Simplify the following text for a Grade 4 native English-speaking person.
Original: Nickel is pre-eminently an alloy metal , and its chief use is in the nickel steels and nickel cast irons , of which there are many varieties . It is also widely used in many other alloys , such as nickel brasses and bronzes , and alloys with copper , chromium , aluminium , lead , cobalt , silver , and gold .
Simplified: Nickel is used in metal alloys .