A corrosion resistant perpendicular magnetic recording medium comprises: (a) a non-magnetic substrate having a surface; and (b) a layer stack formed over the substrate surface and comprising, in overlying sequence from the surface: (i) a magnetically soft underlayer (SUL); (ii) at least one non-magnetic interlayer; and (iii) at least one magnetically hard perpendicular recording layer; wherein the SUL comprises an FeCo-based alloy material having a composition selected to provide: (1) a substantially amorphous microstructure with a smooth surface in contact with the non-magnetic interlayer; (2) high saturation magnetization Ms greater than about 1.6 T; and (3) corrosion resistance.