Is the aluminum used in planes, cans, and foil all molecularly the same?
Is thickness the only difference in each?
Is it pure aluminum in each application, or an alloy?
Aluminum has limited structural uses when pure. In aircraft, it is almost 100% of the time a decently strong alloy.
A thread about aluminum collected from scrap drives during WW2 (and its uses) can be found here: http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=118386. There’s also a link to Cecil’s column on these scrap drives about a third of the way down.
Pure aluminum is too soft to be useable for anything but decoretive purposes. All structural and aircraft aluminum, and even that used for aluminum cans, is an alloy.
There are a lot of different aluminum alloys, with varying strength, ductility, corrosion resistance, weldability, etc.
For information on any particular aluminum alloy (or any of thousands of other types of materials), check out www.matweb.com
[nitpick] Actually pure aluminum has a very important role in our local float plane airline industry on the west coast of British Columbia. A local airline that I have worked for purchases aluminum sheet metal called Alclad (not the lacquer) to complete skin restorations on aircraft subject to a heavily corrosive environment.
Alclad sheet metal is surfaced for several mls with pure aluminum to resist corrosion penetration to the alloy underneath.
I found this on the net… http://naca.larc.nasa.gov/reports/1927/naca-tn-259/ going back to 1927 or this , a more modern reference … http://www.inovati.com/pages/products/coatingservices/arc.html
[/nitpick]
In almost all cases, the aluminum that you’ll come in contact with is an alloy. Aluminum alloys are usually given 4 number classifications, YXXX, where the Y designates the alloying element. In general Aluminum is a light and ductile material. For some applications, such as aircraft structural members, an alloying element like Cu is used. This type of alloy is what is known as age-hardenable. Normally, the Cu atoms are dispersed uniformly throughout the matrix. However, when the material is heated the Cu forms precipitates (Guinier-Preston zones at the begining). These Cu precipitates cause a strain field within the matrix that pin dislocations (dislocation motion is a mechanism of plastic deformation, inhibition of plastic deformation increases the strength of the material).
Basic metallurgy stuff.
2024 is the most common alloy used for aircraft structual components (it is subject to corrosion, so is generally ‘alclad’ (thin coating of pure Al for corrosion resistance).
6061 is the stuff the hardware store sells
6063 is what your windows are made of.
Your Coke can is either 1100 or 3003.
alloys:
1xxx - at least 99% aluminum
2xxx - Copper
3xxx - Manganese
4xxx - Silicon
5xxx - Magnesium and Silicon
7xxx - Zinc
8xxx - Other
High purity aluminum (for brits aluminium) is used in cryogenic storage tanks. Its cheaper than nickel steel and a lot lighter, (and it can withstand low temperatures without getting brittle) so it is used for floating heads of cryogenic storage tanks.
Ok, so pure aluminum is pretty soft, so any anything structural is going to be an alloy – even down to a soda can. Is that right?
What about foil? Also an alloy, or is its necessary properties (thin, extremely maleable) well suited for pure aluminum?
both 1100 and 3003 are, essentially, pure Al.
Don’t know about foil - it probably is 1100 (pure).
and, correction:
5xxx - Magnesium
6xxx - Magnesium and Silicon
Answer (from the Reynolds Wrap site):
Which is relatively pure; 1100 (“pure”) may contain up to 1% other elements. Other alloys contain a substantial amount of other elements. 7075, for instance (a high-strength alloy) contains ~10% copper, magnesium, zinc, and chromium. The common 2024 contains ~6.5% copper, manganese, and magnesium.