Titanium or titanium-alloy substrate for magnetic-recording media

A magnetic-recording disk comprising:

• a disk-shaped substrate composed of titanium or a titanium alloy;
• a hard material applied coating overlying a surface of the substrate, wherein the hard material coating is aluminum nitride, silicon nitride, silicon carbide, or a nitride, carbide, or boride of a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten, and is applied prior to the application of the magnetic-recording material, and wherein the hard material coating has a thickness of at least 0.5 micrometers;
• and
• a coating of a magnetic-recording material overlying the hard material coating.