Page 26 - Curriculum Visions Dynamic Book

Modern coins that look like silver are actually an alloy of 75% copper and 25% nickel.
A piece of jewellery made of pure gold is called 24-carat gold. Most jewellery is, however, an alloy. For example, the commonly used 18-carat gold is only 75% gold.
In industry many alloys are based on aluminium. Aluminium-magnesium-silicon alloys become stronger when they are heated because heating precipitates fine particles that lock the alloy together. They are also valued for their corrosion resistance. They are used, for example, in storm doors, window frames, truck cabs and trailers, boats, and “alloy” wheels of cars.
Aluminium-copper alloys are extremely strong but are not as corrosion resistant. They are used
in aircraft wings but have to be coated with aluminium to add corrosion resistance.
(Right)
Nickels, dimes, and quarters are all alloys designed to look like silver.
(Above) Fuses are alloys designed to have a low melting point.
(Above) This gold crown is not pure gold. It would be too soft. Rather, it is an alloy containing 60% gold, 22% silver, 12% copper, 4% palladium, and 1% zinc.
Porcelain crowns are supported by a silvery-white metal containing 57% palladium, 30% silver, 6% tin, and 2% zinc. These proportions achieve the best combination of no corrosion and strength in the porcelain.
(Below) This gold ring is actually an alloy and not pure gold. Pure gold
is soft and wears away easily.
(Below) This is sterling silver, an alloy with copper.
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