阅读说明：本技术 磁记录介质的籽晶层用合金 (Alloy for seed layer of magnetic recording medium ) 是由 井本未由纪 松原庆明 于 2020-06-15 设计创作，主要内容包括：本发明的课题在于,提供一种可以得到大容量且耐蚀性优异的磁记录介质的籽晶层用合金,为了解决上述课题,本发明提供一种磁记录介质的籽晶层用合金,其包含Ni、选自Fe和Co中的至少1种、选自W、Mo、Ta、Cr、V和Nb中的1种或2种以上的元素M1、选自Au、Ag、Pd、Rh、Ir、Ru、Re和Pt中的1种或2种以上的元素M2、和不可避免的杂质,元素M1的含有率为2～13at.％,元素M2的含有率为2～13at.％,元素M1的含有率与元素M2的含有率之和为4～15at.％,合金中的Ni、Fe和Co的含有率(at.％)之比Ni∶Fe∶Co设为X∶Y∶Z时,X为20～100,Y为0～50,Z为0～60。(The present invention addresses the problem of providing an alloy for a seed layer that can provide a large capacity and excellent corrosion resistance for a magnetic recording medium, and in order to solve the above-mentioned problems, the present invention provides an alloy for a seed layer for a magnetic recording medium, the alloy comprises Ni, at least 1 selected from Fe and Co, 1 or more than 2 selected from W, Mo, Ta, Cr, V and Nb, M1 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt, 1 or more than 2 selected from M2 and inevitable impurities, wherein the content of the element M1 is 2-13 at.%, the content of the element M2 is 2-13 at.%, the sum of the content of the element M1 and the content of the element M2 is 4-15 at.%, and when the ratio of the content (at.%) of Ni, Fe and Co in the alloy is set as X: Y: Z, X is 20-100, Y is 0-50 and Z is 0-60.)

1. An alloy for a seed layer of a magnetic recording medium, comprising: ni; at least 1 selected from Fe and Co; 1 or more than 2 elements M1 selected from W, Mo, Ta, Cr, V and Nb; 1 or more than 2 elements M2 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt; and the inevitable impurities, and the like, are contained,

the content of the element M1 is not less than 2 at.% and not more than 13 at.%,

the content of the element M2 is not less than 2 at.% and not more than 13 at.%,

the sum of the content of the element M1 and the content of the element M2 is 4 at.% or more and 15 at.% or less,

when the ratio of the Ni content at.%, the Fe content at.%, and the Co content at.% in the alloy is set as X: Y: Z, X is 20 to 100 inclusive, Y is 0 to 50 inclusive, and Z is 0 to 60 inclusive.

2. The alloy for a seed layer according to claim 1,

the alloy further contains 1 or 2 or more elements M3 selected from Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C and Mn,

the content of the element M3 is more than 0 at.% and not more than 5 at.%.

3. A sputtering target formed from the alloy of any one of claims 1 or 2.

4. A magnetic recording medium having a seed layer formed of the alloy of any one of claims 1 or 2.

Technical Field

The present invention relates to an alloy for a seed layer of a magnetic recording medium. More specifically, the present invention relates to a Ni-based alloy suitable for formation of a seed layer.

Background

In order to increase the capacity of recording devices, recording media using a perpendicular magnetic recording method have been developed. In the perpendicular recording system, in a magnetic film of a recording medium, the axis of easy magnetization is oriented in a perpendicular direction with respect to the medium surface. The perpendicular magnetic recording medium employing this method has a high recording density.

The perpendicular magnetic recording medium has a magnetic recording layer and a soft magnetic layer. An intermediate layer such as a seed layer or a base film layer is formed between the magnetic recording layer and the soft magnetic layer. In a perpendicular magnetic recording medium, a high recording density can be obtained by making the crystal grains of the magnetic recording layer finer. The refinement of the crystal grains and the crystal orientation of the seed layer contribute to the refinement of the magnetic recording layer.

Japanese patent laid-open publication No. 2009-155722 discloses a target for an intermediate layer made of a Ni-W alloy. In this target, the strength ratio of the Ni solid solution, which is an fcc phase in X-ray diffraction, is controlled, thereby suppressing variation in the alloy film obtained by sputtering.

Japanese patent laid-open No. 2012 and 128933 discloses a seed layer target made of Ni-Fe-Co-M alloy. The alloy contains W, Mo, Ta, Cr, V or Nb as the element M. This target contributes to the refinement of crystal grains in the seed layer and the orientation toward the (111) plane.

