JP2018053280A - NiTa-BASED ALLOY, TARGET MATERIAL AND MAGNETIC RECORDING MEDIA - Google Patents

Abstract

A sputtering target material in which a predetermined amount of Fe or Co is added to a NiTa alloy, a Ta compound phase is finely dispersed to prevent composition unevenness and mechanical strength is improved, and an adhesion layer is formed using the sputtering target material Provision of magnetic recording media. A Ni-Ta alloy containing 15 to 50 at% of Ta, the balance being Ni, Fe, Co and inevitable impurities, and the ratio of Ni, Fe and Co is at%, Ni: Fe: Co = 98.5 to 20: 0 to 50: 0 to 60, the total amount of Fe and Co is 1.5 at% or more, has an FCC phase and a Ta compound phase, and in the Ta compound phase An alloy for an adhesion layer of a magnetic recording medium, a sputtering target material and a magnetic recording medium having a maximum inscribed circle diameter of 10 μm or less. Further, at least one element selected from Al, Ga, In, Si, Ge, Sn, Zr, Hf, B, Cu, P, C, Ru, or Cr is added at 10 at. %. An alloy for an adhesion layer of a magnetic recording medium, which is preferably contained in an amount of at most%. [Selection] Figure 1

Description

  The present invention relates to an alloy for an adhesion layer of a Ni-Ta magnetic recording medium used as an adhesion layer in a perpendicular magnetic recording medium, a sputtering target material, and a magnetic recording medium.

  In recent years, the magnetic recording technology has been remarkably advanced, and the recording density of magnetic recording media has been increased to increase the capacity of the drive, realizing a higher recording density than the conventional in-plane magnetic recording media. A perpendicular magnetic recording system capable of being used has been put into practical use. The perpendicular magnetic recording system is a method suitable for high recording density, in which the easy magnetization axis is oriented in the perpendicular direction with respect to the medium surface in the magnetic film of the perpendicular magnetic recording medium.

For example, as described in Japanese Patent No. 4499044 (Patent Document 1), an adhesion layer, a soft magnetic layer, a seed layer, an intermediate layer, a magnetic recording layer, and a protective layer are formed on a substrate such as a glass substrate or an Al substrate. The soft magnetic layer has a Co alloy, the seed layer has a first seed layer on the soft magnetic layer side and a second seed layer on the intermediate layer side, and the first seed layer is Cr, Ta, Ti, An amorphous alloy containing one or more elements selected from Nb, Si, and Al. The second seed layer is one selected from Cr, Ta, Ti, Nb, V, W, Mo, and Cu as Ni. It is composed of a perpendicular magnetic recording medium made of a crystalline alloy containing the above elements.

Moreover, as a target used for the formation of the adhesion layer, JP2013-127111A
Ni-Ta sputtering target material as shown in Japanese Patent Publication (Patent Document 2) is used. The sputtering target material of Patent Document 2 improves the strength of the sputtering target material by containing a NiTa compound phase and a pure Ta phase in the sputtering target material, and reduces cracking and particle generation during sputtering.

Japanese Patent No. 4499044 JP 2013-127111 A

On the other hand, the sputtering target material of Patent Document 2 described above improves the strength of the sputtering target material by containing a pure Ta phase, and reduces cracking and particle generation during sputtering. However, due to the presence of pure Ta phase in the sputtering target material, there is a problem that a large composition change occurs in the microstructure of the sputtering target material and the composition change is reflected in the sputtered film reflecting the composition change. In recent years, there has been a demand for further improvement in the strength of the sputtering target for the adhesion layer, and there is a limit in improving the strength with the pure Ta phase.

In order to solve the above-mentioned problems, the inventors have intensively developed, and as a result, increased the strength of the sputtering target material without using pure Ta, preventing cracks and particles during sputtering, and uneven composition of the sputtered film. The sputtering target material which can prevent was discovered. Furthermore, according to the present invention, by adding a predetermined amount of Fe or Co to the NiTa alloy, the Ta compound phase can be finely dispersed, and the mechanical strength can be improved as compared with the prior art.

