Alloy
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 |