FeCoNbW alloy target material and hot-pressing preparation method thereof

Abstract

The invention discloses a FeCoNbW alloy target material and a hot-pressing preparation method thereof, and belongs to the technical field of magnetic storage target material manufacturing. The method comprises the following steps: carrying out vacuum melting on Fe blocks, Co blocks and Nb blocks, and then carrying out gas atomization to obtain FeCoNb alloy powder; the FeCoNbW alloy target material is obtained by mixing the FeCoNbW alloy powder and W powder, and then sequentially carrying out sheathing, die filling, degassing, hot pressed sintering and machining on the FeCoNbW alloy powder and the W powder. The W powder is added into the FeCoNb alloy powder to be combined into mixed powder of target components, the FeCoNb alloy powder forms metal alloy due to the components, demagnetization can be achieved, and the final magnetic permeability of the target material is improved. And then target blank sintering is conducted in a vacuum hot pressing sintering mode, the problems that components are not uniform, the target blank cracks during conventional plastic deformation and the magnetic permeability is low are solved, and the yield of the FeCoNbW alloy target is effectively increased.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic storage target material manufacturing, and in particular relates to a FeCoNbW alloy target material and a hot pressing preparation method thereof. Background Art

[0002] Fe-Co alloy is a soft magnetic material with excellent performance, with extremely high saturation flux density Bs (2.4T) and Curie temperature (980-1100℃), so it is suitable for making aviation electrical appliances (micro motors, electromagnets, relays, etc.) that require light weight, small size and high operating temperature. In addition, it has a large saturation magnetostriction coefficient λs, which can be used to make magnetostrictive transducers and various magnetic recording equipment, such as new sensors, magnetic recording read heads, filters, etc. Doping a small amount of Nb into Fe-Co alloy can react with impurities in the alloy to improve the soft magnetic properties of the alloy. On the other hand, it forms a Co-Nb local disordered area with Co and refines the size of the grains.

[0003] In order to further improve the magnetic properties of FeCoNb alloys, by introducing tungsten (W) into the alloy system, the hardness and wear resistance of the soft magnetic alloy material can be improved while maintaining good magnetic properties. There are generally two conventional methods for preparing target materials. One is to prepare by forging, rolling and heat treatment after smelting and casting. This method is suitable for metals or alloys with good plastic deformation ability; the other is to prepare by powder metallurgy. This method is suitable for difficult-to-deform metals or high-temperature alloys. For FeCoNbW alloys, due to the addition of W with extremely high melting point and extremely high hardness, although the hardness of the alloy is increased, the plastic deformation ability of the alloy is reduced. Therefore, it is difficult to prepare FeCoNbW alloy targets by smelting processing and plastic deformation. In addition, the prior art has not disclosed a method for preparing FeCoNbW alloy targets. Summary of the invention

[0004] The purpose of the present invention is to provide a hot pressing preparation method of a FeCoNbW alloy target material to solve the problem of low success rate of the FeCoNbW alloy target material; and a FeCoNbW alloy target material prepared by the hot pressing method.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In a first aspect, a hot pressing method for preparing a FeCoNbW alloy target comprises the following steps:

[0007] Step 1, vacuum melting Fe blocks, Co blocks, and Nb blocks and then atomizing them to obtain FeCoNb alloy powder;

[0008] Step 2, mixing FeCoNb alloy powder and W powder to obtain FeCoNbW alloy powder, and subjecting the powder to mold filling, vacuuming, hot pressing sintering, and machining in sequence to obtain FeCoNbW alloy target;

[0009] The specific sintering process of hot pressing sintering is as follows:

[0010] Under vacuum conditions, the temperature is increased from room temperature (25-30°C) to 950-1050°C at a first heating rate, and kept warm for 50-70 minutes to uniformly heat the internal mixed powder temperature; then the temperature is increased to 1100-1200°C at a second heating rate, and kept warm for 50-70 minutes; then the temperature is increased to 1300-1400°C at a third heating rate, and the pressure is increased during the heating process. When the temperature is reached, the pressure is increased to 35MPa, and the hot pressing sintering temperature is 1300-1400°C and the sintering pressure is 35MPa. The calcination is kept warm and pressure-maintained for 90-120 minutes; after sintering, the temperature and pressure are reduced to ≤200°C along with the furnace.

