US 12,087,342 B2
Aluminum alloy disc blank for magnetic disc and magnetic disc
Kotaro Kitawaki, Tokyo (JP); Ryo Sakamoto, Tokyo (JP); Wataru Kumagai, Tokyo (JP); Hideyuki Hatakeyama, Tokyo (JP); Ryohei Yamada, Tokyo (JP); Shinpei Todo, Tokyo (JP); and Toshihiro Nakamura, Tokyo (JP)
Assigned to UACJ CORPORATION, Tokyo (JP); and FURUKAWA ELECTRIC CO., LTD., Tokyo (JP)
Filed by UACJ CORPORATION, Tokyo (JP); and FURUKAWA ELECTRIC CO., LTD., Tokyo (JP)
Filed on Jun. 22, 2023, as Appl. No. 18/339,994.
Application 18/339,994 is a continuation of application No. PCT/JP2021/047225, filed on Dec. 21, 2021.
Claims priority of application No. 2020-215207 (JP), filed on Dec. 24, 2020.
Prior Publication US 2023/0335161 A1, Oct. 19, 2023
Int. Cl. G11B 5/73 (2006.01); G11B 5/84 (2006.01); G11B 5/858 (2006.01)
CPC G11B 5/73919 (2019.05) [G11B 5/8404 (2013.01); G11B 5/858 (2013.01)] 8 Claims
OG exemplary drawing
 
1. An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy comprising Fe: 0.005 to 1.800 mass %, Mn: 1.80 mass % or less, Cu: 1.00 mass % or less, Si: 14.00 mass % or less, Zn: 0.70 mass % or less, wherein Mn, Cu, Si, and Zn are present, with a balance being Al and inevitable impurities, and wherein the aluminum alloy disc blank for a magnetic disc has a flatness change 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 μm or less.