Alloys - Bronze

The place and time of the invention of bronze are controversial, and it is possible that bronzing was invented independently in multiple places.

The earliest known tin bronzes are from Iran and Iraq and date to the late 4th millennium BC, but there are claims of an earlier appearance of tin bronze in Thailand in the 5th millennium BC.

Arsenical bronzes were made in Anatolia and on both sides of the Caucasus by the early 3rd millennium BC. Some scholars date some arsenical bronze artefacts of the Maykop culture in the North Caucasus as far back as the mid 4th millennium BC, which would make them the oldest known bronzes, but others date the same Maykop artefacts to the mid 3rd millennium BC.

In Great Britain, the Bronze Age is considered to have been the period from around 2100 to 700 BC.

Immigration brought new people to the islands from the continent. Recent tooth enamel isotope research on bodies found in early Bronze Age graves around Stonehenge indicate that at least some of the immigrants came from the area of modern Switzerland.

The Beaker people displayed different behaviours from the earlier Neolithic people and cultural change was significant. Integration is thought to have been peaceful as many of the early henge sites were seemingly adopted by the newcomers.

The rich Wessex culture developed in southern Britain at this time. Additionally, the climate was deteriorating, where once the weather was warm and dry it became much wetter as the Bronze Age continued, forcing the population away from easily-defended sites in the hills and into the fertile valleys.

Large livestock ranches developed in the lowlands which appear to have contributed to economic growth and inspired increasing forest clearances.

The Deverel-Rimbury culture began to emerge in the second half of the 'Middle Bronze Age' (c. 1400-1100 BC) to exploit these conditions.

Cornwall was a major source of tin for much of western Europe and copper was extracted from sites such as the Great Orme mine in northern Wales. Social groups appear to have been tribal but with growing complexity and hierarchies becoming apparent.

Alloys - Brass

Brass is the term used for alloys of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses each with unique properties[1]. Note that in comparison bronze is principally an alloy of copper and tin.[2]. Despite this distinction, some types of brasses are called bronzes. Brass is a substitutional alloy.

Brass has a yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration.

Brass has been known to humans since prehistoric times, long before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. During this process, the zinc is extracted from the calamine and mixes with the copper. Pure zinc, on the other hand, is too reactive to have been produced by ancient metalworking techniques. Brass is mainly used for decorative, plumbing and electrical applications
 

The malleability and acoustic properties of brass have made it the metal of choice for brass musical instruments such as the trombone, tuba, trumpet and euphonium. Even though the saxophone is classified as a woodwind instrument and the harmonica is a free reed aerophone, both are also often made from brass. In organ pipes designed as "reed" pipes, brass strips are used as the "reed".

Brass has higher malleability than copper or zinc. The relatively low melting point (900–940 °C depending on composition) of brass and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.

Today almost 90% of all brass alloys are recycled. Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are later heated up and extruded into the right form and size.

Aluminum makes brass stronger and more corrosion resistant. Aluminum also causes a highly beneficial hard layer of aluminium oxide (Al2O3) to be formed on the surface that is thin, transparent and self healing. Tin has a similar effect and finds its use especially in sea water applications (naval brasses). Combinations of iron, aluminum, silicon and manganese make brass wear and tear resistant. A well known alloy used in the automotive industry is 'LDM C673', where the right combination of manganese and silicon lead to a strong and resistant brass.

Brass was used to make fan blades, fan cages and motor bearings in many antique fans that date before the 1930s.

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