What is the composition of cupronickel? Copper Nickel Alloys
In principle, a cupronickel can contain between 1% and 49% nickel, such that copper remains the main element (otherwise you would call it a nickel-copper alloy). Both elements are completely soluble in each other, which supports this very wide range of compositions.
The most commonly produced cupronickel is the 90/10 (90% Cu, 10% Ni). Increasing the nickel content towards 30% (alloys such as UNS C71640) will increase the abrasion resistance, which will also apply to the flowrates in seawater that parts may be exposed to.
Hiduron 130 (DTD 900/4805, 2.1504) and Hiduron 191 (DEFSTAN 02-835, NES835) both contain c.15% nickel, which is an optimum level to achieve excellent mechanical and physical properties. Both alloys have been used successfully for >50 years since their original development for naval applications, although today they are used in more varied applications such as subsea connectors, valve trim, fasteners and couplings, generally in seawater.