Magnetic recording disk and its production

PURPOSE: To obtain a metal alloy magnetic recording disk for contact recording by successively forming a nickel oxide film, a lower layer and a magnetic layer containing a cobalt alloy on a aluminum alloy substrate having a nickel- phosphorus surface coating. CONSTITUTION: A Ni-P coating film 62 after superfinishing process having no roughness on an aluminum alloy substrate 61 is oxidized to form a NiO coating film 64. By forming the NiO film 64, magnetic layers 66, 67 containing cobalt alloy to be formed by sputtering have extremely high saturation coercive force, and thereby, the obtd. disk can be used for a contact recording system. The layers which constitute the disk conform to the surface of the polished NiP, and therefore, the upper layer of the disk for a contact recording type disk file has an extremely smooth surface.