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Is called alloy to the process by which two or more elements, usually metallic, are combined into a single unit that gains the properties of both. Mostly alloys are considered mixtures, since the atoms of the combined components do not produce, except in rare cases, chemical reactions that intertwine their atoms.
Normally, the substances used in alloys are metallic: iron, aluminum, copper, lead, etc., but a metallic element with a non-metallic one: carbon, sulfur, arsenic, phosphorus, etc.
But nevertheless, the material resulting from the mixture always has metallic characteristics (shines, she drives heat and electricity, has more or less hardness, more or less malleability, more or less ductility, etc.), modified or strengthened with the additions of the other substance.
Types of alloys
It is usually distinguished between alloys based on the predominance of one element over others (for example, copper alloys), but also They are classified according to the amount of elements involved in the mixture, namely:
- Binary. They are made up of two elements (the base element and the alloying element).
- Ternary. They are made up of three elements (the base element and two alloys).
- Quaternary. They are composed of four elements (the base element and three alloys).
- Complex. They are made up of five or more elements (the base element and four or more alloys).
Another possible classification distinguishes between heavy and light alloys, according to the properties of the base metallic 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 mix, but also on the proportion that exists between them.
Thus, adding more alloying material will further modify certain characteristics of the base material, to the detriment of others. This proportion, depending on the alloy, can vary between minimal percentages (0.2 to 2%) or much more noticeable within the mixture.
Examples of alloys
- Steel. This alloy is essential for the construction industry, as it is used to make beams or supports for pouring concrete or concrete. It is a resistant and malleable material, product of the alloy of iron and carbon, mainly, although it can also have silicon, sulfur and oxygen in even smaller proportions. The presence of carbon makes the 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.
- Brass. This material is widely used in the container industry, especially those destined for non-perishable food, as well as in domestic pipes and taps. Obtained from the alloy of copper and zinc, it is extremely 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 oxide, more or less fragile, etc.
- Bronze. Bronze played a very important role in the history of mankind, as a material for making 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.
- 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 steel.
- Amalgam. In frank disuse due to its mercury content that makes it slightly toxic to the human body, this metal 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 when it dries.
- Duralumin. Duralumin is a light and resistant metal, which combines the properties of copper and aluminum, of whose alloy it is a product. It is used in the aeronautical industry and others that require a light, malleable and rust resistant material.
- Pewter. Product of the zinc, lead, tin and antimony alloy, it is a substance long used in the production 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.
- White gold. Many jewels (rings, necklaces, etc.) and ornamental objects are made from so-called white gold: a very lustrous, shiny and precious metal obtained by alloying gold, copper, nickel and zinc. It is ideal for making jewelery that is lighter than pure gold, and it also allows you to use less of this mineral precious, achieving cheaper objects.
- Magnalium. Another metal highly demanded by the automotive and canning industry, since despite its low density it has hardness, toughness and tensile strength. It is obtained by alloying aluminum with a magnesium content (just 10%).
- Wood's 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 welds, releasing gases that should not be inhaled. Today, however, there are less toxic alternatives to use.
- 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 of Wood's metal.
- 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.
- Rose Metal. Also known as Rose Alloy It is a metal widely used in welds and fusions, in turn a product of the alloy of bismuth (50%), lead (25%) and tin (25%).
- NaK. It is known by this name to an alloy of sodium (Na) and potassium (K), a highly oxidizing substance, capable of releasing large amounts of caloric energy (exothermic). A few grams are enough, in contact with the oxygen in the air they are enough to start a fire. Even so, this alloy is liquid at room temperature and is used as catalyst, refrigerant or industrial desiccant.
- Vital. Refractory alloy of cobalt (65%), chromium (25%) and molybdenum (6%) as well as other minor elements (iron, nickel), it was developed for the first time in 1932 and is very usable due to its lightness and extreme resistance to corrosion and temperature. They are manufactured with vital surgical supplies, reaction turbines or combustion chambers.
