A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiWP-based alloy and plated on the surface of the substrate. The film includes W in a range of 15 mass % to 22 mass %, P in a range of 3 mass % to 10 mass %, and Pb in a range of 0.03 mass % to 0.08 mass %. The film has a thickness of 5 m or greater.

A base for a magnetic recording medium, includes a substrate made of an Al alloy and having a surface, and a film made of a NiWP-based alloy and plated on the surface of the substrate. The film includes W in a range of 15 mass % to 22 mass %, P in a range of 3 mass % to 10 mass %, and Pb in a range of 0.03 mass % to 0.08 mass %. The film has a thickness of 5 m or greater.

A magnetic recording medium substrate is provided in which a NiP type plating film is formed on a surface of an aluminum alloy substrate that includes Si in a range of 9.5 mass % or more and 11.0 mass % or less, Mn in a rage of 0.45 mass % or more and 0.90 mass % or less, Zn in a range of 0.32 mass % or more and 0.38 mass % or less, Sr in a range of 0.01 mass % or more and 0.05 mass % or less. In the alloy structure of the aluminum alloy substrate, an average particle diameter of Si particles is 2 m or less, the film thickness of the NiP type plating film is 7 m or more. An outer diameter of the magnetic recording medium substrate is 53 mm or more, the thickness is 0.9 mm or less, and the Young's modulus is 79 GPa or more.

A magnetic recording medium substrate is provided in which a NiP type plating film is formed on a surface of an aluminum alloy substrate that includes Si in a range of 9.5 mass % or more and 11.0 mass % or less, Mn in a rage of 0.45 mass % or more and 0.90 mass % or less, Zn in a range of 0.32 mass % or more and 0.38 mass % or less, Sr in a range of 0.01 mass % or more and 0.05 mass % or less. In the alloy structure of the aluminum alloy substrate, an average particle diameter of Si particles is 2 m or less, the film thickness of the NiP type plating film is 7 m or more. An outer diameter of the magnetic recording medium substrate is 53 mm or more, the thickness is 0.9 mm or less, and the Young's modulus is 79 GPa or more.

A data storage device comprising a recording head having a high damping magnetic alloy layer including at least one magnetic alloy element, and a 5d transition element; the high damping magnetic alloy layer having a mixed face-centered cubic (fcc) and body-centered cubic (bcc) crystal structure, and the mixed fcc and bcc crystal structure comprising fcc and bcc grains, with the bcc grains having an elongated shape relative to the fcc grains, a larger size than the fcc grains, and slip deformation, thereby providing the high damping magnetic alloy layer with a damping constant of up to about 0.07.

Provided are a thin hard disk substrate that is scratch-resistant on the disk surface and wobbles less during rotation and a hard disk device including such a hard disk substrate. The hard disk substrate 1 includes an aluminum alloy substrate 2 having NiP plating films 3 on the surfaces. The aluminum alloy substrate 2 has the Vickers hardness of 60 Hv or more, the ratio between the thickness of the NiP plating films 3 and the thickness of the Al alloy substrate 2 is 3.8% or more, the Young's modulus of the hard disk substrate 1 is 74.6 GPa or more, and the Vickers hardness of the hard disk substrate 1 is 293 Hv or more.

A method includes immersing a wafer in an electrolyte including a plurality of compounds having elements of a high damping magnetic alloy with very low impurity and small uniform grain size. The method also includes applying a pulsed current with a certain range of duty cycle and pulse length to the wafer when the wafer is immersed in an electrolyte. The wafer is removed from the electrolyte when a layer of the high damping magnetic alloy is formed on the wafer.

Embodiments described herein provide methods and apparatus for treating a magnetic substrate having an imprinted, oxygen-reactive mask formed thereon by implanting ions into a magnetically active surface of the magnetic substrate through the imprinted oxygen-reactive mask, wherein the ions do not reduce the oxygen reactivity of the mask, and removing the mask by exposing the substrate to an oxygen-containing plasma. The mask may be amorphous carbon, through which carbon-containing ions are implanted into the magnetically active surface. The carbon-containing ions, which may also contain hydrogen, may be formed by activating a mixture of hydrocarbon gas and hydrogen. A ratio of the hydrogen and the hydrocarbon gas may be selected or adjusted to control the ion implantation.

Embodiments described herein provide methods and apparatus for treating a magnetic substrate having an imprinted, oxygen-reactive mask formed thereon by implanting ions into a magnetically active surface of the magnetic substrate through the imprinted oxygen-reactive mask, wherein the ions do not reduce the oxygen reactivity of the mask, and removing the mask by exposing the substrate to an oxygen-containing plasma. The mask may be amorphous carbon, through which carbon-containing ions are implanted into the magnetically active surface. The carbon-containing ions, which may also contain hydrogen, may be formed by activating a mixture of hydrocarbon gas and hydrogen. A ratio of the hydrogen and the hydrocarbon gas may be selected or adjusted to control the ion implantation.

An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy containing Fe: 0.005 to 1.800 mass % with the balance being Al and inevitable impurities, wherein a flatness change of the aluminum alloy disc blank for a magnetic disc when the aluminum alloy disc blank for a magnetic disc is held in the atmosphere at 50? C. or lower for 336 hours is 2.0 ?m or less.