The stainless steel forks in your kitchen drawer and the rose gold bracelet on your wrist are a few everyday things made of metal alloys—combinations of different metals in varying proportions. Humans began making metal tools out of bronze, a combination of copper and tin, around 3300 BC and have been refining different combinations of metals and elements ever since. These metal mixtures are called alloys, and they’re part of everyday life.
Steel is probably the most common metal alloy in use today. Made from iron and carbon, steel is stronger and lighter than iron. There are different types of steel:
Stainless steel: steel blended with chromium. It’s “stainless” because it resists corrosion. The chromium in stainless steel oxidizes and forms a protective outer layer for the iron in the steel, unless it’s exposed to really corrosive conditions, like salt water. You probably have some stainless steel utensils in your kitchen drawer.
Carbon steel: has a higher level of carbon and melts at lower temperatures. It is stronger and harder than stainless steel but subject to corrosion. Used for kitchen knives.
Other steel alloys: steel combined with other metals like nickel, copper, chromium, magnesium, or aluminum. Your car’s wheels may be made of a steel and aluminum alloy; if they’re made with magnesium, then you’ve got “mag” wheels. Racing car manufacturers used “mag” wheels because they were lighter and dissipated heat better than steel alone.
You see it in doorknobs, bathroom fixtures, and door knockers. Orchestras have brass sections made up of trumpets, trombones, French horns, and tubas. Brass combines copper and zinc.
Those greenish sculptures in the park are likely made of bronze, a combination of copper and tin. First used in the Middle East thousands of years ago, bronze is great for molded statues because it expands a little when it cools off, filling all the nooks and crannies of the mold.
Often used in jewelry, sterling silver is usually a combination of silver and copper. The copper reduces silver’s tendency to tarnish.
White and Rose Gold
White gold is a combination of gold and silver, nickel, or palladium. Combined with nickel, white gold is stronger, and with palladium, it is softer and used to form the settings of gems in rings and other jewelry. Rose gold is copper with gold, sometimes along with silver.
Your favorite heavy black frying pan is probably made of cast iron, a mix of iron, carbon, and perhaps silicon. Cast iron is different than wrought iron, used for decorative fences. Cast iron is molded, and wrought iron is pounded into shape, reheated, and pounded again. Wrought iron may go through several rounds of shaping and reheating, whereas cast iron cools in a mold to form its final shape.
The next time you notice everyday items made of metal, you may be looking at things made of metal alloys that took years, and lots of trial and error, for humans to perfect but now are used regularly in jewelry, cutlery, construction, or musical instruments.