nickel-base alloy vs nickel alloy

nickel-base alloy and nickel alloy both are nouns.

Word	Noun	Adjective	Verb	Adverb
nickel-base alloy	Yes	No	No	No
nickel alloy	Yes	No	No	No

As nouns, nickel-base alloy and nickel alloy are synonyms defined as:

nickel-base alloy and nickel alloy: an alloy whose main constituent is nickel

nickel-base alloy (noun)	nickel alloy (noun)
an alloy whose main constituent is nickel	an alloy whose main constituent is nickel