Japanese patent application laid-open No. 2017-191625 discloses a target for a seed layer made of a Ni-Fe-Co-M alloy. The alloy contains Au, Ag, Pd, Rh, Ir, Ru, Re or Pt as the element M. This target contributes to the refinement of crystal grains in the seed layer and the orientation toward the (111) plane.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2009-155722

Patent document 2: japanese patent laid-open No. 2012 and 128933

Patent document 3: japanese patent laid-open publication No. 2017-191625

Disclosure of Invention

In recent years, further improvement in recording density has been demanded for magnetic recording media. There is still room for improvement in the orientation of the seed layer to the (111) plane and in the refinement of the crystal grains, which are obtained by using the targets made of alloys as disclosed in patent documents 1 to 3. Further, the present inventors have found that the seed layer obtained by using the target proposed in patent document 3 has low corrosion resistance, and therefore has a problem of corrosion under the use environment of the recording medium.

The invention aims to provide an alloy for a seed layer, which can obtain a magnetic recording medium with high recording density and excellent corrosion resistance.

Means for solving the problems

The alloy for a seed layer of a magnetic recording medium according to the present invention contains Ni, at least 1 selected from Fe and Co, 1 or 2 or more elements M1 selected from W, Mo, Ta, Cr, V and Nb, 1 or 2 or more elements M2 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt, and unavoidable impurities. The content of the element M1 in the alloy for a seed layer according to the present invention is 2 at.% or more and 13 at.% or less. The content of the element M2 in the alloy for a seed layer according to the present invention is 2 at.% or more and 13 at.% or less. The sum of the content of the element M1 and the content of the element M2 in the alloy for a seed layer according to the present invention is 4 at.% or more and 15 at.% or less. When the ratio of the content (at.%) of Ni, the content (at.%) of Fe, and the content (at.%) of Co in the alloy for a seed layer according to the present invention is defined as X: Y: Z, X is 20 or more and 100 or less, Y is 0 or more and 50 or less, and Z is 0 or more and 60 or less.

Preferably, the alloy for a seed layer according to the present invention further contains 1 or 2 or more elements M3 selected from Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C and Mn. The content of the element M3 in the alloy for a seed layer according to the present invention is more than 0 at.% and not more than 5 at.%.

From another viewpoint, the sputtering target according to the present invention is formed of the alloy for a seed layer according to the present invention. The sputtering target according to the present invention can obtain the alloy for a seed layer according to the present invention as a material.

From another viewpoint, the magnetic recording medium according to the present invention has a seed layer formed of the alloy for a seed layer according to the present invention. The seed layer may be obtained by sputtering. In this sputtering, a target made of the alloy for a seed layer according to the present invention can be used.

Effects of the invention

The alloy for a seed layer according to the present invention can provide a seed layer having high orientation to the (111) plane, fine grain size, and excellent corrosion resistance. The alloy for a seed layer according to the present invention contributes to the improvement of recording density and the suppression of corrosion of a magnetic recording medium.

Detailed Description

The present invention will be described in detail below based on preferred embodiments. In the present specification, "X to Y" indicating a range means "X or more and Y or less". In addition, "ppm" means "mass ppm" unless otherwise noted.

The alloy for a seed layer of a magnetic recording medium according to the present invention contains Ni, at least 1 selected from Fe and Co, 1 or 2 or more elements M1 selected from W, Mo, Ta, Cr, V and Nb, 1 or 2 or more elements M2 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt, and unavoidable impurities.

The Ni-Fe-Co alloy, which is composed of Ni, at least 1 selected from Fe and Co, and unavoidable impurities, has an fcc structure. Although the mechanism is not clear, both the element M1 and the element M2 have the function of changing the preferential orientation of the fcc structure of the Ni-Fe-Co based alloy from (200) to (111) and refining the crystal grains. The seed layer alloy according to the present invention is characterized by containing both the element M1 and the element M2 in the Ni — Fe — Co alloy. In the seed layer obtained from this alloy, the orientation of the element M1 to the (111) plane is significantly improved by the synergistic effect of the element M2, and the crystal grains are refined. As a result of intensive studies, the present inventors have found that the problem of low corrosion resistance of the seed layer, which has not been paid attention to in the past, is solved by the combination of the element M1 and the element M2. The perpendicular magnetic recording medium containing the seed layer can realize high recording density and avoid corrosion in use environment.

The content of the element M1 is 2 at.% or more from the viewpoint of improving the orientation to the (111) plane and the refinement of crystal grains. The excess element M1 transformed the seed layer to a structure other than the fcc structure. The content of the element M1 is 13 at.% or less, preferably 10 at.% or less, from the viewpoint that the seed layer can maintain the fcc structure.