The gist of the invention is that
(1) It is made of a Ni-Ta alloy, Ta contains 15 to 50 at%, the balance is made of Ni, Fe, Co and unavoidable impurities, and the ratio of Ni, Fe and Co is at%, Ni: Fe: Co = 98.5 to 20: 0 to 50: 0 to 60, the total amount of Fe and Co is 1.5 at% or more, and has an FCC phase and a Ta compound phase, and a Ta compound phase An alloy for an adhesion layer of a magnetic recording medium, characterized in that the diameter of the maximum inscribed circle that can be drawn inside is 10 μm or less.

(2) In addition to the Ni—Ta alloy described in (1), Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, Ru, A total of 10 at. Or more elements selected from Cr. An alloy for an adhesion layer of a magnetic recording medium, characterized by comprising:
(3) A sputtering target material formed using the alloy for an adhesion layer of a magnetic recording medium according to (1) or (2).
(4) A magnetic recording medium using the adhesion layer alloy according to (1) or 2.

As described above, the present invention provides a sputtering target material in which a predetermined amount of Fe or Co is added to a NiTa alloy so that the Ta compound phase is finely dispersed, there is no composition unevenness, and mechanical strength is improved. An object of the present invention is to provide a magnetic recording medium in which an adhesion layer is formed using the same.

It is a figure which shows the result of having observed the microstructure concerning this invention with the scanning electron microscope (SEM).

As shown in FIG. 1, the gray portion corresponding to the reference numeral 1 is an FCC phase made of NiFe, and the white portion corresponding to the reference numeral 2 is formed by two phases of a Ta compound phase consisting of a Ni ₃ Ta phase and a Fe ₇ Ta ₃ phase. It can be seen that a microstructure is formed. The Ta compound phase is characterized by forming a fine phase having a maximum inscribed circle diameter of 10 μm or less. By having a microstructure in which the Ta compound phase is finely dispersed in this way, there is no composition unevenness of the sputtering target material, and the strength is improved.

Hereinafter, the reasons for limitation related to the present invention will be described.
In the Ni—Ta-based alloy according to the present invention, Ta contains 15 to 50 at%, and the balance consists of Ni, Fe, Co, and unavoidable impurities. When Ta is less than 15 at%, the amorphous property of the sputtered film required as the adhesion layer is lost, and the characteristics as the adhesion layer are deteriorated. On the other hand, if it exceeds the range of 50 at%, the amount of Ta compound increases, the diameter of the maximum inscribed circle that can be drawn in the Ta compound phase becomes 10 μm or more, and sufficient mechanical strength cannot be obtained.

  In the Ni—Ta alloy, the ratio of Ni, Fe, and Co is at%, and Ni: Fe: Co = 98.5 to 20: 0 to 50: 0 to 60. The reason why the amount of Ni is made 98.5 at% or less is that sufficient strength as an adhesion layer cannot be obtained when the total amount of Fe and Co is less than 1.5 at%. Moreover, if the amount of Ni is less than 20 at%, the amount of Ni having toughness is too small and the mechanical strength is lowered.

Furthermore, Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C
, Ru, Cr are hereinafter referred to as M elements, which are elements that refine crystal grains when added in a small amount. One or more of these Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, Ru, and Cr are limited to 0 to 10% in at% amount. . The reason is that when it exceeds 10%, the tissue is enlarged and the mechanical strength is lowered, and preferably 5% or less.

  In the present invention, it is desirable to solidify and form a fine gas-quenched atomized powder, and furthermore, a powder that is heat-treated in a vacuum or an inert atmosphere after removing coarse powder by classification is suitable. When the classified powder has a particle size distribution D50 of 230 μm or less, the desired fine structure can be achieved. On the other hand, when a powder having a D50 larger than 230 μm is used, the intended fine structure cannot be sufficiently achieved. Desirably, D50 is 200 μm or less.

