JPH052721B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a dense sintered body of rare earth metal-containing Fe-based or Co-based metal powder by the HIP method.

[Conventional technology]

In recent years, the technological progress of magneto-optical recording has been remarkable, and the development of magneto-optical disks is being actively carried out mainly to improve the performance of magneto-optical recording media. Materials for recording media include TbFeGdTbFe, TbFeCo,
A thin film medium having a composition such as GdDyFeCo is used and is formed on an acrylic or epoxy substrate by sputtering or the like. The magneto-optical recording thin film medium formed by this sputtering method has uniformity of components,
High purity and low oxygen content are required. Therefore, substrate materials with high density, high purity, and low oxygen content are required as sputter target substrates. Furthermore, due to problems in mass production, sputter target substrates are shifting from φ4 inches, φ6 inches, etc. to large rectangular substrates such as 5 inches×12 inches.

Conventionally, as methods for manufacturing sputter target substrates, methods such as casting and hot pressing using pulverized powder have been known for a long time. However, although the casting method can produce large substrates, internal defects such as cavities are likely to exist inside the material, and the hot pressing method uses a pressing mold, so there is a limit to the pressure, and it is difficult to achieve high density and large diameter substrates. The problem is that the substrate is difficult to fabricate and is unsuitable for mass production.

As a way to overcome this fatal flaw,
The HIP method using containers is known. To explain this simply, in Fig. 2, a rectangular container 1 is filled with metal powder 2 and subjected to HIP treatment.
A high-density sintered body 3 after HIP treatment as shown in the figure is obtained, and all six sides of this sintered body 3 are flattened by cutting, cutting, polishing, etc. as shown by the broken line in Figure 2. A target substrate 4 is obtained.

[Problem that the invention seeks to solve]

The rare earth metals contained in sputter targets for magneto-optical recording are rare metals and quite expensive.
Material costs account for the majority of the product price.
If the conventional HIP method using a container is simply used, the material yield is very poor. Therefore, it is essential to increase material yield and manufacture products efficiently.

It is an object of the present invention to provide a method for manufacturing products with a high yield, particularly from large rectangular substrates.

Furthermore, the present invention provides a method for easily producing large prismatic high-density sintered bodies of Fe-based or Co-based alloys containing rare earth metals, particularly sputter target substrates, using the HIP method with good yield. The purpose is also to

[Means for solving problems]

According to the present invention, in the method of filling a cylindrical metal container having a central axis with metal powder, deaerating and sealing the container, and then subjecting the container to hot isostatic pressing at high temperature and pressure, A pair of metal dummies having opposing surfaces along the central axis of the cylindrical metal container on both sides of the metal powder are used as spacers to form a sandwich-like structure,
A hot isostatic press forming method characterized by producing a square high-density sintered body is obtained.

[Effect]

According to this, after the HIP treatment, only the surface of the metal powder that contacts the container shows non-uniform deformation, and the surfaces that contact the upper and lower metal spacers become flat surfaces without showing non-uniform deformation. Therefore, a square substrate can be obtained by cutting, grinding, polishing, etc. only the side surfaces.

〔Example〕

Examples of the present invention are shown below.

Referring to FIG. 1, two spacers 7 made of mild steel and having a semicircular cross section coated with a mold release agent (BN) are charged into a cylindrical container 6 made of mild steel coated with a mold release agent (BN). After that, in the center of the container 6, place 2 pieces of GdTbFe alloy powder pulverized to 30 meshes.
Fill it with. A lid with an exhaust pipe (not shown) is then welded to the container 6. In this state, connect the exhaust pipe to the vacuum pump and heat the inside of the container to 1000℃
A heating vacuum treatment was performed under the conditions of 2H and 3×10 ^-6 Torr. After heating and evacuation, a part of the exhaust pipe was heat-pressed while continuing vacuum degassing, and then the exhaust pipe was cut and a sealed container was produced.

This sealed container is placed in a HIP furnace and the temperature
Under the conditions of 1600℃ pressure 1000 atm and holding time 3 hours
HIP treatment was applied. The sealed container after HIP treatment is indicated by symbol 8 in FIG.

The sintered body, ie, the GdTbFe alloy, taken out from the container 8 after such a process is shown by the symbol 9 in FIG. According to this alloy 9, only the sides are cut,
By simply polishing and lightly polishing the top and bottom surfaces, a large square high-density sintered body [(2~8) inches x (9~
20.4) inches x (3-10) mm], i.e.
A sputter target substrate 10 could be manufactured.

Further, the structure of GdTbFe alloy 9 was a high-density material with a relative density of 99.6% without defects such as voids and cracks. In addition, when the oxygen content was measured, it was found to be 820 ppm.
The oxygen content was equivalent to 850 ppm.
When this material was brazed to a conductive metal, a sputter target was prepared, and a sputter film was formed, a good magneto-optical recording medium film was obtained.

The spacer is preferably made of a material with a melting point equal to or higher than the HIP treatment temperature, and is usually made of mild steel, stainless steel, or the like.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily obtain a large prismatic high-density sintered body with a good yield.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a hot isostatic pressing method according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a conventional hot isostatic pressing method. 2... Metal powder, 6... Cylindrical container, 7...
...Spacer, 8...Sealed container, 9...
GdTbFe alloy, 10... Sputter target substrate.

Claims (1)

[Claims] 1. A method in which a cylindrical metal container having a central axis is filled with metal powder, the container is degassed and sealed, and then the container is subjected to hot isostatic pressing at high temperature and pressure. , a pair of metal dummies having opposing surfaces along the central axis of the cylindrical metal container on both sides of the metal powder are used as spacers to form a sandwich-like structure to produce a square high-density sintered body. Hot isostatic press molding method. 2. The hot isostatic press forming method according to claim 1, characterized in that Fe-based or Co-based metal powder containing a rare earth metal is used as the metal powder.