JPH0524210B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a second phase metal particle dispersed alloy in which fine second phase metal particles are uniformly dispersed in a matrix. Conventionally, a casting method has been known as a method for manufacturing alloys in which second phase particles such as oxides and carbides are dispersed in the alloy matrix, but the cooling rate of this casting method is approximately
It is extremely slow at 10℃/sec, and oxides and carbides have poor wettability with molten metal, and the difference in specific gravity is large. There were many problems such as large segregation and localized decrease in wear resistance.
The alloy produced by this casting method has poor dispersion, so the proximity effect does not appear, and particularly excellent properties such as superconductivity were not found. In addition, as a method of manufacturing an alloy in which second phase metal particles are dispersed in the alloy matrix, for example, a method of casting an Al-Pb alloy with a water-cooled casting mold (Japan Institute of Metals Autumn Conference 1983.10. General Lecture Abstracts P. 376) ) has been proposed. However, even in the casting method using water-cooled molding, the cooling rate is low at about 10 ² °C/sec or less, so the Pb particles generated in the matrix are extremely large, over 500 μm, and there is a large variation in particle size. However, it was distributed non-uniformly, and the strength was highly uneven in terms of properties, and particularly excellent properties such as superconductivity were not fully expressed. As described above, the dispersibility of the second phase particles of the alloy obtained by the above-mentioned casting method was very poor, but this alloy is specially designed to improve the dispersibility of the second phase metal particles in the alloy. There are JP-A-59-47341 and JP-A-59-47352. In this publication, as a method for producing amorphous alloys and non-equilibrium crystalline alloys, the examples include dispersing second phase particles using a liquid quenching method that has been attracting attention in recent years. WC, TiC, BN with particle size 1μm, particle size 2μm
An alloy is described in which ThO ₂ , SiC with a particle size of 3 μm, NbN, and Fe particles with a particle size of 5 μm are uniformly dispersed in an amorphous or crystalline matrix. The feature of this alloy is that second phase particles (e.g. carbides, oxides, metals, alloys) that are incompatible with the molten metal are mixed with the molten metal and then rapidly solidified using a liquid quenching method. In this method, the second phase particles are mixed together, the mixture is rapidly solidified, and the mixture is uniformly dispersed. However, since the particle size and dispersibility of the second phase particles contained in the alloy obtained by this manufacturing method have been improved from a conventional perspective, the alloy is tough and has high strength. However, as mentioned above, the particle size is still large at 1 to 5 μm, and the dispersibility has large variations in the distance between nearest adjacent particles of 1 to 100 μm, so strength unevenness tends to occur, and it is still insufficient. I can't say that. That is, since the molten metal before being rapidly solidified is a mixture of the molten alloy and various solid particles, the particle size of the second phase particles is also on the micro-order. However, there was naturally a limit to the dispersibility of the second phase particles. As a result of intensive research aimed at obtaining a structure in which second-phase metal particles, which are even finer than those of conventional second-phase particle-dispersed alloys, are uniformly dispersed in the matrix, the inventors found that two-phase separation We have discovered that the above objective can be achieved by rapidly solidifying a compatible single-phase liquid alloy by a liquid quenching method.
The present invention was completed based on the discovery that the obtained second phase metal particle dispersed alloy has no unevenness in strength and has excellent properties such as superconductivity. That is, the present invention is characterized by melting an alloy that separates into two phases to obtain a compatible single-phase molten metal, and then rapidly solidifying the obtained molten metal by a liquid quenching method. This is a method for producing a second phase metal particle dispersed alloy having an excellent superconducting property and having a structure in which metal particles are uniformly dispersed. In the present invention, it is first necessary to melt an alloy that separates into two phases to obtain a compatible single-phase liquid molten metal. For this purpose, for example, an alloy that undergoes two-phase separation,
The alloy may be melted at a temperature 20 to 250°C higher than the melting point of the alloy. In this case, when melting the alloy in the molten metal spouting nozzle, high frequency heating with a molten metal stirring effect is preferable;
A method of suppressing two-phase separation by applying ultrasonic vibrations to the molten metal, or a method of suppressing two-phase separation of the alloy by providing a coil for stirring the molten metal inside in addition to a high-frequency coil for melting also yields favorable results. It is also effective to install a weir or a ceramic filter in the path to the spout hole after melting the alloy in the molten metal spouting nozzle to suppress segregation of alloy components in the molten metal. The alloy that undergoes two-phase separation as used in the present invention refers to an alloy in which the metal element that becomes the second phase metal particles and the main metal element of the parent phase separate into two phases after rapid solidification, and such alloys include, for example, Al-Pb alloy, Al-Pb
-X (X is Si, Sb, Sn, Bi) type alloys. In particular, Al-Pb alloys are preferably alloys containing 1 to 5 atom % of Pb and the remainder substantially Al, while Al-Pb-X alloys are preferably alloys containing 1 to 5 atom % of Pb, Si, Sb, and Sn. , one or more elements selected from the group consisting of Bi, Si5~15
atomic%, Sn10 atomic%, Sb1.1 atomic%, Bi0.8 atomic%
is preferred. By adding Si, the dispersibility of the second phase metal particles is improved and strength unevenness is reduced, and by adding Sb, Sn or Bi, superconducting properties are improved. Next, the liquid single-phase molten metal obtained above is rapidly solidified by a liquid quenching method. This liquid quenching method refers to a method of rapidly cooling a molten metal or alloy to freeze its structure. For example, single roll method, twin roll method, and rotating liquid spinning method are particularly effective, and these methods has a cooling rate of 10 ⁴ to ^{10 6} °C/sec. In order to produce a ribbon material by this single roll method, double roll method, etc., for example, there is no state of liquid-liquid separation, solid-liquid separation, or solid-liquid separation in the molten metal, that is, a completely compatible liquid single phase. Diameter rotating at about 300~10000rpm through the nozzle hole than the state temperature
Spray onto a 30-3000 mm roll made of copper or Cr steel, with a width of about 1-300 mm and a thickness of about 5-30 mm.
A ribbon material of 500 μm can be easily obtained.
In addition, in order to produce fine wire materials by spinning in a rotating liquid, for example, the temperature at which the nozzle hole With argon gas back pressure, the refrigerant is ejected into a refrigerant film with a depth of 1 to 10 cm by centrifugal force inside a drum rotating at 50 to 500 rpm.
Fine wire material can be easily obtained. At this time, the angle between the molten metal spouted from the nozzle and the refrigerant surface is approximately
20~100 degrees, speed ratio between spouting molten metal and refrigerant surface is 0.7~
Preferably it is 0.9. In this way, when the molten state of a single phase of mutually dissolved liquid is rapidly solidified by the liquid quenching method, for example,
In 98Al-2Pb (numbers indicate atomic percent; the same applies hereinafter), there are 40 to 40 Pb particles with a particle size of about 40 nm in the Al matrix.
Transmission electron microscopy revealed that the particles were very uniformly dispersed at intervals of 100 nm.
Similarly, in the 88Al-10Si-2Pb ternary alloy, an alloy in which extremely fine Pb particles are dispersed very uniformly is obtained, with the particle size of the Pb particles being about 30 nm and the interval between the particles being about 100 nm. As described above, according to the present invention, a second phase metal particle dispersed alloy having a structure in which fine second phase metal particles are uniformly dispersed can be obtained, and this alloy has no strength irregularities and has particularly good superconducting properties. It has excellent properties. For example, the Tc (superconducting transition temperature) of pure Al is
1.19K, whereas 98Al-2Pb alloy, which is a second phase metal particle dispersed alloy obtained by the present invention, has a temperature of 4.16K, and 88Al-10Sn-2Pb alloy has a temperature of 4.96K.
Significant improvements were seen in and Tc. This improvement in properties is considered to be due to the proximity effect caused by the fine and uniform distribution of the second phase metal particles. This superconducting property is very useful as a property of various industrial materials such as liquid helium level gauges. Hereinafter, the present invention will be specifically explained with reference to Examples. Examples 1 to 10, Comparative Example 1 Al--Pb alloys and Al--Pb--X alloys having various compositions shown in Table 1 were melted in an argon atmosphere to obtain compatible single-phase liquid molten metals. Next, this molten metal was heated at an argon injection pressure of 3.5 kg/cm ² and a hole diameter of 0.12 mm.
A ruby spinning nozzle of φ is spouted into a rotating cooling liquid with a temperature of 4℃ and a depth of 2cm formed in a cylindrical drum with an inner diameter of 500mmφ rotating at 320rpm and rapidly solidified to form a circular cross section with an average diameter of 0.1mmφ. A continuous thin line with . For comparison, an Al-Pb alloy was also produced by a casting method using a water-cooled mold. The manufacturing conditions were as follows: A copper mold was cooled to 275K in advance, and an 8mmφ ingot was rapidly cast from the temperature at which Al and Pb were compatible. Furthermore, NbN in molten Al
Mix and pass through a 0.3mm nozzle hole at 5000rpm.
Argon was sprayed onto a copper roll with a diameter of 100 mm rotating at a pressure of 3 kg/cm ² to obtain a thin strip sample with a width of 2 mm and a thickness of 40 μm. Al-Pb obtained by the above production method of the present invention
Observation and measurement results of microstructures and superconducting transition temperature (Tc), which is one of the superconducting properties, of Al-Pb-X alloys and Al-Pb-X alloys, Al-Pb alloys manufactured by water-cooled molds, and Al-NbN quenched ribbons. are shown in Table 1. In order to determine the superconducting transition temperature (Tc), we installed the sample inside a cryostat, filled it with dilute helium gas, immersed it in liquid helium, and then measured the electrical resistance of the sample using the usual four-terminal method. . In addition, Pb and Pb dispersed in Al
The particle size and particle spacing of the alloy were observed using a transmission electron microscope.

