You’ve probably heard the word “alloy” come up in conversations about buildings or fighter jets, but did you know you encounter alloys almost every day? The average person doesn’t know what alloy is or how it is used, or else they assume it’s a type of metal only used in engineering. Learning the truth about alloys can help you understand the metals you come into contact with every day, as well as why the world relies on alloys.
In basic terms, an alloy is a metal created by melting and mixing two or more other metals together. Mixing a metal and another material, a nonmetal, together can also make alloy. The two substances are intimately united – fused together and dissolving into one another in molten form. Alloys are combined in a way that makes it impossible to separate the two by physical means.
The goal of creating alloys is to attain a metal with enhanced durability or another desired property such as magnetism, electricity, formability, or temperature resistance. Creating an alloy reduces a metal’s purity by mixing it with a less valuable metal. For example, the mixing of copper and zinc reduces both metals in purity when they are combined to create brass. Examples of common alloys include:
Steel: An alloy of iron, carbon, and other elements
Stainless steel: A combination of iron, chromium, and nickel
Pewter: A blend of tin, antimony, and copper
18-carat gold: 75% gold, 25% a combination of nickel, copper, and zinc
Beryllium-copper: A mix of beryllium and copper to form copper with high electrical conductivity
Nickel and cobalt: A superalloy used in aircraft engines
Aluminum, silicon, iron, copper, and magnesium: Aluminum alloys are specifically designed for beverage cans
Copper and zinc: Brass for fittings
Copper and tin: Bronze for plumbing fixtures
A superalloy is a high-performance alloy that has great mechanical strength, heat resistance, surface stability, and corrosion resistance. Engineers use superalloys as important strengthening mechanisms while building turbine engines and load-bearing structures. Superalloys are often mixtures of nickel, nickel-iron, or cobalt with another element.
How Do We Make Alloys?
Often, pure metals are not strong or durable enough to withstand the pressures of oxidation, heavy weight, or simple everyday wear-and-tear. Iron, for example, is brittle and rusts easily by itself. If you mix iron with carbon and silicon, however, you get cast iron – an alloy we depend on for metal structures such as bridges. Aluminum is soft and weak in its natural form, but mixing it with magnesium, manganese, and copper creates duralumin, an alloy powerful enough to build airplanes.
Creating alloys is a delicate process that can take three different forms. In the traditional process, we heat each component until it reaches its molten, or liquid, form. Then, we blend the two metals – or the metal and nonmetal – intrinsically together and allow them to cool. The finished product is called a solid solution. The second process is powder metallurgy. Each component is instead turned into a powder, mixed together, and fused using high temperatures and pressures.
The third way of creating alloys is the most complex, and it is how we create the semiconductors inside electronic circuits and computer chips. Scientists fire beams of ions into the surface layer of metal in a process called ion implantation. This is the most precise way of creating an alloy. Substitution alloys occur when the atoms of the smaller elements replace the atoms of the main metal. If the atoms slip in between the main metal’s atoms, it’s known as an interstitial alloy. Brass is a substitution alloy, while steel is an interstitial alloy.
Alloys All Around Us
Today we use alloys in hundreds of ways. Over 90% of metals used today are in the form of alloys. The uses of alloys are as innumerable as our own imagination and innovation. Common alloys we encounter every day include white gold, sterling silver, bronze, brass, and steel. Alloys make up many household products – soda cans, jewelry, cutlery, hardware, magnets, door locks, musical instruments, cookware, coins, and tools. Even dental fillings are alloys, made of mercury mixed with silver, tin, copper, and zinc.
Alloys are indispensable in today’s modern world. From the alloy bolts and nuts that hold skyscrapers together to the knives and forks in your kitchen, alloys surround us. It’s difficult to picture a world without them. Eliminating alloys means taking away airplanes, vehicle bridges, most automobiles, and electrical appliances. Now that you know what alloys are and what they do, you can have a better appreciation for these superb metal mixtures.
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