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Alloys

Bronze and brass, the first alloys in the history of metallurgy, were probably obtained by man accidentally when melting mixed metal ores. Much later alloys of iron were obtained.

Steel was made in small quantities in early times un­til the mid-19th century when it was manufactured on a large scale in the iron and steel industry.

The commercial production of pure aluminium in about 1890 began a new range of alloys and among them duralumin, an alloy of about 94 per cent aluminium, with small quantities of copper, manganese, magnesium, and silicon. Most of aluminium alloys are both light and strong.

Nickel is often mixed with other metals for special purposes: permalloy is a nickel-iron alloy that is mag­netically soft. The polarity of its magnetic field can be easily changed and it is used for transformer cores. Monel metals contain about two parts nickel to one part cop­per, plus other elements. They are stronger than nickel and extremely corrosion-resistant. These properties make them useful in chemical production.

Electrum is a natural or artificial alloy of gold and sil­ver containing 15-45 per cent of silver. It was used in the ancient world for coinage.

Bismuth is frequently used as a part of alloys with low melting-points. Today alloys can be designed for particu­lar applications with certain properties.