Which statement regarding copper alloys with more than 70% copper is true?

Copper alloys that contain more than 70% copper exhibit natural antifouling properties. This characteristic arises from the biocidal effects of copper, which inhibits the growth of marine organisms such as barnacles, algae, and other fouling species. As a result, components made from these alloys can help maintain the cleanliness and efficiency of marine vessels and structures, making them advantageous for use in marine environments.

The other options do not accurately reflect the properties and applications of high-copper alloys. For instance, while copper alloys are not suitable for every marine application, they are not universally unsuitable, and their high copper content does not preclude their use in heat exchangers; in fact, they can often be quite effective in such applications due to their thermal conductivity. Moreover, the assertion that they must maintain antifouling doesn’t accurately capture the effectiveness of these materials since the antifouling properties are inherent rather than a requirement that needs to be upheld. Thus, recognizing the natural antifouling qualities of copper alloys is crucial for understanding their role and benefits in marine applications.