  In addition, by heat-treating the classified powder in vacuum or in an inert gas at 300 to 800 ° C., the rapidly solidified state of the powder surface is released, and by solidifying and molding it, the desired fine structure can be obtained. Can be achieved. On the other hand, when the gas quench atomized powder is solidified without heat treatment, a coarse Ta compound may remain, and the target fine structure cannot be sufficiently achieved.

  About solidification shaping | molding of a powder, a fine structure | tissue is achieved by making a shaping | molding temperature into 1000-1200 degreeC and making a shaping | molding pressure into 100-150 MPa. However, if the molding temperature is less than 1000 ° C. and the molding pressure is less than 100 MPa, the desired fine structure cannot be sufficiently achieved. Conversely, when the molding temperature exceeds 1200 ° C. and the molding pressure exceeds 150 MPa, the structure is fine. The inscribed circle diameter of the Ta compound phase cannot be 10 μm or less. Therefore, the molding temperature was 1000 to 1200 ° C., and the molding pressure was 100 to 150 MPa.

  According to the above, a sputtering target material capable of preventing uneven composition of the sputtered film by making the constituent phase a fine structure in which the inscribed circle diameter of the Ta compound phase microstructure is 10 μm or less is made possible, and the sputtering target material This is an extremely effective technique for improving the quality of the magnetic recording medium by increasing the strength of the magnetic recording medium and preventing cracking during sputtering.

  Further, as the rapid solidification treatment method of the present invention, a gas atomizing method is preferred, in which a spherical powder with a small filling ratio and a high filling rate and suitable for sintering is obtained. As a powder pressure sintering method, methods such as hot pressing, hot isostatic pressing, energizing pressure sintering, hot extrusion, and the like can be applied. Among them, the hot isostatic press is particularly preferable because the pressurization pressure is high and a dense sintered body can be obtained even if the maximum temperature is kept low to suppress the coarsening of the intermetallic compound phase.

  In addition, as long as the target material of this invention can control a micro structure, both a melt casting method and a powder sintering method are applicable. In addition, in order to control the maximum inscribed circle diameter of the microstructure of the Ta compound phase to 10 μm or less in the microstructure, when applying the melt casting method, for example, cast the molten alloy into a mold cooled by water cooling or the like. Therefore, it is desirable to increase the solidification rate as compared with general casting.

Hereinafter, the present invention will be specifically described with reference to examples.
Ni—Fe—Co—Ta— (M) alloy powders were prepared from the respective component compositions shown in Tables 1 and 2 by gas atomization. The obtained powder is classified to 500 μm or less to remove coarse powder, the classified powder is subjected to vacuum heat treatment at 300 ° C., and the heat-treated powder is used as a raw material powder for HIP molding (hot hot pressure press) It was. A billet for HIP molding was prepared by filling a raw material powder into a carbon steel can having a diameter of 250 mm and a length of 50 mm, followed by vacuum degassing and sealing. This powder-filled billet was subjected to HIP molding at the molding temperature and molding pressure shown in Tables 1 and 2 under the condition of holding time of 5 hours. Thereafter, a sputtering target material having a diameter of 180 mm and a thickness of 7 mm was produced from the molded body.

As for the evaluation method, the micro of the sputtering target material is obtained by taking a scanning electron microscope (SEM) test piece from the end of the sputtering target, polishing the cross section of the test piece, taking a backscattered electron image, and drawing it in the compound. The tangent circle was evaluated.
The strength of the sputtering target material was evaluated by a three-point bending test in which a TP having a width of 4 mm, a length of 3 mm, and a length of 25 mm was determined with a wire. The three-point bending test was performed at a distance between fulcrums of 20 mm, and the stress (N) at that time was reduced in the longitudinal direction, and the three-point bending strength was determined based on the following formula.
Three-point bending strength (MPa) = [3 × stress (N) × distance between supporting points (mm)] / [2 × width of test piece (mm) × (thickness of test piece (mm)] 2.

As shown in Table 1 and Table 2, 1-32, 53-66 are examples of the present invention. 33-52 and 67-70 are comparative examples.

