ALUMINUM OCCUPIES 17% THE WEIGHT OF THE EARTH'S CRUST, AND HAS SILVER APPEARANCE. IN 1880S, ALUMINUM WAS CONSIDERED AS A PRECIOUS METAL, MORE VALUABLE THAN GOLD AND SILVER. WITH SUPERIOR ADVATAGES OF DURABILITY, STAINLESS ABILITY AND EASE OF PROCESSING, ALUMINUM ALLOY IS GRADUALLY BECOMING AN IMPORTANT MATERIAL, CONTRIBUTING TO VARIOUS INDUSTRIES SUCH AS AEROSPACE, MILITARY, TELECOMMUNICATION, CONSTRUCTION AND OTHERS.