[0011] Furthermore, the mass percentage of elements in the FeCoNbW alloy target is Fe: 10-20at%, Nb: 4-6at%, W: 10-20at%, and the balance is Co.

[0012] Furthermore, the atomization pressure of the gas atomization is 3.6 MPa, the atomization temperature is 1650° C., and the atomization gas is argon.

[0013] Furthermore, the oxygen content of the FeCoNb alloy powder is ≤500ppm and the particle size is -200 mesh.

[0014] Furthermore, the purity of W powder is ≥3N5, and the particle size is -325 mesh.

[0015] Furthermore, the powder is mixed using a V-type powder mixer, which is filled with argon gas to protect against air entry, and the powder mixing time is 20-30 hours.

[0016] Furthermore, the mold used for molding is a graphite mold, the flatness of the mold is less than 1 mm, and a tungsten foil is placed between the FeCoNbW alloy powder and the mold to prevent Fe and C from reacting.

[0017] Furthermore, after the powder is loaded into the mold, it is placed in a vacuum hot pressing sintering furnace, the vacuum is evacuated to less than 100 Pa, and hot pressing sintering is started.

[0018] Furthermore, the first heating rate is 9-11°C / min, the second heating rate is 4-6°C / min, and the third heating rate is 3-4°C / min.

[0019] Furthermore, the machining uses a CNC grinder to process the thickness, and the wire cutting is used to cut the shape to the finished size, and then it is cleaned, dried and packaged.

[0020] Furthermore, the prepared FeCoNbW alloy target material is also subjected to post-processing operations including welding, surface treatment, inspection, cleaning, drying, packaging, etc. before shipment.

[0021] In a second aspect, a FeCoNbW alloy target is prepared by the above-mentioned hot pressing preparation method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention provides a hot pressing preparation method for a FeCoNbW alloy target material. This method uses FeCoNb alloy powder and W powder to form a mixed powder of the target component. Since the components of the FeCoNb alloy powder form a metal alloy, the magnetism can be demagnetized, thereby improving the final magnetic permeability of the target material. Then, the target blank is sintered by hot pressing. Through an optimized sintering process, the problems of uneven components, cracking of the target blank during conventional plastic deformation, and low magnetic permeability are solved, thereby effectively improving the yield rate of the FeCoNbW alloy target material. The temperature and pressure are precisely controlled by vacuum hot pressing sintering to achieve the regulation of the microstructure of the alloy target material, which is conducive to shrinkage and improvement of the organizational structure of the alloy, avoids oxidation of the material and contamination by impurities, and reduces energy consumption and production costs.

[0024] 2. The alloy target material obtained by the preparation method of the present invention has a purity of ≥3N5 (99.95%) and a density of ≥99%. It is composed of the following elements in atomic percentage: Fe: 10-20at%; W: 10-20at%; Nb: 4-6at%, and the balance is Co. The composition is precisely controlled by ±0.2at%, and the deviation is less than 0.5% at each location. The grains are uniform and fine (<50um), there are no internal defects, and the surface is smooth. According to the ASTM F2086-01 standard, the magnetic permeability is ≥30%. It has the advantages of precise composition control of the finished product, uniform composition distribution, no segregation, no inclusions, fine and uniform grains, high purity of the finished product, high density, high and uniform magnetic permeability, etc., and meets the use requirements. The target material is suitable for magnetron sputtering and has good soft magnetic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] Figure 1 It is a schematic diagram of the process flow of hot pressing preparation of a FeCoNbW alloy target material of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] See also Figure 1 A hot pressing method for preparing a FeCoNbW alloy target comprises the following steps:

[0030] Step 1, weigh Fe block, Co block, Nb block and W powder according to the element mass percentage of Fe: 15at%, Co: 65at%, Nb: 5at%, W: 15at%;

[0031] Fe blocks with a purity of ≥99.95%, Co blocks with a purity of ≥99.95%, and Nb blocks with a purity of ≥99.95% are added into a smelting furnace, and the molten metal obtained by vacuum smelting is atomized under high-pressure argon atomization conditions of a temperature of 1650° C. and a pressure of 3.6 MPa to obtain FeCoNb alloy powder with a particle size of -200 mesh and an oxygen content of 450±10ppm;

