CN-116547398-B - Aluminum alloy disk blank for magnetic disk and magnetic disk

Abstract

The invention relates to an aluminum alloy disc blank for a magnetic disc, which is characterized by being formed by an aluminum alloy, wherein the aluminum alloy contains 3.40-3.90 mass% of Mg, and the balance of Al and unavoidable impurities, and the conductivity of the aluminum alloy disc blank for the magnetic disc is more than 36.0% IACS.

Inventors

• KITAWAKI KOTARO
• Xiong Guhang
• Ban Benliao
• HIDEYUKI HATAKEYAMA

Assignees

• 株式会社UACJ
• 古河电气工业株式会社

Dates

Publication Date

20260505

Application Date

20211213

Priority Date

20201215

Claims (5)

1. 1. An aluminum alloy disk blank for a magnetic disk, characterized in that it is formed of an aluminum alloy containing 3.40 to 3.90 mass% of Mg, the balance being made of Al and unavoidable impurities, and the electrical conductivity of the aluminum alloy disk blank for a magnetic disk is 36.0% IACS or more.
2. 2. The aluminum alloy disk blank for magnetic disks according to claim 1, wherein the aluminum alloy contains 3.40 to 3.65 mass% of Mg.
3. 3. The aluminum alloy disk blank for magnetic disks according to claim 1, wherein the aluminum alloy contains 3.40 to 3.55 mass% of Mg.
4. 4. The aluminum alloy disk blank for magnetic disks according to any one of claims 1 to 3, wherein the aluminum alloy further contains 1 or 2 or more elements selected from the group consisting of 0.30 mass% or less of Cu, 0.60 mass% or less of Zn, 0.60 mass% or less of Fe, 0.60 mass% or less of Si, 0.20 mass% or less of Cr, 0.0020 mass% or less of Be, 0.10 mass% or less of Sr, 0.10 mass% or less of Na, and 0.10 mass% or less of P.
5. 5. A magnetic disk comprising the aluminum alloy substrate formed from the aluminum alloy disk blank according to any one of claims 1 to 4, wherein the surface of the aluminum alloy substrate has a Ni-P plating layer and a magnetic layer on the Ni-P plating layer.

Description

Aluminum alloy disk blank for magnetic disk and magnetic disk Technical Field The present invention relates to an aluminum alloy disk blank for a magnetic disk and a magnetic disk using the aluminum alloy disk blank for a magnetic disk. Background A hard disk drive (hereinafter, abbreviated as "HDD") is often used as a storage device in an electronic device such as a computer or a video recording device. The HDD has a disk for recording data incorporated therein. The magnetic disk includes an aluminum alloy substrate formed of an aluminum alloy and having a circular ring shape, a Ni-P plating layer covering the surface of the aluminum alloy substrate, and a magnetic layer laminated on the Ni-P plating layer. In recent years, the amount of information recorded in HDDs has been increasing for business applications such as servers and data centers, and for home applications such as personal computers and video recording devices. In order to cope with such a situation, the capacity of the HDD is increased, and it is demanded to increase the recording density of the magnetic disk mounted in the HDD. In order to improve the recording density of the magnetic disk, a smooth Ni-P plating treatment layer is formed on an aluminum alloy substrate. The magnetic disk is generally manufactured by the following method. First, a rolled sheet of aluminum alloy is punched into an annular shape to produce a disc blank (disc blank). Then, the disc blank is heated while being pressed from both sides in the thickness direction, thereby reducing warpage of the disc blank. Then, the disc blank is subjected to cutting and grinding, and formed into a desired shape, thereby obtaining an aluminum alloy substrate. The aluminum alloy substrate thus obtained can be subjected to pretreatment for forming a ni—p plating treatment layer, electroless ni—p plating treatment, and sputtering of a magnetic layer in this order, whereby a magnetic disk can be produced. As an aluminum alloy used for an aluminum alloy substrate, JIS a5086 alloy is often used. According to the demand of multimedia and the like, a disk is required to have a large capacity and a high density. In order to further increase the capacity, the amount of floating of the magnetic head during reading and writing tends to be reduced, however, if a convex defect exists on the surface of the magnetic disk, the magnetic head collides with the magnetic head, and recording errors are caused, so that it is required to reduce the convex defect. In addition, in order to enable stable processing and use, high yield strength has been conventionally required for aluminum alloy disc blanks. Accordingly, various studies have been made on a technique for reducing foreign matters such as intermetallic compounds existing in an aluminum alloy substrate in order to further improve smoothness by reducing convex defects. For example, patent document 1 describes a method for reducing Mg 2 Si compound and al—fe compound in an aluminum alloy sheet for a magnetic disk substrate containing 2.0 to 6.0 wt% Mg, 0.05 to 0.15 wt% Cu, 0.10 to 0.30 wt% Zn, 0.05 to 0.12 wt% Zr, 0.2 wt% or less (including 0 wt%) Sn, wherein the content of Cu, zn, zr, sn satisfies the relation of 0.15 wt% or less 2cu+6zr—3zn—0.1Sn or less than 0.32 wt% (Cu, zr, zn, sn in the formula is each wt%), 1 or 2 kinds of Cr of more than 0.01 wt% and less than 0.05 wt% Mn, and the balance being unavoidable impurity elements and Al. (Prior art literature) (Patent literature) Patent document 1 Japanese patent laid-open No. 10-008177 According to the method of patent document 1, the cooling rate at the time of solidification of the molten metal can be increased by twin roll continuous casting, and the intermetallic compound can be made fine. However, the method of patent document 1 has a problem that it is difficult to reduce the convex defect of the disc blank caused by factors other than the intermetallic compound. In addition, in the method of patent document 1, it is difficult to sufficiently improve the yield strength of the disc blank. Disclosure of Invention Problems to be solved by the invention The present invention has been made in view of the above-described problems, and the inventors have found that by controlling the Mg amount and the electrical conductivity of an aluminum alloy, an aluminum alloy disk blank for a magnetic disk can be obtained which has reduced convex defects, improved smoothness, and high yield strength, and thus have completed the present invention. . Means for solving the technical problems The invention provides an aluminum alloy disc blank for a magnetic disc, which is characterized by being formed by an aluminum alloy, wherein the aluminum alloy contains 3.40-3.90 mass% of Mg, and the balance of Al and unavoidable impurities, and the electrical conductivity of the aluminum alloy disc blank for the magnetic disc is more than 36.0% IACS. Another aspect of the present invention is an aluminum alloy disk blank