Metal used in a nickel coin?

erm....nickel

Not quite ...

US nickels are actually made from an alloy of only 25% nickel, the rest is copper.

Canadian nickels were once pure nickel, but in recent years they've been made of steel because the price of nickel rose to the point where the amount needed would cost more than five cents.

Copper. The mix is 75% copper and 25% nickel.