Alloy

---

---

Photo by: marilyn barbone

An alloy is a mixture of two or more metals. Some familiar examples of alloys include brass, bronze, pewter, cast and wrought iron, steel, coin metals, and solder (pronounced SOD-der; a substance used to join other metallic surfaces together). Alloys are usually synthetic materials, developed by scientists for special purposes. They generally have specially desirable properties quite different from the metals from which they are made. As an example, Wood's metal is a mixture of about 50 percent bismuth, 10 percent cadmium, 13 percent tin, and 27 percent lead that melts at 70°C (160°F). This low melting point makes Wood's metal useful as a plug in automatic sprinkler systems. Soon after a fire breaks out, the heat from the flames melts the Wood's metal plug, releasing water from the sprinkler system.

Important Alloys, Their Composition, and Typical Uses

Alloy	Composition	Uses
Babbitt metal	tin: 90%	used in bearings because of its low measure of fricti with steel
	antimony: 7%
	copper: 3%
bell metal	copp 77%	casting of bells
	tin : 23%
brass	copper with up to 50% zinc	inexpensive jewelry; hose nozzles and couplings; piping; stamping dies
bronze	copper with up 12% tin	coins and medals; heavy gears; tools; electrical hardware
coin metal	copper: 75%	U.S. coins
	nickel
duralumin	aluminum: 95%	aircraft, boats, railroad cars, and machinery because of its high strength and resistance to corrosion
	copper: 4%
	manganese: <1%
	magnesium: 0.5%
monel	nickel 60%	corrosion-resistant containers
	copper: 33%
	iron: 7%
Nichrome®	nickel: 80-85%	heating elements in toasters, electric heaters, etc.
	chromium: 15-20%
phosphor bronze	bronze with a small amount of phosphorus	springs electrical springs, boat proellers
solder	lead: 50%	joining two metals to each other
	tin: 50%
sterling silver	silver: 92.5%	jewelry, art objects
	copper: 7.5%
type metal	lead: 75-95%	used to make type for printing because it expands as it cools
	antimony: 2-18%
	tin: trace