Aluminium

Aluminium is the silvery white member belongs to the boron group of chemical elements. The symbol of aluminium is Al and the atomic number is 13. Under normal substances it is not soluble in water. It is the third most abundant element next to oxygen and silicon. As a free metal it is too reactive chemically to occur in nature. Bauxite ore is the chief source of aluminium and is found combined over 270 different minerals.

Due to passivation, aluminium has the ability to resist corrosion and it is remarkable for the low density. Aluminium is more rapidly used in the field of aviation for construction of aircraft body, due to its less weight and high ability to resist corrosion, it is used over there. The advantage of Aluminium is less weight and more rigid. It is used in other areas like transportation and buildings.

In spite of its occurrence in the environment, Aluminium salts are not known to be used by any form of life. If soluble aluminium salts are delivered in quantity by injection to animals, it has some verified toxicity. Still there is controversy exists about aluminium, is that possible long term toxicity to humans from larger ingested amounts.

Characteristics of Aluminium

Aluminium is soft, durable, light weight, ductile, and malleable metal. It is non magnetic and non sparking. The pure aluminium has the yield strength of 7 -11 MPa, whilst the alluminium alloy have ranging from 200 MPa – 600 MPa. It has about 1/3 the density and stiffness of steel. It is easy to machined, cast, and extruded.

It is highly corrosion resistant due to the thin surface layer of aluminium oxide that forms when the metal is exposed to air, preventing from oxidation. Due to galvanic reactions, the strongest aluminium is less corrosion resistant with alloyed copper.

Aluminium mirror finish has the highest reflectance of any metal in the 200-400 nm and the 3000-10000 nm regions; in the 400-700nm visible range it is slightly outperformed by tin and silver. It is the good thermal and electrical conductor, and having 62% of copper conductivity.

Structural Applications

The strength and durability of aluminium allows widely varies, not only as a result of components of the particular alloy, but also as the result of heat treatments and manufacturing process. The fatigue strength is the important structural limitation of aluminium alloy. The fatigue failure will occur eventually because aluminium alloy have no well defined fatigue limit. Another important property of aluminium is their sensitivity towards heat.  Like all structural alloys, aluminium alloy also subject to the internal stress following heating operations such as welding and casting.

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