JPS6256543A - Manufacture of sintered compact of rare-earth alloy - Google Patents

Abstract

PURPOSE:To easily manufacture a target made of sintered compact or rare-earth alloy free from defects and having high density by refining an alloy having a specific composition consisting of rare earth elements, Fe and Co, crushing the above, charging the resulting powdered alloy into a mold for compacting and then subjecting it to compacting and sintering under specific conditions. CONSTITUTION:The prescribed alloy is refined previously so as to provide a composition consisting of 10-80wt% of one or more among rare earth elements including Y and the balance essentially Fe and/or Co, which is crushed and regulated. Thus-obtained powder is charged into the mold for compacting, which is subjected to compacting and sintering at a temp. ranging from the liquidus temp. of the above alloy to +50 deg.C, at a pressure of >=500kgG/cm<2> and under the condition where the above powder of rare-earth alloy is allowed to exist in a practically inert or vacuum atmosphere. In this way, the high- density sintered compact of rare-earth alloy for targets suitable for sputtering operation can be obtained in a short time without causing the occurrence of cracks, breakage, etc., nor causing any problem in handling.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the production of a rare earth alloy sintered body, and more specifically, to the production of a rare earth alloy thin film that can be used as a recording medium in a magnetic disk in a magneto-optical recording system. The present invention relates to a method for manufacturing a target material (rare earth alloy sintered body) to be attached to a sputtering device when forming the target material.

(Prior Art) Generally, sputtering is used as a thin film forming method for various purposes, and therefore, the materials of targets used in sputtering devices are diverse, including various metals, alloys, ceramics, etc. In addition, the shape and dimensions of the target are generally from several μm to more than ten μm in thickness.
It has a rectangular or circular shape consisting of a flat plate.

To manufacture targets from such materials, in the case of metals or alloys, the base material must be forged and then rolled, or the base metal molten metal must be cast, and then finishing processing such as cutting and polishing is performed as necessary. It is common to obtain the target by applying

Furthermore, when ceramics are used as the material, it is common to form the powder, sinter it, and then finish it by cutting, polishing, etc.

By the way, in magnetic disks using magneto-optical recording systems, magnetic thin films made of rare earth alloys are being used as recording media. When producing this rare earth alloy thin film by sputtering, it is preferable to use a rare earth alloy as a target.

However, alloys containing rare earth elements, especially rare earth alloys with a composition range of 10 to 80% rare earth elements, with the balance being Fe and/or CO, have extremely fragile casting structures, so the above-mentioned It is difficult to manufacture target plates using processing methods applied to general metal materials such as metal materials.

Therefore, attempts have been made to apply the powder metallurgy method as another manufacturing method, but there are problems in that it is particularly difficult to manufacture and handle, as the molding as a target and the sintered body may crack or chip. . In addition, an expedient method has been attempted in which small pieces of multiple types of pure metals are arranged on the target site and adjusted by the ratio of each metal (component) to the surface area, without using it as an alloy. It cannot be expected to have an effect comparable to that of the target.

(Object of the Invention) The present invention solves the drawbacks of the above-mentioned conventional technology, and when manufacturing the above-mentioned rare earth alloy target by applying a powder metallurgy method,
No cracks, chips or falling off.

It is an object of the present invention to provide a method for obtaining targstone l-plates suitable for sputtering operations without production and handling problems.

(Structure of the Invention) In order to achieve the above object, in the present invention, the rare earth alloy powder is formed and sintered under specific conditions.

The present invention will be explained in detail below based on examples.

The material used in the method of the present invention is a rare earth element containing Y (hereinafter referred to as
The total of one or more types of rare earth elements (referred to as rare earth elements) is 10~
It has a composition of 80% by weight, and the remainder substantially consists of one or two of Fe and CO.

Rare earth elements include lanthanum series elements such as La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb
, Dy, HOlEr, Tm, Yb and Lu. However, Y is included. These elements can be contained alone or in combination of two or more, and the content is 10 to 80% by weight within a range that allows formation of a magnetic thin film with desired characteristics by sputtering.

Note that the rare earth element is preferably used in the form of an alloy or a master alloy.

The remainder of the rare earth element content is Fe and/or Go.
It is necessary to control the impurity components to an extremely small amount. In particular, in view of the fact that rare earth elements are active in oxygen,
Take care to avoid mixing as much as possible.

In the present invention, materials having these compositions are prepared by melting one or more rare earth alloys having the target chemical composition in advance and then pulverizing them, or by melting a base rare earth alloy in advance and then pulverizing them. The composition is adjusted by mixing one or more types of pure metal powder of other alloy components into the powder. Of course, it is also possible to mix two or more types of rare earth alloy powders with different component compositions, and in this case, the component composition as a target can be freely selected, and the sputtering thin film obtained can be made better than by simply mixing each component. The magnetic properties of the material are improved. In particular, the magnetic properties of the sputtered thin film are better when rare earth elements are used in the form of an alloy rather than mixed as a single powder.

Next, in the method of the present invention, the powder whose composition has been adjusted is charged into a mold for molding, and processed under the molding and sintering conditions shown below.