  Regarding the powders used in Tables 1 and 2, those having a particle size D50 of 200 μm or less were indicated as I, those exceeding 200 to 230 μm were indicated as II, and those exceeding 230 μm were indicated as III. In addition, the heat-treated material was indicated as I, and the non-heat-treated material as II.

  As shown in Table 2, Comparative Example No. Although 33 is composed of an FCC phase and a Ta compound, the Ta component composition is high, the maximum inscribed circle diameter of the microstructure of the Ta compound phase is increased to 13 μm, and the bending stress is low. Comparative Example No. Similarly, the component composition of Ta is high, the maximum inscribed circle diameter of the microstructure of the Ta compound phase is coarsened to 15 μm, and the bending stress is low. Comparative Example No. In 35 to 37, the maximum inscribed circle diameter of the microstructure of the Ta compound phase is 10 μm or less, but the component composition of Ni having toughness is low and the mechanical strength is lowered.

  Comparative Example No. In Nos. 38 to 40, the maximum inscribed circle diameter of the microstructure of the Ta compound phase is 10 μm or less, but since Fe or Co is not added, the mechanical strength is low. Comparative Example No. No. 41 has a low mechanical strength because the molding pressure is as low as 90 MPa. Comparative Example No. Nos. 42 to 45 were formed by HIP molding at a molding temperature of 1350 ° C., which is higher than that of the present invention. Therefore, the maximum inscribed circle diameter of the Ta compound phase microstructure is larger than 10 μm, and the mechanical strength is low. It has become.

  Comparative Example No. In Nos. 46 to 47, since the powder was not heat-treated, a coarse Ta compound remained and the mechanical strength was low. Comparative Example No. In Nos. 48 to 49, since powders having a powder particle size D50 of more than 200 to 230 μm were used, the maximum inscribed circle diameter of the microstructure of the Ta compound phase was slightly increased to 11 μm, and the bending stress was low. Comparative Example No. In Nos. 50 to 52, powders having a powder particle size D50 exceeding 230 μm were used, so that the maximum inscribed circle diameter of the microstructure of the Ta compound phase was coarsened, and the bending stress was low.

  No. 53-66 are examples of the present invention. 67 to 70 are comparative examples. Although both are composed of FCC phase and Ta compound phase, Comparative Example No. In Nos. 67 to 70, the element M exceeds 10%, the maximum inscribed circle diameter of the microstructure of the Ta compound phase is coarser than 10 μm, and the bending stress is low. On the other hand, No. which is an example of the present invention. Since 1-3, 53-66 satisfy | fills the conditions of this invention, all show that the bending stress of a sputtering target material is high.

  As described above, by adding a predetermined amount of Fe or Co to NiTa according to the present invention, the NiFe (Co) -Ta compound phase is finely dispersed, thereby increasing the strength of the sputtering target material, and at the time of sputtering. This has an extremely excellent effect of enabling a sputtering target material that can prevent cracks and particles and prevent uneven composition of the sputtered film.

1 FCC phase 2 Ta compound phase


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (4)

It is made of a Ni—Ta alloy, Ta contains 15 to 50 at%, the balance is made of Ni, Fe, Co and inevitable impurities, and the ratio of Ni, Fe and Co is at%, Ni: Fe: Co = 98.5 to 20: 0 to 50: 0 to 60, the total amount of Fe and Co is 1.5 at% or more, and has an FCC phase and a Ta compound phase, An alloy for an adhesion layer of a magnetic recording medium, wherein a diameter of a maximum inscribed circle that can be drawn is 10 μm or less. The Ni-Ta alloy according to claim 1 is further selected from Al, Ga, In, Si, Ge, Sn, Zr, Ti, Hf, B, Cu, P, C, Ru, and Cr as M elements. A total of 10 at. An alloy for an adhesion layer of a magnetic recording medium, characterized by comprising: A sputtering target material using the alloy for an adhesion layer of a magnetic recording medium according to any one of claims 1 and 2. A magnetic recording medium using the adhesion layer alloy according to claim 1.