Aluminum is now the second most widely used metal in the world following iron. Aluminum is a silvery-white ductile metallic element. It is the most abundant metallic element in the earth's crust although it is not commonly found in concentrated form. The principal source of aluminum is the rock Bauxite. Aluminum has a number of physical and chemical properties which allow it to be used in a broad range of applications.
The physical properties of aluminum include its light weight and density one third that of steel. The low density does not affect its strength, and unlike most steel grades, aluminum does not become brittle at low temperatures, its strength actually increases. When combined with elements such as copper, silicon, or magnesium it forms alloys of great strength. The ductile nature of the metal means it has superior malleability which is essential in many manufacturing processes such as extrusion, and in rolling of strips and foils. It is also easily worked using many machining methods such as milling, drilling, and cutting.
Aluminum is also an excellent conductor of heat and electricity, where an aluminum conductor may weigh half the weight of a copper conductor with the same conductivity.
Aluminum has several unique chemical properties. Iron exposed to air oxidizes and forms rust, a chemical reaction which begins the decay of the iron. Aluminum also reacts with oxygen in the air, but in its case to form an extremely thin layer of oxide. This thin, dense layer provides excellent corrosion protection and is self-repairing if damaged. Anodizing increases the thickness of the oxide layer. In neutral and slightly acidic environments aluminum is extremely durable. In addition, aluminum has zero toxicity, aluminum compounds also occur naturally in our food.
Finally, aluminum is one of the most environmentally friendly metals in use today. Its easy recyclability is unlimited and uses only 5% of the original energy consumption when remelting products.