Eureka vs copper-base alloy

Eureka and copper-base alloy both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eureka	Yes	No	No	No
copper-base alloy	Yes	No	No	No

As nouns, copper-base alloy is a hypernym of Eureka; that is, copper-base alloy is a word with a broader meaning than Eureka:

Eureka: an alloy of copper and nickel with high electrical resistance and a low temperature coefficient; used as resistance wire
copper-base alloy: any alloy whose principal component is copper

Eureka (noun)	copper-base alloy (noun)
a town in northwest California on an arm of the Pacific Ocean	any alloy whose principal component is copper
an alloy of copper and nickel with high electrical resistance and a low temperature coefficient; used as resistance wire