Cupronickel (sometimes incorrectly written as Cupernickel) or Coppernickel's an alloy of copper, nickel and strengthening impurities, such as iron and manganese. Cupronickel doesn't corrode in seawater, because its electrode potential's adjusted to be neutral with regard to seawater. Because of this it's used for marine hardware, and sometimes for the propellers, crankshafts and hulls of premium tugboats, fishing boats and other working boats. A common use's in many silver-coloured modern circul… (More on Cupronickel)