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What are metal alloys?

What exactly are metal alloys and what do they do for cars?

Ashlea Parker
- Sydney, NSW, Australia
2003

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2003

Hello Ashlea!

Metal alloys are combinations of metals which give different structures, and hence different properties, to the metal. Common alloys include:

• steel, an alloy of iron and carbon, often with small amounts of nickel, chromium, or molybdenum
• stainless steel, which has at least 12% chromium (some folks say 10.5%), which makes it resistant to rusting
• brass, an alloy of copper and zinc, which is harder and stronger than the pure constituents
• solder, often tin and lead, composition varies to adjust the melting point

We could get a lot more wordy and technical, talking about how some mixtures of metals are NOT alloys- such as Albemet, a.k.a. the olde lockalloy, which is a mixture of beryllium and aluminum. Yet since they don't really mix (a la oil and water) you have islands of Be co-existing with Al, so the structure doesn't change and the properties are merely the mixture of the two metals. But I'm uncertain of the level of expertise you seek, or what you can readily digest.

Regarding cars, I can only think of a few uses for pure metals. There are chromium and cadmium plated items, and these 25 micron and 5 micron thick coatings are fairly pure. I can also believe that some magnetic circuit components may contain pure iron armatures or polepieces. The copper wiring is pretty pure, as are some of the platings in the electronics. Yet most structural parts, and the GREAT majority of the metal in the car, are alloyed.

Hope this helps!

Lee Gearhart
metallurgist - E. Aurora, New York