Scientists Say: Alloy

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Alloy (noun, “AL-oy”)

An alloy is a metal-based mixture. Familiar examples of alloys include steel, bronze and brass. Some alloys are metal-metal mixtures. Others mix metals with nonmetals.

Alloys offer strong, flexible support for skyscrapers, jewelry and more. By adjusting the recipe of an alloy, metalworkers can fine-tune its properties. That way, they create the perfect material for the job.

Take steel. This alloy contains the elements iron and carbon. Iron is metallic element. Adding carbon to it strengthens the metal. The result is a versatile metal alloy that is strong, flexible and resilient. That makes it perfect for making everything from a thin knife blade to scaffolding for our tallest buildings.

An alloy made only of carbon and iron is called carbon-steel. But often, chemists add other elements to fine-tune the properties. For instance, a little bit of chromium added to the mix creates stainless steel. This upgraded version greatly increases steel’s resistance to rust. It works because the chromium combines with oxygen in the air. Technically, this is how rust forms. But in the case of stainless steel, the chromium “rust” forms a barrier that does not flake away like iron rust. This barrier protects the iron — which, on its own, is a very rust-prone metal.

Pure silver is a metal element. But sterling silver is an alloy. For millennia, silver’s beautiful, rust-resistant gleam has inspired craftsmen to create jewelry. In the modern age, silver’s high electrical conductivity makes it an important metal for electronics. However, silver is rarely used on its own. Like gold, silver is a “soft” metal. Jewelry made from pure silver would warp out of shape. So, metalworkers blend in a bit of copper or some other metal for added strength. Almost all silver jewelry is made from alloys. To be considered “sterling” silver, the alloy must contain 92.5 percent silver.