As described above, the element M1 is 1 or 2 or more selected from W, Mo, Ta, Cr, V and Nb. When 2 or more elements M1 are selected, the content is adjusted as a total amount of the selected 2 or more elements.

The content of the element M2 is 2 at.% or more from the viewpoint of improving the orientation to the (111) plane and the refinement of crystal grains. The content of the element M2 is 13 at.% or less, preferably 10 at.% or less, from the viewpoint that the seed layer can maintain the fcc structure and from the viewpoint that the corrosion resistance is improved.

As described above, the element M2 is 1 or 2 or more selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt. When 2 or more elements M2 are selected, the content is adjusted as a total amount of the selected 2 or more elements.

From the viewpoint of increasing the recording density of the perpendicular magnetic recording medium and improving the corrosion resistance, the sum of the content of the element M1 and the content of the element M2 is 4 at.% or more, preferably 5 at.% or more. From the viewpoint that the seed layer can maintain the fcc structure, the sum of the content of the element M1 and the content of the element M2 is 15 at% or less, preferably 13 at% or less.

In the alloy for a seed layer according to the present invention, the ratio of the content of Ni (at.%), the content of Fe (at.%) and the content of Co (at.%), Ni, Fe, and Co, is represented by X, Y, and Z. Here, X + Y + X is 100.

In the alloy for a seed layer according to the present invention, X is 20 or more and 100 or less. By using an alloy in which X is 20 or more, a seed layer in which coercive force is suppressed can be obtained. From this viewpoint, X is preferably 40 or more, and more preferably 60 or more.

In the alloy for a seed layer according to the present invention, Y is 0 or more and 50 or less. By using an alloy in which Y is in this range, a seed layer in which coercive force is suppressed can be obtained. From this viewpoint, Y is preferably 2 or more, and more preferably 10 or more and 40 or less.

In the alloy for a seed layer according to the present invention, Z is 0 or more and 60 or less. By using an alloy having Z in this range, a seed layer in which the coercive force in the (111) direction is suppressed can be obtained. From this viewpoint, Z is preferably 40 or less, and more preferably 30 or less.

The alloy for a seed layer according to the present invention may contain 1 or 2 or more elements M3 selected from Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, and Mn. The element M3 promotes the grain refinement of the obtained seed layer. By using the seed layer obtained from the alloy containing the element M3, a further high recording density of the perpendicular magnetic recording medium is achieved.

The content of the element M3 is preferably more than 0 at.% and not more than 5 at.% from the viewpoint of grain refinement and the ability of the seed layer to maintain the fcc structure. More preferably, the content of the element M3 is 3 at.% or less. When 2 or more elements M3 are selected, the content is adjusted as a total amount of the selected 2 or more elements.

The sputtering target according to the present invention is formed of the alloy for a seed layer according to the present invention. In other words, the material of the sputtering target according to the present invention is an alloy containing Ni, at least 1 selected from Fe and Co, 1 or 2 or more elements M1 selected from W, Mo, Ta, Cr, V and Nb, 1 or 2 or more elements M2 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt, and inevitable impurities. The content of the element M1 in the sputtering target according to the present invention is 2 at.% or more and 13 at.% or less. The content of the element M2 in the sputtering target according to the present invention is 2 at.% or more and 13 at.% or less. The sum of the content of the element M1 and the content of the element M2 in the sputtering target according to the present invention is 4 at.% or more and 15 at.% or less. When the ratio of the content (at.%) of Ni, the content (at.%) of Fe, and the content (at.%) of Co, Ni, Fe, and Co, is X, Y, and Z, X is 20 to 100, Y is 0 to 50, and Z is 0 to 60. The sputtering target according to the present invention can be produced by: the raw material powder made of the seed layer alloy according to the present invention is heated under high pressure and solidified to form a sintered body, and the sintered body is processed into an appropriate shape by using a machine or the like.

The method and conditions for solidifying and molding the raw material powder composed of the seed layer alloy are not particularly limited as long as the effects of the present invention can be obtained, and the hot isostatic pressing method (HIP method), the hot pressing method, the spark plasma sintering method (SPS method), the hot extrusion method, and the like are appropriately selected.

