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Aluminum Alloys
Article © MAIL User: Thadius

All About Aluminum


Useless Scientific Information


Atomic Number: 13
Atomic Radius: 143.1 pm

Atomic Symbol: Al
Melting Point: 660.32 C
Atomic Weight: 26.98154
Boiling Point: 2519 C
Electron Configuration: [ne]3s3p
Oxidation States: 3

History of Aluminum


Aluminum was first used by the ancient Greeks and Romans for use in dying and as an astringent. In 1827, Wohler successfully isolated the metal and discovered that it was an element. It was then named by Davy. Since its discovery, some other countries (outside of the US, that is) have used the name aluminium in place of aluminum. Funky, eh?

Where Do We Get It?


Perform electrolysis on some cryolite ore, which you can find in Greenland, and you get aluminum. In fact, aluminum is the most abundant metal in the earth's crust (not the center -- that's nearly all molten nickel), with over 8% of the crust composed of Aluminum. However, as abundant as aluninum is in nature, it's never found alone.

On to the Properties!


Pure aluminum is a silvery-white color. It's the second most malleable metal, sixth most ductile, is light, non-magnetic, and non-sparkling. I for one love the sparkling effect of certain metals, but that's just me.

Uses of Aluminum


Any application where a light-weight metal is needed and titanium is not feasible, you will find aluminum. Its most important use is, of course, maille bikinis. There's nothing better!

Non-Heat-Treatable Alloys


These alloys can be work hardened. They are not heat-treatable because these alloys contain manganese, iron, silicon, magnesium, or a combination of the above. Most of these alloys must be heat-stabilized before they are ready for industrial use. They typically are the 1000, 3000, 4000, or 5000 series alloys.

Heat-Treatable Alloys


These alloys cannot be work hardened. They usually contain copper, magnesium, zinc, or silicon. In addition, they can be heat-treated to substantially increase their strength.

Effects of Alloying Elements


(Note: This part is copy-pasted, from http://www.key-to-metals.com/Article2.htm)

1xxx series - Aluminum of 99 percent or higher purity has many applications, especially in the electrical and chemical fields. Excellent corrosion resistance, high thermal and electrical conductivity, low mechanical properties and excellent workability characterize these compositions. Moderate increases in strength may be obtained by strain-hardening. Iron and silicon are the major impurities.

2xxx series - Copper is the principal alloying element in this group often with magnesium as secondary addition. These alloys require solution heat-treatment to obtain optimum properties. In some instances artificial aging is employed to further increase the mechanical properties. This treatment materially increases yield strength, with attendant loss in elongation. Its effect on tensile strength is not so significant. The alloys in this series do not have as good corrosion resistance as most other aluminum alloys, and under certain conditions they may be subject to intergranular corrosion.

3xxx series - Manganese is the major alloying element of alloys in this group, which are generally non-heat-treatable. Because only a limited percentage of manganese, up to about 1.5 percent, can be effectively added to aluminum, it is used as a major element in only a few instances.

4xxx series - The major alloying element of this group is silicon, which can be added in sufficient quantities (up to 12%) to cause substantial lowering of the melting point without producing brittleness in the resulting alloys. For these reasons aluminum-silicon alloys are used in welding wire and as brazing alloys where a lower melting point than that of the parent metal is required.

5xxx series - Magnesium is one of the most effective and widely used alloying elements for aluminum. When it is used as the major alloying element or with manganese, the result is a moderate to high strength non-heat-treatable alloy. Alloys in this series possess good welding characteristics and good resistance to corrosion in marine atmosphere.

6xxx series - Alloys in this group contain silicon and magnesium in approximate proportions to form magnesium silicone, thus making them heat-treatable. Though less strong than most of the 2xxx or 7xxx alloys, the magnesium-silicon alloys possess good formability and corrosion resistance, with medium strength.

7xxx series Zinc in amounts of 1 to 8% is the major alloying element in this group, and when coupled with magnesium and copper (or without copper) results in heat-treatable alloys of very high strength. Usually other elements such as manganese and chromium are also added in small quantities. The out-standing member of this group is 7075, 7050 and 7049, which is among the highest strength alloys available and is used in air-frame structures and for highly stressed parts.


Hope you enjoyed the read!
Original URL: http://www.mailleartisans.org/articles/articledisplay.php?key=255