Claims
- 1. Alloy powder for manufacturing a metal target, each particle of the powder having a two phase structure in which an .alpha.-phase of at least one rare earth metal and an intermetallic compound phase composed of said at least one rare earth metal and at least one iron group metal are uniformly and finely dispersed.
- 2. The alloy powder as in claim 1 wherein the alloy is a eutectic alloy of said one rate earth metal and said one ion group metal.
- 3. The alloy powder as in claim 1 wherein said one rare earth metal is selected from the group consisting of Tb and Dy and wherein said one iron group metal is Fe.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 62-97057 |
Apr 1987 |
JPX |
|
BACKGROUND OF THE INVENTION
This is a division of application Ser. No. 07/183,993, filed Apr. 20, 1988, now U.S. Pat. No. 4,957,549.
The present invention relates to alloy powder for rare earth metal-iron group metal targets for magneto-optical recording media, a rare earth metal-iron group metal target and methods of producing them.
Recently, vigorous development has been being conducted to provide a magneto-optical disk, which is a rewritable, high-density recording medium, formed by sputtering a thin layer composed of rare earth metals and iron group metals in a desired composition on a glass or plastic disk substrate. Targets used in the sputtering are conventionally produced by various methods as follows:
However, all of the above methods suffer from various problems. Specifically, when a target is produced by the method (1), the following problems take place:
(d) When a target produced by this method (1) is used for sputtering to form a thin layer for a magneto-optical disk, the thin layer tends to have a composition which is richer in an iron group metal by nearly 7-10 atomic % than the desired composition, making it difficult to control the composition of the resulting thin film.
When a target is produced according to the method (2), a homogeneous target can be obtained, but the same problems as those of targets produced by the above method (1) exist because alloy particles per se are composed of brittle intermetallic compounds.
With respect to the method (3), the following problems exist:
Last, when the above method (4) is used, specifically when iron group metal-rare earth metal alloy powder is mixed with about 1-10 weight % of an iron group metal to provide a powder mixture having a desired composition which is then pressed and sintered, as shown in Example of Japanese Patent Laid-Open No.60-230903, the following problems take place:
Japanese Patent Laid-Open No.62-70550 discloses a target substantially free from all problems inherent to the above-mentioned conventional technologies, and has a fine mixed structure in which intermetallic compounds of rare earth metals and iron group metals are bonded with iron group metals by sintering. More specifically, this target having the above structure is obtained by mixing rare earth metal powder with iron group metal powder in a desired proportion, subjecting the resulting mixture to pressure sintering at a temperature lower than a liquid phase-appearing temperature to form a sintered body composed of rare earth metals and iron group metals, and then heating it at a temperature equal to or higher than the liquid phase-appearing temperature for a short period of time to convert the rare earth metals in the sintered body into intermetallic compounds.
With this target, the rare earth metals take a shorter time to sputter when they are converted into metallic compounds than when they are not chemically bonded, and so their sputtering rate becomes closer to that of the iron group metals. As a result, the problem of unstableness in composition of a sputtered thin layer which has been pointed out conventionally can be solved, and the target has strength which sufficiently ensures mechanical workability due to the iron group metals contained therein.
It has been found through investigations by the inventors, however, that the technology of Japanese Patent Laid-Open No.62-70550 still suffers from the following problems:
Therefore, an object of the present invention is to provide rare earth metal-iron group metal target alloy powder free from the above problems inherent to the conventional technologies and enabling stable sputtering.
Another object of the present invention is to provide a rare earth metal-iron group metal target having good sputtering properties and sufficient mechanical strength without suffering from the above problems.
A further object of the present invention is to provide a method of producing such a target.
A still further object of the present invention is to provide a method of producing such alloy powder.
As a result of intense research in view of the above objects, the inventors have found that such a target free from the above problems can be obtained by conducting a rapid quenching treatment such as a gas atomizing method to prepare rare earth metal-iron group metal alloy powder in which an .alpha.-phase of rare earth metals and intermetallic compounds are uniformly and finely precipitated, and iron group metal powder, and subjecting their mixture to pressure sintering at a temperature lower than a liquid phase-appearing temperature. The present invention is based on this finding.
Thus, the rare earth metal-iron group metal target according to the present invention has a structure in which a eutectic alloy phase composed of the rare earth metal and the iron group metal and an iron group metal phase are bonded with each other via a diffusion bonding layer consisting essentially of a rare earth metal-iron group metal intermetallic compound.
The alloy powder for a rare earth metal-iron group metal target according to the present invention has a structure in which an e-phase of the rare earth metal and an intermetallic compound phase composed of the rare earth metal and the iron group metal are uniformly and finely dispersed.
The method of producing a rare earth metal-iron group metal target according to the present invention comprises the steps of mixing powder produced by the rapid quenching treatment of an alloy composed of at least one rare earth metal and at least one iron group metal in a composition range which permits the formation of an eutectic structure, with the powder of at least one iron group metal in an amount necessary for meeting the composition requirements of the target; and subjecting the resulting mixture to pressure sintering in vacuum or in an inert gas atmosphere at a temperature lower than the liquid phase-appearing temperature of the mixture.
The method of producing alloy powder for a rare earth metal-iron group metal target according to the present invention comprises subjecting an alloy melt composed of at least one rare earth metal and at least one iron group metal in a composition range which permits the formation of a eutectic structure to a rapid quenching treatment.
US Referenced Citations (3)
| Number |
Name |
Date |
Kind |
| 3928089 |
Cech |
Dec 1975 |
|
| 4620872 |
Hijikata et al. |
Nov 1986 |
|
| 4957549 |
Matsumoto et al. |
Sep 1990 |
|
Foreign Referenced Citations (10)
| Number |
Date |
Country |
| 59-162250 |
Sep 1984 |
JPX |
| 60-230903 |
Nov 1985 |
JPX |
| 61-91336 |
May 1986 |
JPX |
| 61-95788 |
May 1986 |
JPX |
| 61-99640 |
May 1986 |
JPX |
| 61-119648 |
Jun 1986 |
JPX |
| 61-139637 |
Jun 1986 |
JPX |
| 62-70550 |
Apr 1987 |
JPX |
| 62-274033 |
Nov 1987 |
JPX |
| 63-50469 |
Mar 1988 |
JPX |
Non-Patent Literature Citations (2)
| Entry |
| "Mikkei New Materials", p. 61, Nov. 24, 1988. |
| Summary of lectures in 10th Academic Meeting of Japan Applied Magnetics Association, pp. 128-129, 1986. |
Divisions (1)
|
Number |
Date |
Country |
| Parent |
183993 |
Apr 1988 |
|
Patent Grant
5062885
