Copper nickel or fachsprachlich correctly copper-nickel alloy castings are cast alloys with copper as the main component ( copper alloys ), and nickel contents of 10, 20 or 30%. A low silicon content is permissible. The alloys are characterized by high corrosion resistance, even against sea water .
Because of their decorative appearance, utensils and ornaments are often made from such alloys.
Copper was already used as a material for coins in antiquity , but pure nickel was not yet available because of its high melting point, even though the raw copper-nickel stone was already known. Silver and gold were used for valuable coins. Copper already takes on a silvery color with a nickel content below 15%. Around 1960–2000, coins made of a copper-nickel alloy largely replaced the silver coins that had been used up until then for higher denominations.
In the case of euro coins , the alloy CuNi25 is used both for the ring of the 2 euro coin and for the core of the 1 euro coin (known as the pill ), which consists of nickel coated on both sides with CuNi25. The Swiss circulation coins from ten centimes to five francs are also made of this alloy.
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