It depends on the country. For a long time Canadian nickels were made of 99% nickel. However in the US the nickel only has 25% nickel in it and the rest is copper.
The 'copper' (1p & 2p coins) are made from 97% copper - and 3& trace elements. The 'silver' coins are made from nickel-plated sheet steel.
Nickel
Cupronickel or copper-nickel or "cupernickel" is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese.
Coins today are typically made of a combination of metal alloys, such as copper, nickel, and zinc. Different denominations may have different compositions to ensure durability and cost-effectiveness. Some countries are also exploring alternative materials like polymer or composite materials for their coins.
Copper - nickel
British coins of copper appearance, the 1 and 2 Pence coins, are made from copper plated steel. British coins of silver appearance, the cupro-nickel 5, 10 and 50 Pence coins, are made from 75% copper and 25% nickel. British 20 Pence coins, are made from 84% copper and 16% nickel.
The Iraqi coins made for general use since 1960 are made of nickel, copper-nickel, stainless steel, copper plated steel and nickel plated steel.
U.S. coins used to be made with silver, typically a blend of 90% silver with 10% copper. Then modern dimes, quarters, and half dollars are nickel-coated copper. Nickels are made with 25% nickel and 75% copper. There aren't any coins made of a silver/nickel blend.
two pound coins are made out of copper/zinc/brass/and nickel not gold
Today in 2012 the series of coin that we presently use is the contemporary coins where coins are made up of copper+nickel (cupro-nickel alloy).
For the same reason any other nickel was made - to provide coins for commerce.
Copper, Nickel, Silver and Gold