Alloys are mixtures of different metals. In most cases, the different metals are mixed in ratios that don’t occur in nature. The result is a material with properties that are different from those of its individual components. The most common alloys are those that contain a metal such as steel or bronze that is combined with another metal such as copper, zinc, nickel, or tin. Since most alloys have useful properties, it is important for engineers and designers to understand their properties.
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Why make metal alloys?
Alloys are made to create useful new materials with specific properties that cannot be achieved with the ingredients alone. The most common applications for alloys are in construction, transportation, and energy. Alloys can be either ferrous or non-ferrous. Ferrous alloys have iron as the main ingredient. Examples of ferrous alloys include cast iron and steel. Ferrous alloys can be made from various raw materials such as pig iron, iron ore, or scrap. Non-ferrous alloys do not contain iron. Examples of non-ferrous alloys include brass, bronze, and plastics.
How are alloys made?
It all starts with mining the elements that are needed in the alloys. This can require big mines that dig deep into the earth to gather the resources. More recently companies are also trying to recycle more and more to gather these resources from old devices.
To create an alloy, metallurgists blend different mixtures of metals. The most common alloying elements are air, silicon, and oxygen. Other elements, such as carbon, hydrogen, nitrogen, and sulphur, may also be present in some alloys. The proportions of the ingredients in the alloy can vary. For example, an alloy can contain as much as 40% carbon. The blending of different alloys to create new materials with specific properties is an ancient process.
It is essential that the right mix is created. Therefore it is made in big factories that have advanced sensors. The process can be compared to cooking as you mix different elements at a specific temperature and let them cool down in a specific way.
This whole process is automated and big machines produce alloys 24/7. These machines have to withstand a lot of heat and have to be maintained from time to time to check if nothing has broken. This requires a lot of resources to get started and this is why alloys are mainly made in big factories.
What are the properties of an alloy?
The properties of an alloy vary depending on the ingredients of the alloy. For example, an alloy that contains mostly iron will have a higher metal density than one that contains mostly copper. Metal densities, metal alloys with different metal contents, and melting points are a few of the properties of alloys. Metal alloys can have a wide range of densities, from very heavy alloys with densities over 9 grams per cubic centimeter (g/cm3) down to light alloys with densities under 7 g/cm3. The density of an alloy affects its strength, which can vary from very low (brass and bronze) to very high (stainless steel, titanium) depending on the alloy and application.
Researchers are developing new alloys to meet the demands of consumers and businesses. There are always ways to improve the alloys so that they can be used in more applications.
Alloys in everyday life
Alloys are used in a variety of everyday products. Many cars, for example, are made with steel. Other common alloys include aluminum, magnesium, and zinc. In addition to their uses in construction and transportation, alloys are found in the kitchen. Some of these alloys include cast iron, aluminum, and zinc. Cast iron is often used in pots and pans because it can withstand high temperatures without warping or wearing out. Aluminum and zinc are used in food cans and foil because they are lightweight and easily recycled.
Stainless steel is another example of an alloy. This makes steel less prone to rusting and this allows us to use it in a lot of applications such as dishwashers and washing machines. Adding these alloys increases the price though so there are disadvantages to it as well.
Other properties of alloys
Alloys have other useful properties. For example, some alloys are magnetic. When a piece of iron is mixed with nickel, a significant proportion of the iron becomes magnetized. As a result, alloys with a high percentage of nickel become strong magnets. Practical applications for magnets in everyday life include keeping important documents and pictures close at hand and avoiding losing small, valuable items. Alloys with a low percentage of nickel, such as bronze, are generally non-magnetic.
How to identify an alloy?
In order to identify an alloy, metallurgists examine its chemical composition. The composition of an alloy can be determined by using a Scanning Electron Microscope (SEM). The instrument is used to examine the grain size, shape, and structure of an alloy. Other methods used to identify alloys include atom probe analysis, Raman spectroscopy, and X-ray diffraction.
Companies do quality checks once the alloys have been made to make sure that nothing went wrong. If there was for example too much oxygen during the production process, the metal can be more fragile. In some applications, such as skyscrapers, it is essential that the material has the desired strength. A lot of tests can be performed to make sure that the materials have the desired qualities. This can be essential to ensure the strength and durability of the material.
A lot of factories receive big spools of metal that they use in their production processes. For them, it is essential that the metal is consistent and the quality is up to their specifications and requirements. If there is an issue, they can contact the supplier of the alloys to see what is going on and examine it further.
Conclusion
Alloys are made by combining different metals to create new materials with specific properties. Because most alloys have useful properties, it is important for engineers and designers to understand how they are made and what their properties are.