【table】

[Table] In Examples 1 to 10, the particle size of the second phase metal particles is 10 to 10.
It is very fine at 160 nm, and the interval between the second phase metal particles is extremely uniform at 40 to 150 nm, and the Tc is greatly improved due to the proximity effect. In particular, adding Si reduces strength unevenness, increasing the tensile strength from 2 to 10 Kg/mm2 to 15 to 20 Kg/ ^mm2 .
Kg/mm improved to ² mm. Furthermore, superconducting properties were improved by adding Sb, Sn, or Bi. In addition, alloy materials cast using water-cooled molds are
There were large variations in particle size and dispersibility of the second phase metal particles, almost no proximity effect was observed, and almost no improvement in Tc was observed. In addition, in Comparative Example 2, the second phase particles were large and the uniformity of the particle dispersion was still insufficient in the ribbon material that was rapidly solidified by mixing nitrides that are incompatible with the molten metal, so the proximity effect was not observed. It was not fully expressed.

Claims (1)

[Scope of Claims] 1. A process characterized by melting an alloy that separates into two phases to obtain a molten metal with a single phase of compatible liquid, and then rapidly solidifying the obtained molten metal by a liquid quenching method. A method for producing a second phase metal particle dispersed alloy having excellent superconducting properties and having a structure in which second phase metal particles are uniformly dispersed. 2. The manufacturing method according to claim 1, wherein the alloy that undergoes two-phase separation is an Al-Pb alloy. 3 The alloy that undergoes two-phase separation is Al-Pb-X (however,
X is Si, Sb, Sn, Bi. ) type alloy, the manufacturing method according to claim 1.