Abstract: 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.

Abstract: 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 NiP-based alloy and plated on the surface of the substrate. The film has a thickness of 7 ?m or greater, and a ratio E/? is 29 or greater, where E [GPa] denotes the Young's modulus of the substrate, and ? [g/cm3] denotes a density of the substrate.

Abstract: An aluminum alloy substrate for a magnetic recording medium, the substrate including: Si in a range of 9.5 to 13.0% by mass or less and Cu in a range of 0.5 to 3.0% by mass or less, wherein a content of Fe is less than 0.01% by mass, the balance is Al, the substrate has a diameter in a range of 53 to 97 mm and a thickness in a range of 0.4 to 0.9 mm or less, and the substrate satisfies at least one of the following conditions (i) and (ii): (i) Sr is contained in the substrate in a range of 0.005% by mass or more and 0.1% by mass or less; and (ii) at least a part of the Si is present as Si particles, and an average particle diameter of particles having a longest diameter of 0.5 ?m or more among the Si particles is 2 ?m or less.

Abstract: 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 NiP-based alloy and plated on the surface of the substrate. The film has a thickness of 7 ?m or greater, and a ratio E/? is 29 or greater, where E [GPa] denotes the Young's modulus of the substrate, and ? [g/cm3] denotes a density of the substrate.

Abstract: A base for a magnetic recording medium includes, a substrate made of an Al alloy, and a film made of a NiP-based alloy and provided on the substrate. The Al alloy of the substrate includes Mg in a range of 0.2 mass % to 6 mass %, Si in a range of 3 mass % to 17 mass %, Zn in a range of 0.05 mass % to 2 mass %, and Sr in a range of 0.001 mass % to 1 mass %. An average grain diameter of Si grains in an alloy structure of the substrate is 2 ?m or less. The film has a thickness of 10 ?m or greater. The substrate has an outer diameter of 53 mm or greater, a thickness of 0.9 mm or less, and a Young's modulus of 79 GPa or higher.

Abstract: 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.

Abstract: A base for a magnetic recording medium includes, a substrate made of an Al alloy, and a film made of a NiP-based alloy and provided on the substrate. The Al alloy of the substrate includes Mg in a range of 0.2 mass % to 6 mass %, Si in a range of 3 mass % to 17 mass %, Zn in a range of 0.05 mass % to 2 mass %, and Sr in a range of 0.001 mass % to 1 mass %. An average grain diameter of Si grains in an alloy structure of the substrate is 2 ?m or less. The film has a thickness of 10 ?m or greater. The substrate has an outer diameter of 53 mm or greater, a thickness of 0.9 mm or less, and a Young's modulus of 79 GPa or higher.