not sure that the whole leg is made of that though, but definitely the props and I think some of the outer casing on the lower part of the leg. Rams are stainless though.
The propellers for the DP drive are made of nickel-aluminium-bronze alloy – a common material in propellers for inboard installations. Volvo Penta is the first to use this material in propellers for a sterndrive. The primary advantages are that it permits the manufacture of high-precision propellers and is able to cope with high engine output. Corrosion resistance is also excellent with full electric isolation in the propellers.
Its a pity they didn't make the leg as corrosion resistant, we have changed many legs after only a few months due to serious corrosion, also there is a recall on the steering cylinders which seem to vanish quicker than the anodes!
Makes Bravo drives look very good in comparison ...