chemistry

Alloy: Examples, properties and Types

It is called alloy to the process by which combine two or more elements, usually metal, in a single unit that wins the properties of both . Alloys are mainly considered mixtures, since the atoms of the combined components do not produce, except in rare occasions, chemical reactions that interlock their atoms.Normally, the substances used in alloys are metallic: iron, aluminum, copper, lead, etc., but a metallic element can also be combined with a non-metallic one: carbon, sulfur, arsenic, phosphorous, etc.

However, the material resulting from the mixture always has metallic characteristics (it shines, conducts heat and electricity, has more or less hardness, more or less malleability, more or less ductility, etc.), modified or strengthened with the additional ones of the other substance.

Types of alloys

Alloys are usually distinguished based on the predominance of one element over the others (for example, copper alloys), but they are also classified according to the number of elements involved in the mixture , namely:

  • Binary . They consist of two elements (the base element and the aleante).
  • Ternary . They consist of three elements (the base element and two alloying elements).
  • Quaternary . They are made up of four elements (the base element and three aleantes).
  • Complex . They consist of five or more elements (the base element and four or more alloying elements).

Another possible classification distinguishes between heavy and light alloys, according to the properties of the base metal substance . Thus, aluminum alloys will be light, but iron alloys will be heavy.

Alloy properties

The specific properties of each alloy depend on the elements involved in the mixture, but also on the proportion that exists between them .

Thus, by adding more alloying material, certain characteristics of the base material will be further modified, to the detriment of others. This proportion, depending on the alloy, can vary between minimum percentages (0.2 to 2%) or much more noticeable within the mix.

Examples of alloys

  1. Steel . This alloy is essential for the construction industry, since it is used to make beams or supports for pouring concrete or concrete. It is a resistant and malleable material, mainly due to the alloy of iron and carbon, although it can also have silicon, sulfur and oxygen in even smaller proportions. The presence of carbon makes iron more resistant to corrosion and more brittle at the same time, so in rare cases it exceeds a very small percentage. According to the presence of this last element, a whole range of usable steels is obtained.
  2. Brass . This material is widely used in the container industry, especially for non-perishable food, as well as in domestic pipes and fittings. Obtained from copper and zinc alloy, it is highly ductile and malleable and shines easily when polished. According to the proportion between the elements, it is possible to obtain variants with various properties: more or less resistant to rust , more or less brittle, etc.
  3. Bronze . Bronze played a very important role in the history of humanity, as a material to make tools, weapons and ceremonial objects. Many bells were made with this material, as well as many coins, medals, national statues and various domestic implements, taking advantage of its enormous malleability and its economic obtaining from copper and tin.
  4. Stainless steel . This variant of ordinary steel (carbon steel) is prized for its extreme resistance to corrosion, making it ideal for making kitchenware, auto parts, and medical tools. To obtain this metal, chromium and nickel are used in alloy with the steel.
  5. Amalgam . In frank disuse due to its mercury content making it slightly toxic to the human body, this metallic filling used to be used as a dental sealant by dentists. It is the alloy of silver, tin, copper and mercury in a pasty substance that hardens as it dries out.
  6. Duralumin . Duralumin is a light and resistant metal that combines the properties of copper and aluminum, whose alloy it is a product. It is used in the aeronautical industry and in others that require a light, malleable and rust resistant material.
  7. Pewter . Product of the zinc, lead, tin and antimony alloy, it is a substance widely used in the elaboration of kitchen objects (cups, plates, pots, etc.) due to its extreme lightness and heat conduction. It is very malleable, a property that it undoubtedly receives from the unique elasticity of lead.
  8. White gold . Many jewels (rings, necklaces, etc.) and ornamental objects are made from so-called white gold: a very lustrous, shiny and precious metal that is obtained from alloying gold, copper, nickel and zinc. It is ideal for making jewelry less heavy than pure gold, and also allows you to use a smaller amount of this precious mineral , making objects more economical.
  9. Magnalio . Another metal highly demanded by the automotive and canning industries, since despite its low density it has hardness, toughness and tensile strength. It is obtained by alloying aluminum with a magnesium content (just 10%).
  10. Wood metal . This metal got its name from the dentist Barnabás Wood, its inventor, and is an alloy of 50% bismuth, 25% lead, 12.5% ​​tin and 12.5% ​​cadmium. Despite its toxicity, given the lead and cadmium it contains, it is used in melts and solders, releasing gases that should not be inhaled. Today, however, there are less toxic alternatives to use.
  11. Field metal . This alloy of bismuth (32.5%), indium (51%) and tin (16.5%) becomes liquid at 60 ° C, so it is used for industrial molding and prototyping, or as a non-toxic replacement Wood’s metal.
  12. Galinstano . One of the metals with which it has been tried to replace the uses of alloys with mercury (toxic), is this alloy of gallium, indium and tin. It is liquid at room temperature and is less reflective and less dense than mercury. It also has applications as a refrigerant.
  13. Rose metal . Also known as Rose Alloy, it is a metal widely used in solders and fusions, which in turn is the product of bismuth (50%), lead (25%) and tin (25%).
  14. NaK . An alloy of sodium (Na) and potassium (K) is known by this name, a highly oxidizing substance, capable of releasing large amounts of heat energy ( exotherm ). A few grams is sufficient, in contact with oxygen in the air is sufficient to cause a fire. Still, this alloy is liquid at room temperature and is used as a catalyst, coolant, or industrial desiccant.
  15. Vitalio . Refractory alloy of cobalt (65%), chromium (25%) and molybdenum (6%) as well as other minor elements (iron, nickel), was developed for the first time in 1932 and is very useful due to its lightness and extreme resistance to corrosion and temperature. They are made with vitalium surgical supplies, reaction turbines or combustion chambers.

 

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