[0032] Step 2, adding the FeCoNb alloy powder and W powder with a purity of ≥99.95% and a particle size of -325 mesh into a V-type powder mixer, filling with argon gas to prevent air from entering, mixing the powder for 28 hours, and taking out the FeCoNbW alloy powder after the powder mixing is completed;

[0033] Select a suitable mold according to the size of the finished product. The mold material is graphite (CC). Lay tungsten foil on the inner wall of the mold. Put the FeCoNbW alloy powder into the package and compact it to ensure that the flatness of the mold is less than 1mm. After laying tungsten foil on the top of the powder, put in the pressure head, put the mold filled with powder into the vacuum hot pressing sintering furnace, evacuate to less than 100Pa, and start hot pressing sintering:

[0034] Under vacuum conditions, the temperature was raised from room temperature to 1000°C at a rate of 10°C / min, and kept at that temperature for 60 minutes, so that the temperature of the internal mixed powder was evenly heated; then the temperature was raised to 1150°C at a rate of 5°C / min, and kept at that temperature for 60 minutes; then the temperature was raised to 1380°C at a rate of 3.5°C / min, and the pressure was increased during the heating process. When the temperature was reached, the pressure was increased to 35MPa, and the hot pressing sintering temperature was 1380°C and the sintering pressure was 35MPa. The target was calcined at that temperature and pressure for 110 minutes; after the sintering was completed, the temperature and pressure were lowered to ≤200°C with the furnace, and a FeCoNbW alloy target blank with a flatness of <1mm was obtained;

[0035] Due to the extremely high hardness of FeCoNbW alloy, CNC grinder is used to process the thickness, and wire cutting is used to cut the shape to the finished size. After that, it is cleaned, dried and packaged to form the final FeCoNbW alloy target.

[0036] Example 2

[0037] A hot pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the element mass percentages of Fe: 10at%, Co: 65at%, Nb: 5at%, and W: 20at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0038] Example 3

[0039] A hot pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the element mass percentages of Fe: 20at%, Co: 65at%, Nb: 5at%, and W: 10at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0040] Example 4

[0041] A hot pressing preparation method for a FeCoNbW alloy target, which differs from Example 1 in that Fe blocks, Co blocks, and Nb blocks are weighed according to the element mass percentages of Fe: 20at%, Co: 55at%, Nb: 5at%, and W: 20at% to prepare FeCoNb alloy powder, which is then mixed with W powder; the remaining steps and parameters remain the same.

[0042] Example 5

[0043] A hot pressing preparation method of a FeCoNbW alloy target material is different from that of Example 1 in that the sintering temperature is replaced with 1300° C., and the other steps and parameters remain the same.

[0044] Comparative Example 1

[0045] A hot pressing preparation method of a FeCoNbW alloy target material is different from that of Example 1 in that the sintering temperature is replaced with 1250° C., and the other steps and parameters remain the same.

[0046] Comparative Example 2

[0047] A hot pressing preparation method of a FeCoNbW alloy target material is different from Example 1 in that the sintering temperature is replaced with 1450° C., and the other steps and parameters remain the same.

[0048] Comparative Example 3

[0049] A hot pressing preparation method of a FeCoNbW alloy target, which is different from that of Example 1 in that a direct powder mixing method is used, i.e., Fe powder, Co powder, Nb powder and W powder are weighed according to the element mass percentages of Fe: 15at%, Co: 65at%, Nb: 5at%, and W: 15at%; four kinds of metal powders are added into a V-type powder mixer, argon gas is filled to protect against air entry, the powders are mixed for 25 hours, and after the powder mixing is completed, the FeCoNbW alloy powder is taken out;

[0050] The remaining steps and parameters remain the same.

[0051] The performance of the FeCoNbW alloy targets prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was tested:

[0052] Archimedes was used to measure the density of the target material;

[0053] The metallographic microscope was used for observation, and the intercept method was used to calculate the average grain size;

[0054] Test the magnetic permeability (PTF) according to ASTM F2086-01 standard;

[0055] Purity was tested using GDMS.

