ABSTRACT
There are many useful metals that do not contain iron as their primary element, which can be used for structural as well as nonstructural purposes. These nonferrous metals are used in many everyday applications, such as beverage cans, compact disks (which have an aluminum layer), copper nickel coins, and jewelry made of gold, platinum, and silver. The corrosion behavior of copper limits its practical alloying level in gold, requiring the gold always be greater than 14 karat (i.e., the copper content must be less than 31.2%) because if it is less, the Cu content tends to dominate, resulting in a green oxide finish.
