ABSTRACT
The use of aluminium in construction is second only to that of steel. The liquid aluminium sinks to the bottom of the bath, where it is periodically collected and cast either into its final form after adding any required alloying materials or into ingots for subsequent remelting. In the classification scheme adopted by many countries and described in BS EN 573, these are divided into eight series depending on the principal alloying element: Within each series designation, the second, third and fourth digits are used to indicate the proportions of all the alloying elements. Casting alloys are generally based on a eutectic alloy system, with aluminium combined with up to 13" silicon being widely used. The alloys that are suitable for heat treatment are also known as age-hardenable alloys. Aluminium can in principle be recycled indefinitely, as remelting and refining results in no loss of properties.
