JPH01156404A - Method for sintering rare earth element-contained metal - Google Patents

Abstract

PURPOSE:To obtain a sintered body having only a little oxygen contamination bp packing rare earth element-contained metal powder in a metal-made container, air-tightly sealing after charging getter material in a separated chamber spacely communicating with the container and executing hot hydrostatic press at high temp. and high pressure. CONSTITUTION:The rare earth element-contained metal powder is packed in the metal-made container and after vacuum exhausting in the inner part, it is air-tightened. Successively, the container is treated with the hot hydrostatic press at high temp. and high pressure. In the sintering method for the rare earth element-contained metal powder, at the same time of packing the metal powder to be sintered, in the separated chamber spacely communicating with the above powder to be sintered, arranged in the container, target material composing of the rare earth metal, Ti, Zr or alloy powder containing these as main component is charged. This separated chamber is to have a larger strength than the container. By this method, the oxidation at the time of sintering is prevented and the sintered material having only a little contamination is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for producing a sintered body of transition metal powder containing a rare earth metal by a hot isostatic pressing (hereinafter abbreviated as HIP) method. It is related to.

[Conventional technology]

In recent years, interest in magneto-optical recording has increased significantly, and magneto-optical disks have been actively developed.

Magneto-optical recording is a method of recording by exposing a magnetic material to light and a magnetic field.
A magnetic thin film is used.

Materials for the magnetic thin film include transition metal-rare earth systems, binary systems such as Fe-Gd and Fe-Tb, Fe-
Three elements such as -Co-Tb, Fe-Gd-Tb, etc. are considered to be promising.

Magneto-optical disks are produced by forming the above-mentioned magnetic thin film material on the surface of a circular base made of synthetic resin or the like using the PVD method.

In the PVD method, a film is generally formed using a sputtering device. This 4-Tutter device requires an alloy target having a composition approximately equal to that of the magnetic thin film, and the transition metals and rare earth metals in this target are deposited on the circular substrate.

Alloy targets are divided into cast targets and sintered targets based on their manufacturing method.

Traditionally, transition metal-rare earth alloys were extremely brittle, making it difficult to create large-area targets suitable for mass production.

It was common to manufacture alloy targuts by a powder metallurgy method called sintering. The hot press method is a common powder metallurgy method, but since it uses a pressing die to produce β-shaped materials, the pressure is limited, making it difficult to manufacture dense and complex targuts with a β-shape.

In recent years, the HIP method, which has been used in the development of superhard materials and has received increasing attention, performs high-temperature and high-pressure processing using Ar gas as a pressure medium.
A high pressure of 0,000 atmospheres can be obtained, and large-sized, high-density targuts can be manufactured.

The HIP method involves filling a mild steel or stainless steel capsule with an alloy powder obtained by crushing Inco 9t melted to a predetermined composition or a powder of the base metal that forms the alloy.
After creating a high vacuum of Torr or higher and heating at 300° C. or higher to remove moisture and residual gas inside the container, the container is sealed while maintaining the vacuum.

This container is placed in a pressure medium such as high-temperature and high-pressure Ar gas,
Obtain a high-density sintered body.

Although the target material thus obtained has a high density and relatively high strength, it has a high oxygen content, and when used as a magnetic thin film material, the magnetic properties are deteriorated, which is not preferable.

[Problem that the invention seeks to solve]

Oxidation in the target material manufacturing process by the sintering method includes oxidation in the process up to powder and oxidation in the HIP process.

Among these oxidations, in the present invention, oxidation (
In the conventional method, an increase in oxygen concentration of about 500 to 1000 ppm was observed. ).

[Means for solving problems]

In view of the above problems, the present invention has been developed by simultaneously putting a getter material into the container used during HIP processing.
This prevents contamination of the sintered body. The place where the getter material is placed needs to be in a separate room that is spatially connected to prevent it from mixing with the object to be sintered (see Figure 1).

In addition, the getter material entering this separate chamber must be sintered more slowly than the object to be sintered, and for this reason, the strength of the separate chamber must be greater than that of the container. Specifically, in Figure 1, the patch plate 2, which is much thicker than the container material,
3 is installed in a container 1, the bottom side patch plate 3 has a two-layer structure, a recess 7 is provided between the two patch plates, and the structure is connected to the raw material powder through an air passage 6.

As the getter material, rare earth metals, Ti, Zr, or alloy powders containing these as main components are used, but iron-rare earth alloy powder or Ti powder is preferable from the viewpoint of easy availability. Further, the less oxidation and the finer the particle size of the getter material powder, the better.

[Effect]

As the HIP process progresses, high temperature and pressure are applied to the container containing the objects to be sintered, causing it to deform. At this time, the space inside the container is filled with gas that could not be removed by vacuuming when the container was sealed, and gas that was newly generated due to high-temperature heating by HIP. It is guided to a separate chamber with a high ceiling and where deformation is the slowest, and is absorbed by the getter material.

〔Example〕

■Iron 96 is produced using a vacuum arc furnace with molten tungsten electrodes.
6.9. Cobalt 118F and terepium 916I were melted to obtain Fe-Co-Tb alloy 1950.9.

Note that the vacuum arc furnace was replaced with high-purity Ar before melting.

As raw metals, 99.99% electrolytic iron and commercially available 99.94Co and 99.8% Tb were used.

(2) Grinding The above Fe-Co-Tb alloy was ground in a stainless steel mortar under an Ar atmosphere. After pulverization, sieving is performed to obtain a particle size of 3.
00~150μ, 150~100μ, 100~45μ,
It was classified under 45μ.

Table 1 shows the results of analyzing these oxygen concentrations.

Table 1: Oxygen concentration of pulverized powder (■) Molding Next, the above alloy powder was sampled from each particle size, mixed as shown in Table 2, and filled as shown in FIGS. 1 and 2.

In addition, Tt powder as a getter material in Table 2 is a commercially available product.
It was sieved under 5μ.

Table 2 After filling the powder, the lid and container were melted while flowing Ar from the vacuum pipe, and then vacuumed for 9 days. When the pressure was reduced to 3 x 10-' Torr, the temperature was raised to 200 °C. After heating and holding for 5 hours, the container was sealed while maintaining vacuum.

■Sintering Put the above container into a HIP device at 1000℃ x 1000
The mixture was maintained at a temperature and pressure of kg/yr;' for 4 hours.

After removing the container from the HIP apparatus, it was opened, and a portion of the obtained sintered body was analyzed. (See Table 3) Thereafter, the sintered body was finished into a 101.6" x 5t plate and used as a target plate.

The sintered body was dense with no pores, and no defects such as cracks, cracks, or cracks were observed.

(Yo T-Ko 6) [Effect] The results of the above experiment show that the oxygen concentration of the target material in the container containing the getter material hardly increases before and after the HIP treatment.

Furthermore, this method is applicable not only to transition metal-rare earth metals but also to sintering of other easily oxidizable metals by HIP.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the loading method of the present invention, and FIG. 2 is a diagram for explaining the conventional loading method.

Claims (1)

[Claims] 1. In the sintering method for rare earth-containing metals, which involves filling a metal container with metal powder, sealing it, and then subjecting the container to hot isostatic pressing at high temperature and pressure, the sintered object is simultaneously placed inside the container. A separate chamber spatially connected to the sintered body is provided, and a getter material made of rare earth metals, Ti, Zr, or alloy powders containing these as main components is placed in this separate chamber and hot isostatic pressing is performed. A method for sintering rare earth-containing metals.