[0056] The test results are shown in Table 1:

[0057] Table 1

[0058]

[0059]

[0060] As can be seen from Table 1, by adjusting the ratio of the content of each element in the FeCoNbW alloy target and hot pressing and sintering at 1300°C, the finished FeCoNbW alloy target prepared in Examples 1 to 5 has precise composition control, uniform composition distribution, high purity and high magnetic permeability, is suitable for magnetron sputtering, and has good soft magnetic properties; Comparing Example 1 with Comparative Example 1, the hot pressing and sintering temperature of Comparative Example 1 is relatively low, resulting in poor density of the alloy target, but the magnetic permeability remains at a good level; Comparing Example 1 with Comparative Example 2, the hot pressing and sintering temperature in Comparative Example 2 is too high, although the density is good, the grains grow abnormally, resulting in low magnetic permeability; Comparing Example 1 with Comparative Example 3, the alloy target prepared by directly mixing the alloy powders in 4 has good properties such as density and purity, but poor magnetic permeability.

[0061] The present application limits the powder mixing method of the alloy target material and adopts the vacuum hot pressing sintering method to help form a uniform whole inside the powder and avoid cracking of the target material. The temperature and pressure are precisely controlled by vacuum hot pressing sintering to achieve regulation of the microstructure of the alloy target material, which is beneficial to shrinkage and improve the organizational structure of the alloy, avoid oxidation of the material and contamination by impurities, and reduce energy consumption and production costs.

[0062] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0063] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hot pressing method for preparing a FeCoNbW alloy target, characterized in that: The following steps are involved: Step 1, vacuum melting Fe blocks, Co blocks, and Nb blocks and then atomizing them to obtain FeCoNb alloy powder; Step 2, FeCoNb alloy powder and W powder are mixed to obtain FeCoNbW alloy powder, which is subjected to mold filling, vacuumization, hot pressing sintering, and machining in sequence to obtain FeCoNbW alloy target; The specific sintering process of hot pressing sintering is as follows: Under vacuum conditions, the temperature is increased from room temperature to 950-1050°C at a first heating rate and kept at this temperature for 50-70 min; the temperature is then increased to 1100-1200°C at a second heating rate and kept at this temperature for 50-70 min; the temperature is then increased to 1300-1400°C at a third heating rate, and the pressure is increased during the heating process. When the temperature is reached, the pressure is increased to 35 MPa, and the temperature and pressure are kept and calcined for 90-120 min; after sintering, the temperature and pressure are reduced along with the furnace to ≤200°C.

2. The hot pressing preparation method of a FeCoNbW alloy target according to claim 1, characterized in that: The mass percentage of elements in the FeCoNbW alloy target is Fe: 10-20at%, Nb: 4-6at%, W: 10-20at%, and the balance is Co.

3. The hot pressing preparation method of a FeCoNbW alloy target according to claim 1, characterized in that: The atomization pressure of gas atomization is 3.6MPa, the atomization temperature is 1650°C, and the atomization gas is argon.

4. The hot pressing preparation method of a FeCoNbW alloy target according to claim 1, characterized in that: The oxygen content of the FeCoNb alloy powder is ≤500ppm and the particle size is -200 mesh.

5. The hot pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The purity of W powder is ≥3N5 and the particle size is -325 mesh.

6. The hot pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The powder is mixed using a V-type powder mixer, filled with argon gas for protection, and the mixing time is 20-30 hours.

7. The hot pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The mold used for the mold is a graphite mold, the flatness of the mold is less than 1mm, and a tungsten foil is placed between the FeCoNbW alloy powder and the mold.

8. The hot pressing preparation method of a FeCoNbW alloy target according to claim 1, characterized in that: Evacuate to a vacuum degree of <100Pa.

9. The hot pressing method for preparing a FeCoNbW alloy target according to claim 1, characterized in that: The first heating rate is 9-11°C / min, the second heating rate is 4-6°C / min, and the third heating rate is 3-4°C / min.

10. A FeCoNbW alloy target, characterized in that: Prepared by the preparation method according to any one of claims 1 to claim 9.

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