IV.

Uses

A given volume of aluminum weighs less than one-third as much as the same volume of steel. The only lighter metals are lithium, beryllium, and magnesium. Its high strength-to-weight ratio makes aluminum useful in the construction of aircraft, railroad cars, and automobiles, and for other applications in which mobility and energy conservation are important. Because of its high heat conductivity, aluminum is used in cooking utensils and the pistons of internal-combustion engines. Aluminum has only 63 percent of the electrical conductance of copper for wire of a given size, but it weighs less than half as much. An aluminum wire of comparable conductance to a copper wire is thicker but still lighter than the copper. Weight is particularly important in long-distance, high-voltage power transmission, and aluminum conductors are now used to transmit electricity at 700,000 V or more.

The metal is becoming increasingly important architecturally, for both structural and ornamental purposes. Aluminum siding, storm windows, and foil make excellent insulators. The metal is also used as a material in low-temperature nuclear reactors because it absorbs relatively few neutrons. Aluminum becomes stronger and retains its toughness as it gets colder and is therefore used at cryogenic temperatures. Aluminum foil 0.018 cm (0.007 in) thick, now a common household convenience, protects food and other perishable items from spoilage. Because of its light weight, ease of forming, and compatibility with foods and beverages, aluminum is widely used for containers, flexible packages, and easy-to-open bottles and cans. The recycling of such containers is an increasingly important energy-conservation measure. Aluminum's resistance to corrosion in salt water also makes it useful in boat hulls and various aquatic devices.

A wide variety of coating alloys and wrought alloys can be prepared that give the metal greater strength, castability, or resistance to corrosion or high temperatures. Some new alloys can be used as armor plate for tanks, personnel carriers, and other military vehicles.