nickel alloy vs nickel-base alloy

nickel alloy and nickel-base alloy both are nouns.

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

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

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

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