |publisher=Elsevier |volume=12 |pages=8 |doi=10.1016/s0079-1970(13)70008-2|isbn=978-0-12-533012-1 }}</ref> Aluminium is also good at reflecting [[solar radiation]], although prolonged exposure to sunlight in air can deteriorate the reflectivity of the metal;<ref>{{Cite journal |last=Hummel |first=R. E. |date=1981-01-01 |title=Reflectivity of silver- and aluminium-based alloys for solar reflectors |url=https://linkinghub.elsevier.com/retrieve/pii/0038092X81900402 |journal=Solar Energy |volume=27 |issue=6 |pages=449–455 |doi=10.1016/0038-092X(81)90040-2 |bibcode=1981SoEn...27..449H |issn=0038-092X}}</ref> this may be prevented if aluminium is [[anodization|anodized]], which adds a protective layer of oxide on the surface.{{citation needed|date= March 2025|reason =While may be intuitive, this should have a source supporting this claim}}

The density of aluminium is 2.70&nbsp;g/cm<sup>3</sup>, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness.{{sfn|Lide|2004|p=4-3}} Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. The only lighter metals are the metals of [[alkali metal|groups 1]] and [[alkaline earth metal|2]], which apart from [[beryllium]] and [[magnesium]] are too reactive for structural use (and beryllium is very toxic).<ref>{{cite journal
|title=A brighter beryllium|date=2011|last1=Puchta|first1=Ralph
|journal=Nature Chemistry|volume=3|issue=5|pages=416|pmid=21505503|bibcode=2011NatCh...3..416P|doi=10.1038/nchem.1033|doi-access=free}}
</ref> Aluminium is not as strong or stiff as steel, but the low density makes up for this in the [[aerospace]] industry and for many other applications where light weight and relatively high strength are crucial.{{sfn|Davis|1999|pp=1–3}}

Pure aluminium is quite soft and lacking in strength. In most applications various [[aluminium alloys]] are used instead because of their higher strength and hardness.{{sfn|Davis|1999|p=2}} The [[yield (engineering)|yield strength]] of pure aluminium is 7–11 [[Pascal (unit)|MPa]], while [[aluminium alloy]]s have yield strengths ranging from 200 MPa to 600 MPa.<ref name="Polmear1995">{{cite book
|last1=Polmear|first1=I.J.|date=1995
|title=Light Alloys: Metallurgy of the Light Metals
|edition=3|publisher=[[Butterworth-Heinemann]]|isbn=978-0-340-63207-9}}
</ref> Aluminium is [[ductility|ductile]], with a percent elongation of 50–70%,<ref name="Cardarelli 2008 p158-163">{{Cite book
|last=Cardarelli|first=François|title=Materials handbook : a concise desktop reference|date=2008
|publisher=Springer|isbn=978-1-84628-669-8|edition=2nd|location=London|pages=158–163|oclc=261324602}}
</ref> and [[malleable]] allowing it to be easily [[drawing (metalworking)|drawn]] and [[extrusion|extruded]].{{sfn|Davis|1999|p=4}} It is also easily [[machining|machined]] and [[casting (metalworking)|cast]].{{sfn|Davis|1999|p=4}}

Aluminium is an excellent [[Heat conduction|thermal]] and [[electrical conductor]], having around 60% the conductivity of [[copper]], both thermal and electrical, while having only 30% of copper's density.{{sfn|Davis|1999|pp=2–3}} Aluminium is capable of [[superconductor|superconductivity]], with a superconducting critical temperature of 1.2 [[kelvin]] and a critical magnetic field of about 100 [[gauss (unit)|gauss]] (10 [[millitesla]]s).<ref>
{{cite journal
 |last1=Cochran |first1=J.F.
 |last2=Mapother |first2=D.E.
 |date=1958
 |title=Superconducting Transition in Aluminum
 |journal=[[Physical Review]]
 |volume=111 |issue=1 |pages=132–142
 |bibcode=1958PhRv..111..132C
 |doi=10.1103/PhysRev.111.132
}}</ref> It is [[paramagnetic]] and thus essentially unaffected by static magnetic fields.{{sfn|Schmitz|2006|p=6}} The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of [[eddy currents]].{{sfn|Schmitz|2006|p=161}}