Bi-Metallic

From Wikipedia

Bi-metallic coins are coins consisting of more than one metal or alloy, generally arranged with an outer ring around a contrasting center. Common circulating examples include the €1, €2, British £2,Canadian $2,South African R5, and Turkish lira,1/5 dinar Libyan
Bi-metallic coins have been issued for a long time, with examples known dating from the 1600s, while the Roman Empire issued special occasion, large medallions with a center of bronze or copper and an outer ring of orichalcum, starting with the reign of Hadrian. The silver-center cent pattern produced by the United States in 1792 is another example. In recent times, the first circulating bi-metallic coin was the 500 Italian lire, first issued in 1982. France, with a 10 franc coin and Thailand, with a 10 baht, issued bi-metallic coins for circiraulation in 1988. India has released 10 Rupee bimetallic coins in 2009 that contains dateline of 2006 (minted at Noida) .

 

As well as circulating coins, where they are generally restricted to high denomination coins, bi-metallic coins are often used in commemorative issues, they are used as a way of securing against coin counterfeiting.
The manufacturing process is similar to that of ordinary coins, except that two blanks (the inner and the outer) are struck at the same time, deforming the separate blanks sufficiently to hold them together.