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Which metals are alloys

Metal alloys are homogeneous mixtures of metals. In them, no chemical reaction takes place and, therefore, no new chemical compounds are formed. In addition, each alloy adds the properties of the different components of the mixture.

This process is a physical method of combining metals or metals and non-metals, carried out at high temperatures. In this way, new metals are obtained.


Types of alloys

Depending on the metals that are alloyed, we can distinguish two types of metal alloys.

Ferrous metal alloys

Ferrous alloys stand out as those that have iron as their main element. This group includes steels, which are obtained by mixing iron with varying amounts of carbon and others. The combination of iron and cobalt also gives rise to alloys known as alnico, used in the manufacture of permanent magnets.

Non-ferrous metal alloys

These alloys are made of metals other than iron and offer different properties and applications. The most common are aluminium alloys, which are notable for their low weight, high corrosion resistance and good thermal conductivity.

Copper is also used to form non-ferrous alloys, as is zinc.

Popular metal alloys


Steel is considered an alloy of iron if it contains less than 2.1% carbon. If that percentage is higher, it is called cast iron.

Steel has the metallic characteristics of iron in its pure state, but the addition of carbon and other metallic or non-metallic elements improves its physicochemical properties, especially its strength. They are classified according to their carbon content: low carbon steels (<0.25%), medium carbon steels (0.25%-0.6%), high carbon steel (0.6%-1.4%) and alloy steels (carbon + other elements).


Bronze is an alloy composed of copper (the base alloy) and tin (which makes up 3-20%). It can also include other metals, achieving different properties in the material. The differences between copper and bronze, although they appear very similar, are significant and the two must be distinguished.

Current applications include its use in mechanical parts resistant to friction and corrosion, in good quality musical instruments such as bells, gongs, cymbals, saxophones, and in the manufacture of strings for harps, guitars and pianos.


Brass is an alloy composed of copper and zinc. Different varieties of this metal can be created depending on the proportion of its composition, as well as different properties.

Brass is produced when copper is fused with calamine, a zinc mineral. In the melting process, the zinc is extracted from the calamine and mixed with the copper. Other materials may also be added. It has a colour similar to gold. Moreover, because it contains almost no iron in its composition, it is one of the metals that does not rust.


Constantan is an alloy, generally consisting of 55% copper, 45% nickel and a small amount of manganese. It is characterised by a constant electrical resistance over a wide temperature range and is one of the most commonly used materials for coin making.


Duralumin is an alloy of aluminium with copper, manganese, magnesium and silicon. It belongs to the family of aluminium-copper alloys.

It is a very strong aluminium alloy, widely used in the aircraft industry and other construction sectors where very high mechanical strength and corrosion resistance are required.

Stainless steel

Stainless steel is an alloy of steel containing at least 10-12% chromium, although it may also contain other metals such as nickel, aluminium, tungsten or molybdenum. The chromium reacts with oxygen to create a layer of chromium oxide called a passive layer. This prevents the reaction between iron and oxygen and therefore makes the steel highly resistant to atmospheric corrosion and rust.

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