Abstract: The present invention intends to provide a magnetic disk that is flat while being thin and hardly causes physical errors. The present invention provides a magnetic disk having a hole in the center, a thickness of 0.60 mm or less, TIRs on circles having different radial distances r1 (mm) and r2 (mm) denoted by TIR1 (?m) and TIR2 (?m), and an amount of radial variation ?TIR for TIRs of 0.50 ?m/mm or less in an outer circumferential region of the magnetic disk with r/R=0.70 to 0.99, where “R” is a disk radius (mm), “r” is a radial distance (mm) measured from the disk center, and the ?TIR is represented by an absolute value |(TIR1?TIR2)/(r1?r2)| of the ratio of the difference (TIR1?TIR2) between the TIR1 and the TIR2 to the difference (r1?r2) between r1 and r2 of the magnetic disk.

Abstract: An aluminum alloy substrate for a magnetic disc is made of an aluminum alloy, containing Fe: 1.80 mass % or less, Mn: 0.70 mass % or less, Ni: 2.50 mass % or less, Si: 2.50 mass % or less, Cu: 1.00 mass % or less, Zn: 0.48 mass % or less and Mg: 1.00 to 3.50 mass %, wherein a total content of Fe, Mn and Ni is 1.60 to 4.50 mass % and a mass ratio of Cu/Zn is 0.01 to 0.35 or 6.00 to 50.00, with a balance being Al and inevitable impurities.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks, a spacer, a hub, and a clamp. Each of the magnetic disks includes a through-hole in a center section thereof. The spacer is disposed among the magnetic disks, and includes a through-hole in a center section thereof. The hub is inserted into the through-holes of the magnetic disks and the spacers. The clamp presses and holds the magnetic disks and the spacer. At surfaces where the magnetic disks and the spacer or the clamp contact, a flat surface height of an upper surface of at least one magnetic disk that contacts an outer circumference of the spacer or the clamp is lower than a flat surface height of the upper surface of at least one magnetic disk of the magnetic disks that contacts an inner circumference of the spacer or the clamp.

Abstract: An example method for producing an aluminum alloy raw material, wherein in a separation step of reusing, as a recycled material, at least one of an intermediate material and a finished product each comprising an aluminum alloy disk and an underlayer, for at least part of an aluminum alloy material and heating the aluminum alloy material comprising the recycled material to separate the aluminum alloy disk and the underlayer, and the aluminum alloy material comprising the recycled material is heated and held at 480° C. or higher and 590° C. or lower for more than 1 hour.

Abstract: The purposes of the present invention are to provide a substrate for a magnetic disk and a disk capable of maintaining long-term reliability of a hard disk while dealing with an increase in capacity of the hard disk and to provide a manufacturing method by which a magnetic disk (substrate therefor) having the above-mentioned characteristic can be manufactured. The present invention pertains to: a magnetic disk (substrate therefor) having a pair of main surfaces, wherein a 0.4 to 5.0 mm cutoff wavelength of at least one of the main surfaces of the magnetic disk (substrate therefor) at 25° C. after a predetermined thermal shock test has long wavelength waviness Wa of 2.0 nm or less, especially 0.5 to 2.0 nm, and a 0.08 to 0.45 mm cutoff wavelength thereof has short wavelength waviness ?Wa of 0.15 nm or less, especially 0.05 to 0.15 nm; and a manufacturing method thereof.

Abstract: A magnetic disk substrate having a pair of front and back principal surfaces, containing fixed portions that are in contact with fixing jigs when the magnetic disk substrate configured as a magnetic disk is incorporated in a hard disk device on the respective front and back principal surfaces, wherein a root mean square deviation Rq of surface roughnesses of the fixed portions on the respective front and back principal surfaces is from 0.01 to 0.44 ?m.; and a magnetic disk using the same.

Abstract: 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.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks 30, spacers 80, a hub 90, a clamp 70, and a fastening member 72. Each of the magnetic disks 30 includes a through-hole in a center section thereof. Each of the spacers 80 includes a through-hole in a center section thereof, and is disposed among the magnetic disks 30. The hub 90 is inserted into the through-holes of the magnetic disks 30 and the spacers 80. The clamp 70 presses and holds the magnetic disks 30 and the spacers 80. The fastening member 72 fastens the clamp 70 to the hub 90. The clamp 70 is fastened to the hub by the fastening member 72 with a torque of from 5 cN·m to 45 cN·m.

Abstract: An example thin substrate built-in hard disk drive includes a magnetic disk in a disk shape having a through-hole at the center, a spindle motor inserted into the through-hole of the magnetic disk and co-rotatably supporting the magnetic disk, and a base plate made of an aluminum alloy and supporting the spindle motor. The base plate has a metallographic structure in which a perimeter of a second phase particle having a longest diameter of 10 ?m or more is 3 mm/mm2 or more, and the number of second phase particles having a longest diameter of 500 ?m or more is 0 particles/mm2.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks, a spacer, a hub, and a clamp. Each of the magnetic disks includes a through-hole in a center section thereof. The spacer is disposed among the magnetic disks, and includes a through-hole in a center section thereof. The hub is inserted into the through-holes of the magnetic disks and the spacers. The clamp presses and holds the magnetic disks and the spacer. At surfaces where the magnetic disks and the spacer or the clamp contact, a flat surface height of an upper surface of at least one magnetic disk that contacts an outer circumference of the spacer or the clamp is lower than a flat surface height of the upper surface of at least one magnetic disk of the magnetic disks that contacts an inner circumference of the spacer or the clamp.