That is, the molding pressure is set to a value of 500 kgG/cm2 or more in order to increase the sintering force and facilitate sintering.

The sintering temperature is selected within the range of −+50° C., the liquidus point of the rare earth alloy, in order to perform complete liquid phase sintering or partial liquid phase sintering. Especially when using two or more types of alloy powder,
By sintering one in a liquid phase and the other in a solid phase L9-, liquid phase sintering is also possible in part.

The sintering atmosphere is an inert atmosphere or a vacuum atmosphere considering that rare earth elements are active, but there is no particular problem as long as the vacuum state is maintained. Of course, it goes without saying that the holding time at the above temperature determines the time suitable for sintering in a completely liquid phase or a partially liquid phase.

The above molding and sintering conditions are hot press (HP) method,
It goes without saying that it can be applied to any case of the hydrostatic hot press (HIP) method. I-IP method is HIP
Although pressure and temperature restrictions are greater than in the case of the method, and the density ratio of the obtained sintered body is small, it is possible to ensure sufficient strength for use.

(Example) 500 g of each rare earth alloy having the composition shown in Table 1 was melted using a known vacuum arc melting apparatus having a water-cooled steel hearth and a tungsten electrode. In addition.

Prior to melting, the sample was evacuated to 3 x 10-' Torr, then the pressure was increased to 400 Torr with purified high-purity Ar gas, and melted at an arc voltage of 20V. In addition, as raw material metals,
Iron with a purity of 99.99% obtained by vacuum arc melting of electrolytic high-purity iron, nickel with a purity of 99.95% obtained by processing electrolytic high-purity cobalt in H2 at 900°C and vacuum degassing treatment, Commercially available high purity rare earth elements (purity 99.5%) were used.

Table 1 Rare earth alloy composition (wt%) ■ Grinding The solidified alloy after vacuum arc melting was ground in a stamp mill in a high-purity Ar atmosphere. The specifications of the stamp mill are as follows.

Pestle weight...3, 8 kg Stroke...100mII Number of falls: 20 times/min All pulverized materials had a diameter of -150 μm.

■Forming Next, after mixing and adjusting one or two types of rare earth alloy powders having the composition shown in Table 1 as shown in Table 2, each sample material was filled into a capsule used in the HIP method. A layer thickness of approximately 7+ nm was obtained. The capsule is a mild steel type with a plate thickness of 1.5 mm.
It is cylindrical with an inner diameter of 60+nm and a depth of 20cam, and the lid has a diameter of 59.8mm and an outer diameter of 4IIIl in the center.
I prepared one with a φ vacuum pipe attached.

After filling the pulverized material, put the lid on the capsule, flow Ar gas from the vacuum pipe, and connect the lid and the capsule body with T.
The capsules were joined without any gaps by IG welding, and then the vacuum pipe was connected to a vacuum pump, and the entire capsule was heated to 120° C. and the pressure was reduced to >3×10 −4 Torr. When a predetermined vacuum was reached, the vacuum pipe was burned out with a gas burner, and the capsule was sealed.

■The sample sealed in the sintered capsule is pressurized and heated in a hydrostatic hot press under the conditions (pressure, temperature level, and holding time) shown in Table 2, then slowly depressurized, slowly cooled, and removed from the device. Ta. Next, after removing the capsule, the obtained sintered body was finished with a surface finish and circumference using a grinder, and the plate thickness was 5.
．． A target plate with a diameter of 0 mm and a diameter of 50 ma+ was used.

Table 2 also shows the results of examining the density ratio (l-porosity) of each sintered body, as well as the presence or absence of in-plane cracks and the presence or absence of chipping during finishing.

[Margin below] As shown in Table 2, the test materials of all component compositions had no defects such as in-plane cracks or chips, and were sound and extremely dense sintered bodies. The transverse rupture strength of some of the sintered bodies was measured, and values sufficient for use as targets were obtained.

The method of the present invention described above can be similarly applied to target materials in which other elements are added to the rare earth alloy for the purpose of improving the film properties of thin films obtained by sputtering, and good results can be obtained. .

(Effects of the Invention) As detailed above, according to the present invention, the rare earth alloy of the target material is melted and pulverized in advance, and then pressure sintered under specific conditions to produce the sintered material for the target. Since a solid body is obtained, it is easy to manufacture, particularly in a short processing time, there are no handling problems, and it is possible to provide an extremely high-density target suitable for sputtering operations. In particular, there is an advantage that the component composition of the target can be selected arbitrarily, and the magnetic properties of the sputtered thin film can be improved from a manufacturing standpoint.

Claims (1)

[Claims] Contains 10 to 80% by weight of one or more rare earth elements (including Y), with the remainder being substantially Fe and C.
The required alloy is melted and pulverized in advance so that it has a composition consisting of one or two of the following: A sputtering target characterized by pressurizing and sintering the rare earth alloy powder in a substantially inert or vacuum atmosphere at a temperature of +50°C and a pressure of 500 kgG/cm^2 or more. A method for manufacturing a rare earth alloy sintered body for use.