Aluminum alloy substrate for magnetic disks, method for producing same, and magnetic disk using this aluminum alloy substrate for magnetic disks

An aluminum alloy substrate for a magnetic disk, comprising an aluminum alloy consisting of:

• 0.4 to 3.0 mass % of Fe,
• 0.1 to 6.0 mass % of Mg,
• greater than 0 to 0.4 mass % of Si,
• and optionally at least one selected from the group consisting of 0.1 to 3.0 mass % of Mn, 0.1 to 3.0 mass % of Ni, 0.005 to 1.000 mass % of Cu, 0.01 to 1.00 mass % of Cr, and 0.01 to 1.00 mass % of Zr, 0.005 to 1.000 mass % of Zn, and a total content of Ti, B, and V of 0.005 to 0.500 mass %,
• with a balance of Al and unavoidable impurities, wherein a boundary length of a second phase particle having a longest diameter of 3 μm or more is 10 mm/mm2 or more in a metal structure.