For example, a raw material powder made of an alloy for a seed layer is first filled in a carbon steel can by a hot isostatic pressing method (HIP method). The can was vacuum degassed and sealed to form a billet. The sintered body is formed by subjecting the blank to HIP forming (hot isostatic pressing). The pressure for HIP molding is preferably 50MPa or more and 300MPa or less, and the sintering temperature is preferably 800 ℃ or more and 1350 ℃ or less. The obtained sintered body is wire-cut, lathed, and plane-polished to a predetermined shape, whereby a sputtering target can be obtained.

The raw material powder used for manufacturing the sputtering target is manufactured by a known atomization method. The type of the atomization method is not particularly limited, and may be an air atomization method, a liquid atomization method, or a centrifugal force atomization method. Preferably by gas atomization. In the atomization method, a known atomization apparatus and production conditions are appropriately selected and used.

The powder obtained by the atomization method is classified as necessary. By the classification, for example, particles (coarse powder) having a particle diameter of 500 μm or more, which inhibit sintering, can be removed. The classified powder can be used as a raw material powder for target production.

The seed layer according to the present invention is formed of the seed layer alloy according to the present invention. By sputtering using a target made of the alloy for a seed layer according to the present invention, a seed layer having the same composition as the alloy for a seed layer according to the present invention can be formed. In other words, the seed layer according to the present invention can be obtained by sputtering using a target of an alloy containing Ni, at least 1 selected from Fe and Co, 1 or 2 or more elements M1 selected from W, Mo, Ta, Cr, V and Nb, 1 or 2 or more elements M2 selected from Au, Ag, Pd, Rh, Ir, Ru, Re and Pt, and inevitable impurities as a material. The content of the element M1 in the alloy used as the target is 2 at.% or more and 13 at.% or less. The content of the element M2 in the alloy used as the target is 2 at.% or more and 13 at.% or less. The sum of the content of the element M1 and the content of the element M2 in the alloy used as the target is 4 at.% or more and 15 at.% or less. The ratio of the content of Ni (at.%), the content of Fe (at.%), and the content of Co (at.%) in the alloy used as the target, Ni: fe: setting Co as X: Y: and Z is 20 to 100, Y is 0 to 50, and Z is 0 to 60. The magnetic recording medium of the present invention has the seed layer of the present invention. The magnetic recording medium according to the present invention can be obtained by using the seed layer according to the present invention as a seed layer in a magnetic recording medium. The magnetic recording medium according to the present invention is preferably a perpendicular magnetic recording medium. The magnetic recording medium according to the present invention has a high recording density. The magnetic recording medium according to the present invention is excellent in corrosion resistance.

Examples

The effects of the present invention will be clarified by the following examples, but the present invention should not be construed as being limited to the descriptions of the examples.

The seed layer of the magnetic recording medium is formed on a glass substrate by sputtering using a target having the same composition as that of the seed layer. The seed layer is obtained by rapid cooling and solidification. The formation of the seed layer requires enormous labor. Therefore, the quenched ribbon produced by the single-roll quenching apparatus was evaluated in each evaluation test described later instead of the seed layer. In the single-roll type quenching apparatus, a quenched ribbon is produced through a step of quenching and solidifying in the same manner as sputtering. By using a quenched ribbon as a test piece, various characteristics of the seed layer obtained by sputtering can be easily evaluated.

30g of raw materials weighed so as to have the compositions shown in tables 1 to 3 below were charged into a water-cooled copper mold (diameter: 10mm, length: 40 mm). The mold was depressurized, and arc-melted in an argon atmosphere to obtain a molten base material. The molten base material was put into a quartz tube having a diameter of 15mm, and the melt was discharged from a nozzle and supplied to a single-roll quenching apparatus to produce a quenched ribbon. The conditions for producing the quenched ribbon were as follows. The obtained quenched ribbon was used as a test piece for each evaluation test.

Diameter of the nozzle for discharging the melt: 1mm

Atmospheric pressure: 61kPa

Spray differential pressure: 69kPa

The material of the roller: copper (Cu)

Diameter of the roll: 300mm

Rotation speed of the roller: 3000rpm

Gap between roller and nozzle for molten metal outflow: 0.3mm

In the composition shown in tables 1 to 3, for example, "2 Ta" and "3 Pt" of No.1 indicate that the content of Ta is 2 at.%, the content of Pt is 3 at.%, and the ratio X: Y: Z of the content (at.%) of Ni, Fe, and Co is 100: 0, respectively. The balance of the alloys shown in tables 1 to 3 is inevitable impurities.

[ coercive force ]

On a sample stage of a vibration sample type coercivity meter, a test piece was attached with a double-sided tape, and the coercivity was measured under the condition that a magnetic field of 144kA/m was initially applied. The rating is based on the criteria described below. The results are shown in tables 1 to 3 below. The evaluation was high in the order of III, II, I.

