ALUMINUM ALLOY SHEET FOR MAGNETIC DISK, MANUFACTURING METHOD THEREFOR, MAGNETIC DISK SUBSTRATE AND MAGNETIC DISK

• Main Authors: HATAKEYAMA HIDEYUKI, YONEMITSU MAKOTO, KITAWAKI KOTARO, SAKAMOTO RYO, OTA YUKI
• Format: Patent
• Language: English; Japanese
• Published: 19.03.2020
• Subjects: ALLOYS; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; METALLURGY; PERFORMING OPERATIONS; POWDER METALLURGY; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

To provide an aluminum alloy sheet for a magnetic disk capable of enhancing smoothness of a Ni-P plating coated film while suppressing increase of manufacturing cost, a manufacturing method therefor, a magnetic disk substrate, and the magnetic disk.SOLUTION: An aluminum alloy sheet for a magnetic disk has a chemical component containing, V:0.0025 to 0.1000 mass%, Cu:0.005 to 0.150 mass%, Zn:0.05 to 0.60 mass% and the balance Al with inevitable impurities. The number of an Al-V-based inclusion having the longest diameter of 0.5 μm or more of the Al-V-based inclusion exposed to a surface is 1/6000 mmor less.SELECTED DRAWING: Figure 1 【課題】製造コストの増大を抑制しつつ、Ｎｉ−Ｐめっき皮膜の平滑性を高めることができる磁気ディスク用アルミニウム合金板、その製造方法、磁気ディスク基板及び磁気ディスクを提供する。【解決手段】磁気ディスク用アルミニウム合金板は、Ｖ：０．００２５〜０．１０００質量％、Ｃｕ：０．００５〜０．１５０質量％、Ｚｎ：０．０５〜０．６０質量％を含有し、残部がＡｌ及び不可避的不純物からなる化学成分を有している。表面に露出したＡｌ−Ｖ系介在物のうち、０．５μｍ以上の最長径を有するＡｌ−Ｖ系介在物の数が１個／６０００ｍｍ2以下である。【選択図】図１