Alloys

An alloy, generally speaking, is a combination of two or more elemental metals (or metals combined with non-metals) that retain the characteristics of a metal, such as electrical conductivity, malleability and ductility, luster, and so on. Below is a sample of some alloys — some well-known, some not so well known but important. Granted, a number of these materials are not within the reach of the average person, but it’s interesting to see the exotic materials that make up some of our everyday objects.

  • Aluminum – aluminum alloys are very important where strong, lightweight and corrosion-resistant metals are important, such as in the aerospace industry.
  • Brass – copper/zinc.
  • Bronze – primarily copper and often tin, with a variety of other metals and non-metals. Bronze is the first known alloy to be manufactured, with the earliest artifacts dating to the 5th millenium BC.
  • Copper – copper’s single most important use is in electrical wiring, as it is highly conductive and ductile. It is often alloyed with other metals to improve its hardness, or the other metal’s ductility.
  • Gallium – gallium alloys are used in thermometers as a non-toxic alternative to mercury.
  • Gold – gold is well known for being chemically inert, and for being the most malleable metal. Gold is everywhere in ornamentation, but it is rare to see pure gold anywhere. It is usually alloyed with other metals to improve hardness, and (in jewelry) to produce colored gold, such as white (gold and palladium or nickel), rose (gold/copper), green (gold/silver), blue (gold/iron), and purple (gold/aluminum).
  • Iridium – iridium is an extremely rare element most often used as an alloy with precious metals to produce fine bearings and standard weights and measures.
  • Pewter – pewter is mostly tin, with a small amount of antimony (formerly lead, which has been replaced due to its toxicity), and sometimes copper, bismuth, or silver. For centuries (as far back as the Bronze Age), pewter was important in the manufacture of tableware, but in modern times is largely used for decorative items.
  • Rhodium – the rarest and most valuable of the precious metal, rhodium is chemically inert. It is often used in alloys with platinum and palladium to manufacture plating that is corrosion-resistant at high temperatures (such as in the catalytic converters of car exhaust systems.)
  • Steel – iron/carbon, and, for example: chromium (particularly for stainless steels), cobalt, lithium, manganese, molybdenum, neodymium (to make powerful permanent magnets), nickel, niobium, platinum, silicon, tellurium, tungsten, witherite, and zinc. Arguably the single most important alloy in the history of humankind, there are dozens of different types of steel, with a tremendous variety of properties and uses, from massive girders to delicate surgical instruments, its utility in the modern world is hard to overestimate.
  • Silver – Elemental silver has the unique distinction of having the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Its best known alloy is sterling silver, in which copper is added to improve hardness, and other metals are added to reduce tarnishing.
Gallium liquid at skin temperature.
Like mercury, gallium has a very low melting point, which is why it is used as a non-toxic alternative in thermometers.
Catalytic converter
The catalytic converter of a car exhaust system: home to rhodium, the world’s rarest precious metal.
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