I: coercive force of 300A/m or less

II: a coercive force of more than 300A/m and not more than 500A/m

III: coercive force exceeding 500A/m

[ saturation magnetic flux ]

A test piece (about 15mg) was extracted from the quenched ribbon, and the saturation magnetic flux was measured under the condition of applying a magnetic field of 1200kA/m using a VSM apparatus (vibration sample type magnetometer). The rating is based on the criteria described below. The results are shown in tables 1 to 3 below. The evaluation was high in the order of III and I.

I: above 0.2T

III: less than 0.2T

[ grain diameter ]

A microstructure image of a cross section of the test piece in the roll direction was obtained. The crystal grain size was measured according to the specification of "microscopic test method for steel/crystal grain size" of JIS G0551 ". The rating is based on the criteria described below. The results are shown in tables 1 to 3 below. The evaluation was high in the order of III, II, I.

I: P/Lt is 1.5 or more

II: P/Lt is 1.2 or more and less than 1.5

III: P/Lt is less than 1.2

[ orientation ]

The test piece was attached to a glass plate with a double-sided tape so that the contact surface with the copper roll became the measurement surface, and a diffraction pattern was obtained by an X-ray diffraction apparatus. The diffraction conditions were as follows.

An X-ray source: cu-alpha rays

Scanning speed: 4 °/min

By this diffraction pattern, the intensity ratio I (111)/I (200) of the intensity I (111) of the X-ray diffracted at the (111) plane to the intensity I (200) of the X-ray diffracted at the (200) plane was obtained. The rating is based on the criteria described below.

I: the intensity ratio I (111)/I (200) is 0.7 or more

III: the intensity ratio I (111)/I (200) is less than 0.7

The test piece was also evaluated as III when the fcc structure was not retained and when the test piece was amorphized. The results are shown in tables 1 to 3 below. The evaluation was high in the order of III and I.

[ Corrosion resistance ]

A test piece (50mg) was extracted from the quenched ribbon, and the mass thereof was correctly weighed. The test piece was immersed in HNO having a concentration of 3 wt.%₃In 10ml of aqueous solution. After standing at room temperature for 1 hour, HNO in the immersion liquid was measured by ICP₃The amount of Ni, Fe and Co dissolved out in the aqueous solution. The total amount of elution of Ni, Fe and Co (Ni + Fe + Co) was determined and rated based on the following criteria. The results are shown in tables 1 to 3 below. Review ofValency is high in the order of III, II, I.

I: (Ni + Fe + Co) less than 50ppm

II: (Ni + Fe + Co) is 50ppm or more and less than 150ppm

III: (Ni + Fe + Co) is 150ppm or more

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

As shown in tables 1 to 3, in examples (nos. 1 to 39), in the alloy in which Ni, Fe, and Co satisfy the predetermined ratio, the content of the element M1 was adjusted to be 2 at.% or more and 13 at.% or less, the content of the element M2 was adjusted to be 2 at.% or more and 13 at.% or less, and the sum of the contents of the element M1 and the element M2 was adjusted to be 4 at.% or more and 15 at.% or less, and good evaluation results were obtained in terms of coercive force, saturation magnetic flux density, crystal grain diameter, orientation, and corrosion resistance. Further, in examples (Nos. 20 to 39), the crystal grain diameter was significantly increased by containing 5 at% or less of the element M3.

On the other hand, in comparative examples (nos. 40, 41 and 45), since the sum of the contents of the elements M1 and M2 was less than 4 at%, the crystal grains were not sufficiently refined, and the corrosion resistance was poor. In comparative example (No.48), the sum of the contents of elements M1 and M2 was 4 at.%, but element M2 was less than 2 at.%, and therefore, the corrosion resistance was poor and the orientation to the (111) plane was not improved. In the comparative examples (nos. 42 to 44, 46, 47 and 49), since the sum of the contents of the elements M1 and M2 exceeded 15 at%, the orientation toward the (111) plane was degraded, and the fcc structure could not be maintained. Further, a decrease in magnetic characteristics (saturation magnetic flux density) was also observed.

As described above, the seed layer alloy according to the present invention can provide a seed layer having excellent various characteristics. By applying this seed layer, a magnetic recording medium with high recording density can be obtained. From the evaluation results, the superiority of the present invention is evident.

Industrial applicability

The alloy for a seed layer and the target formed of the alloy described above can be applied to various magnetic recording media.