Copper is one of the most useful metals known to man, and it was one of the first to be utilized. Copper is a reddish-yellow material and is extremely ductile. Copper has a face-centered-cubic (fcc) crystal structure and has the second best electrical conductivity of the metals, second only to silver compared to which it has a conductivity of 97%.
The thermal conductivity of copper is very high falling in between silver and gold. There are almost 400 different copper alloys depending on the commercial product made likes : rods, plates, sheets, strips, tubes, pipes, extrusions, foils, forgings, wires, and castings from foundries.
Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both these are imprecise terms, and today the term copper alloy tends to be substituted, especially by museums.
The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions.
There are as many as 400 different copper and copper-alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses, bronzes, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys.
Pure copper has the best electrical and thermal conductivity of any commercial metal. Copper forms alloys more freely than most metals and with a wide range of alloying elements to produce the following alloys :
The following table lists the principal alloying element for four of the more common types used in modern industry, along with the name for each type. Historical types, such as those that characterize the Bronze Age, are vaguer as the mixtures were generally variable.
A brass is an alloy of copper with zinc. Brasses are usually yellow in color. The zinc content can vary between few % to about 40%; as long as it is kept under 15%, it does not markedly decrease corrosion resistance of copper.
Brasses can be sensitive to selective leaching corrosion under certain conditions, when zinc is leached from the alloy (dezincification), leaving behind a spongy copper structure.
The diagram shows the structure of binary copper-zinc alloys when fully in equilibrium, indicating the preferred temperatures for stress relieving, full annealing and hot working. The differences in the properties of the phases are partly due to the fact that alpha brass has a face-centered cubic structure while beta brass is body-centered cubic.
Copper tin phase diagram showing a peritectic point. The peritectic reaction is an important example of a microstructural transformation. Sn – 21wt.%Cu exhibits this transformation from a solid phase and a liquid phase to a different, solid phase.
A bronze is an alloy of copper and other metals, most often tin, but also aluminium and silicon.
Copper application areas cover a wide variety of different disciplines.