Abstract: A magnetic disk device includes a plurality of disk-shaped magnetic disks 30, spacers 80, a hub 90, a clamp 70, and a fastening member 72. Each of the magnetic disks 30 includes a through-hole in a center section thereof. Each of the spacers 80 includes a through-hole in a center section thereof, and is disposed among the magnetic disks 30. The hub 90 is inserted into the through-holes of the magnetic disks 30 and the spacers 80. The clamp 70 presses and holds the magnetic disks 30 and the spacers 80. The fastening member 72 fastens the clamp 70 to the hub 90. The clamp 70 is fastened to the hub by the fastening member 72 with a torque of from 5 cN·m to 45 cN·m.

Abstract: An example thin substrate built-in hard disk drive includes a magnetic disk in a disk shape having a through-hole at the center, a spindle motor inserted into the through-hole of the magnetic disk and co-rotatably supporting the magnetic disk, and a base plate made of an aluminum alloy and supporting the spindle motor. The base plate has a metallographic structure in which a perimeter of a second phase particle having a longest diameter of 10 ?m or more is 3 mm/mm2 or more, and the number of second phase particles having a longest diameter of 500 ?m or more is 0 particles/mm2.

Abstract: This magnetic disk device is a 3.5-inch magnetic disk device equipped with magnetic disks formed from an aluminum alloy substrate. The magnetic disks arranged in a stacked manner have a thickness Td of 0.3 mm to 0.6 mm, the number N of magnetic disks involved is 10 to 16, and spacers disposed between the magnetic disks have an outside diameter 2 Rso of 35 mm to 65 mm. The outside diameter 2 Rso (mm) of the spacers satisfies 2 Rso??60 Td+70 and 2 Rso??0.5 N2?+16.5 N?73.

Abstract: An aluminum alloy substrate for a magnetic disc is made of an aluminum alloy, containing Fe: 1.80 mass % or less, Mn: 0.70 mass % or less, Ni: 2.50 mass % or less, Si: 2.50 mass % or less, Cu: 1.00 mass % or less, Zn: 0.48 mass % or less and Mg: 1.00 to 3.50 mass %, wherein a total content of Fe, Mn and Ni is 1.60 to 4.50 mass % and a mass ratio of Cu/Zn is 0.01 to 0.35 or 6.00 to 50.00, with a balance being Al and inevitable impurities.

Abstract: An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy containing Mg: 3.40 to 3.90 mass % with the balance being A1 and inevitable impurities, wherein a conductivity of the aluminum alloy disc blank is 36.0% IACS or higher.

Abstract: A hard disk drive is a 3.5-inch hard disk drive on which a magnetic disk formed of an aluminum alloy substrate is mounted. A thickness Td of each of magnetic disks that are arranged in a stacked manner is 0.3 mm or more and 0.6 mm or less, the number N of the magnetic disks is 10 or more and 16 or less, and an outer diameter 2Rso of a spacer that is arranged between the magnetic disks is 35 mm or more and 65 mm or less. The outer diameter 2Rso (mm) of the spacer satisfies 2Rso??60Td+70 and 2Rso??0.5N2+16.5N?73.

Abstract: A magnetic disk substrate includes an aluminum alloy including one type or two or more types of Fe: 8.5 mass % or less, Mn: 2.5 mass % or less, Ni: 6.5 mass % or less, and Mg: 4.5 mass % or less, a balance being Al and unavoidable impurities, wherein, when f (Hz) is a resonance frequency, ? (g/cm3) is a density, and t (mm) is a plate thickness, (f×?/t) is 3800 or greater; and a magnetic disk using the magnetic disk substrate.

Abstract: An aluminum alloy substrate for magnetic disks, including an aluminum alloy containing: 1.0 to 6.5 mass % of Mg; and the balance consisting of Al and unavoidable impurities, in which the distribution of Si—K—O-based particles with a longest diameter of 1 ?m or more adhering to the surface from the surrounding environment is equal to or less than one particle/6,000 mm2; and in which the distribution of Ti—B-based particles with a longest diameter of 1 ?m or more present on the surface is equal to or less than one particle/6,000 mm2, and a magnetic disk using the aluminum alloy substrate for magnetic disks.

Abstract: An aluminum alloy substrate for magnetic disks, including an aluminum alloy containing Fe as an essential element; at least one of Mn or Ni as selective elements; and the balance including Al and unavoidable impurities, with the total amount of Fe, Mn, and Ni having a relationship of 0.10 to 7.00 mass %; in which the distribution of Si—K—O-based particles with a longest diameter of 1 ?m or more adhering to the surface from the surrounding environment is equal to or less than one particle/6,000 mm2, and in which the distribution of Ti—B-based particles with a longest diameter of 1 ?m or more present on the surface is equal to or less than one particle/6,000 mm2; and a magnetic disk using the aluminum alloy substrate.

Abstract: An aluminum alloy substrate for a magnetic disk including an aluminum alloy containing 0.1 to 3.0 mass % of Fe, 0.005 to 1.000 mass % of Cu, and 0.005 to 1.000 mass % of Zn, with a balance of Al and inevitable impurities, wherein in an outer peripheral surface thereof, the number of holes having maximum diameters of 10 ?m or more is 200/mm2 or less, an aluminum alloy base disk for a magnetic disk and a magnetic disk, using the aluminum alloy substrate, and methods for manufacturing these.