Aluminium bronze
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2008-04-10T05:51:38Z
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[[Image:AlubronzeCuAl20v500.png|thumb|Aluminium bronze with 20% Aluminium, V=50:1]]
'''Aluminium bronze''' is a type of [[bronze]] in which [[aluminium]] is the main [[alloy]]ing [[metal]] added to [[copper]]. A variety of aluminium bronzes of differing compositions have found industrial use, with most ranging from 5% to 11% aluminium by weight, the remaining mass being copper; other alloying agents such as [[iron]], [[nickel]], [[manganese]], and [[silicon]] are also sometimes added to aluminium bronzes.
==Compositions==
Following is a list of common standard aluminium bronze [[wrought alloy]] compositions, by [[ISO 428]] designations (proportional composition by weight; copper is the remainder by weight and is not listed):
{| class="wikitable"
|-
|Alloy
|[[Aluminium]]
|[[Iron]]
|[[Nickel]]
|[[Manganese]]
|[[Zinc]]
|[[Arsenic]]
|-
|'''CuAl<sub>5</sub>'''
|4.0% - 6.5%
|0.5% max
|0.8% max
|0.5% max
|0.5% max
|0.4% max
|-
|'''CuAl<sub>8</sub>'''
|7.0% - 9.0%
|0.5% max
|0.8% max
|0.5% max
|0.5% max
|
|-
|'''CuAl<sub>8</sub>Fe<sub>3</sub>'''
|6.5% - 8.5%
|1.5% - 3.5%
|1.0% max
|0.8% max
|0.5% max
|
|-
|'''CuAl<sub>9</sub>Mn<sub>2</sub>'''
|8.0% - 10.0%
|1.5% max
|0.8% max
|1.5% - 3.0%
|0.5% max
|
|-
|'''CuAl<sub>10</sub>Fe<sub>3</sub>'''
|8.5% - 11.0%
|2.0% - 4.0%
|1.0% max
|2.0% max
|0.5% max
|
|-
|'''CuAl<sub>10</sub>Fe<sub>5</sub>Ni<sub>15</sub>'''
|8.5% - 11.5%
|2.0% - 6.0%
|4.0% - 6.0%
|2.0% max
|0.5% max
|
|}
==Material properties==
Aluminium bronzes are most valued for their higher strength and [[corrosion]] resistance as compared to other bronze alloys. These alloys are [[tarnish]]-resistant and show low rates of corrosion in [[Earth's atmosphere|atmospheric]] conditions, low [[oxidation]] rates at high temperatures, and low reactivity with [[sulfur|sulfurous]] compounds and other [[exhaust gas|exhaust]] products of [[combustion]]. They are also resistant to corrosion in [[sea water]]. Aluminium bronzes' resistance to corrosion rests in the aluminium component of the alloys, which reacts with atmospheric [[oxygen]] to form a thin, [[tough]] surface layer of [[alumina]] (aluminium oxide) which acts as a barrier to corrosion of the copper-rich alloy.
Another notable property of aluminium bronzes are their [[biostatic]] effects. The copper component of the alloy prevents colonization by marine organisms including [[algae]], [[lichen]]s, [[barnacle]]s, and [[mussel]]s, and therefore can be preferable to [[stainless steel]] or other non-cupric alloys in applications where such colonization would be unwanted.
Aluminium bronzes tend to have a golden color.
==Applications==
Aluminium bronzes are most commonly used in applications where their resistance to corrosion makes them preferable to other engineering materials. These applications include [[bearing brush]]es and [[landing gear]] components on [[aircraft]], [[engine]] components (especially for sea-going ships), underwater fastenings in [[naval architecture]], and ship [[propeller]]s. The attractive gold-toned coloration of aluminium bronzes has also led to their use in [[jewelry]].
Aluminium bronzes are in the highest demand from the following industries and areas:
*General [[sea water]]-related service
*[[Water supply]]
*[[Oil]] and [[petrochemical]] industries eg tools for use in non-[[sparking]] environments
*Specialized anti-corrosive applications
*Certain [[structural retrofit]] building applications
Aluminium bronze can be [[welding|welded]] using the [[metal inert gas welding|MIG]] welding technique with an aluminium bronze core and pure [[argon]] gas.
Alloys similar to Aluminium bronze are used in making coins, for example the $1 and $2 [[coins of the Australian dollar|Australian coins]] produced by the [[Royal Australian Mint]] and the [[Nordic gold]] used for some [[Euro coins]].
==References==
*Copper Development Association. [http://www.cda.org.uk/megab2/corr_rs/pub80/default.htm "Publication Number 80: Aluminium Bronze Alloys Corrosion Resistance Guide"]. Retrieved [[July 18]] [[2005]].
*Copper Development Association. [http://www.cda.org.uk/megab2/corr_rs/pub80/default.htm "Publication Number 82: Aluminium Bronze Alloys Technical Data"]. Retrieved [[July 18]] [[2005]].
[[Category:Copper alloys]]
[[Category:Bronze]]
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