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JP-7855386-B2 - FeCo alloy for soft magnetic layer of magnetic recording media

JP7855386B2JP 7855386 B2JP7855386 B2JP 7855386B2JP-7855386-B2

Inventors

  • 越智 亮介
  • 相川 芳和

Assignees

  • 山陽特殊製鋼株式会社

Dates

Publication Date
20260508
Application Date
20220330

Claims (3)

  1. It comprises one or more TCR elements selected from Ru and Re, and one or more TAM elements selected from Zr, V, Nb, Ta, Mo, and W, with the remainder being Fe, Co, and unavoidable impurities. The total content of the above TCR elements TCR (at%), the total content of the above TAM elements TAM (at%), and the content of Fe and Co (at%) all satisfy the following formulas (1)-(4): (1) 0.1 ≤ TCR ≤ 10.0 (2) 11.0 ≤ TAM ≤ 25.0 (3) 16.0≦[TCR/2+TAM]≦25.0 (4) 0.20≦[Fe/(Fe+Co)]≦0.80 It has a microstructure consisting of a (Fe,Co) phase mainly composed of Fe and/or Co, and an intermetallic compound phase containing the above TCR element or the above TAM element. In the above microstructure, the number of (Fe,Co) phases where the diameter of the smallest circumscribed circle surrounding the outside of the (Fe,Co) phase exceeds 30 μm is zero, an FeCo-based alloy for the soft magnetic layer of a magnetic recording medium.
  2. It comprises one or more TCR elements selected from Ru and Re, and one or more TAM elements selected from Zr, V, Nb, Ta, Mo, and W, with the remainder being Fe, Co, and unavoidable impurities. The total content of the above TCR elements TCR (at%), the total content of the above TAM elements TAM (at%), and the content of Fe and Co (at%) all satisfy the following formulas (1)-(4): (1) 0.1 ≤ TCR ≤ 10.0 (2) 11.0 ≤ TAM ≤ 25.0 (3) 16.0≦[TCR/2+TAM]≦25.0 (4) 0.20≦[Fe/(Fe+Co)]≦0.80 It has a microstructure consisting of a (Fe,Co) phase mainly composed of Fe and/or Co, and an intermetallic compound phase containing the above TCR element or the above TAM element. In the above microstructure, the number of (Fe,Co) phases whose minimum circumscribed circle diameter surrounding the outside of the (Fe,Co) phase exceeds 30 μm is zero. An FeCo alloy for the soft magnetic layer of a magnetic recording medium, wherein, in a randomly selected field of view of the above-described microstructure with an area of 3250 μm² , the maximum inscribed circle diameter that can be drawn inside the (Fe,Co) phase is 1.8 μm or more, and the minimum circumscribed circle diameter surrounding the outside of that phase is 30 μm or less, and there are 5 or more (Fe,Co) phases.
  3. A sputtering target material for the soft magnetic layer of a magnetic recording medium, wherein the material is the FeCo-based alloy described in claim 1 or 2.

Description

This invention relates to FeCo-based alloys. More specifically, this invention relates to FeCo-based alloys suitable for the soft magnetic layer of a magnetic recording medium. In recent years, with the increasing capacity of magnetic recording media, the practical application of media employing perpendicular magnetic recording (perpendicular magnetic recording media) has been progressing. In perpendicular magnetic recording media, the easy magnetization axis is oriented perpendicular to the media surface within the magnetic film. This perpendicular magnetic recording media is suitable for high recording densities. A perpendicular magnetic recording medium has a magnetic recording layer and a soft magnetic layer. Furthermore, the perpendicular magnetic recording medium has a seed layer, an undercoat layer, etc., between the magnetic recording layer and the soft magnetic layer. The soft magnetic layer prevents the spread of magnetic flux generated from the head during recording, ensuring a vertical magnetic field. From the perspective of increasing the recording density of magnetic recording media, there has been a demand for an amorphous soft magnetic layer with a high saturation magnetic flux density. FeCo alloys, for example, are known as materials for forming such soft magnetic layers. On the other hand, soft magnetic layers are also required to have high corrosion resistance depending on the application and operating environment of the magnetic recording medium. Japanese Patent Publication No. 2017-82330 (Patent Document 1) discloses an alloy for soft magnetic film layers that improves corrosion resistance without significantly reducing the saturation magnetic flux density. This alloy consists of one or more elements Ge, Ru, Rh, Pd, Re, Os, Ir, and Pt, one or more elements Sc, Y, lanthanides (atomic numbers 57-71), Ti, Zr, Hf, V, Nb, Ta, Mo, W, and B, with the remainder being Fe, Co, and unavoidable impurities, where the content of each element satisfies a predetermined relationship. Japanese Patent Publication No. 2017-82330 Figure 1 is an example of a scanning electron microscope image showing the microstructure of the FeCo alloy according to the present embodiment (No. 1).Figure 2 is an example of a scanning electron microscope image showing the microstructure of a FeCo-based alloy related to comparative example (No. 18).Figure 3 is an explanatory diagram illustrating the state of the (Fe,Co) phase in the microstructure shown in Figure 1. The present invention will be described in detail below, with reference to the drawings as appropriate, based on preferred embodiments. In this specification, the range "X to Y" means "X or greater and Y or less." [FeCo alloy] The FeCo alloy for the soft magnetic layer of a magnetic recording medium according to the present invention contains one or more TCR elements selected from Ru and Re, and one or more TAM elements selected from Zr, V, Nb, Ta, Mo, and W. The remainder is Fe, Co, and unavoidable impurities. This FeCo alloy has a component composition that satisfies the following formulas (1) to (4), and has a microstructure with an appropriate size and number of (Fe,Co) phases mainly composed of Fe and/or Co. The "(Fe,Co) phase mainly composed of Fe and/or Co" means a phase that is substantially formed from Fe or Co or both, with the content of other elements being negligible. [(1) 0.1 ≤ TCR ≤ 10.0] This FeCo alloy has a total content of 0.1 at% to 10.0 at% of one or more TCR elements selected from Ru and Re. From the viewpoint of improving the corrosion resistance of the soft magnetic layer obtained by sputtering, the total content of TCR elements TCR (at%) is preferably 0.5 at% or more, more preferably 1.0 at% or more, and even more preferably 2.0 at% or more. From the viewpoint of not excessively reducing the saturation magnetic flux density Bs, the total content of TCR (at%) is preferably 9.0 at% or less, more preferably 7.0 at% or less, and even more preferably 5.0 at% or less. [(2) 11.0 ≤ TAM ≤ 25.0] This FeCo alloy has a total content of one or more TAM elements selected from Zr, V, Nb, Ta, Mo, and W, which is 11.0 at% or more and 25.0 at% or less. From the viewpoint of increasing the amorphous nature of the FeCo alloy and contributing to the formation of intermetallic compounds with Fe and/or Co, the total content of TAM elements TAM (at%) is preferably 12.0 at% or more, more preferably 13.5 at% or more, and even more preferably 15.0 at% or more. From the viewpoint of not excessively reducing the saturation magnetic flux density Bs, the alloy content TAM (at%) is preferably 23.0 at% or less, more preferably 21.0 at% or less, and even more preferably 20.0 at% or less. [(3) 16.0≦[TCR/2+TAM]≦25.0] TCR and TAM elements are non-magnetic metallic elements, and both can contribute to a decrease in saturation magnetic flux density Bs. By controlling the value [TCR/2 + TAM], calculated from the total content of TCR elements (TCR) and the total content of TAM elem