JP3095026B2 - Manufacturing method of aluminum sintered alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered aluminum alloy by normal pressure sintering.

[0002]

2. Description of the Related Art Since a strong oxide film that cannot be reduced exists on the surface of aluminum powder or aluminum alloy powder, it is necessary to manufacture an aluminum sintered alloy.
It is necessary to break the oxide film to form a metal contact portion between the powders to allow diffusion of metal atoms.

Conventionally, this method has been roughly divided into the following two methods.

First, as a first method, aluminum or a powder having an alloy component that generates a eutectic liquid phase at a temperature lower than the melting point of the required aluminum alloy composition is mixed as a sintering aid and formed during compression molding. In this method, a liquid phase generated from a metal contact portion between the powders is generated during a temperature rising process, covers the aluminum powder surface, enlarges the metal contact portion, and proceeds with sintering. For example, JP-A-47-34006
Discloses a method for producing a sintered alloy, which comprises sintering a powder compact obtained by mixing Cu or Cu-Sn powder with aluminum powder in a non-oxidizing or reducing atmosphere. Japanese Patent Publication No. 51-13444 discloses a method of adding and compounding a powder of magnesium, zinc or the like as a sintering aid, and Japanese Patent Application Laid-Open No. 50-96409 discloses a method of adding Mg powder as a sintering aid. Alternatively, a method of adding a Cu—Mg master alloy powder as a sintering aid is disclosed. Similarly, JP-B-61-17895, JP-B-61-5485
No. 5, JP-B-61-6243 and JP-B-62-66
No. 26 discloses a method of mixing as elemental powders such as Cu, Mg, Si, and Zn or alloy powders.

As an example of adding Si, Japanese Patent Publication No.
No. 3-118209 discloses a eutectic composition of Al-11.7S.
Al-Si binary alloy powder having a composition near i
Japanese Patent Publication No. 60-38442 discloses a method for producing a sintered body containing a total of 20 to 50% of Si by mixing i powder and alloy element powder as needed.
-Al-Cu-Mg, Al-Cu-Mg to Si alloy powder
-Si, Cu-Mg-Si alloy powder as sintering aid 30
550 ~ 650 ℃ after compression molding
A method for producing a low-density sintered body having a low Si content of 2.1% or less, characterized by sintering in a temperature range of 2.1% or less, has been proposed. JP-A-53-128512 discloses Al-10
A method for producing a high Si-containing sintered body in which Cu, Mg, and Si components are added to and mixed with .about.35Si powder as a single composition powder or an alloy powder. In addition, Japanese Patent Application Laid-Open No. 3-28336 discloses an Al-10 to 45% by weight Si containing 2.0% by weight or less of Cu and 0.5% by weight or less of Mg for the purpose of improving strength.
-The mixed powder obtained by adding a lubricant to the Cu-Mg based alloy powder is sintered again by solid phase diffusion at a temperature not higher than the liquid phase generation temperature and then recompressed. In particular, when the Si content is 20% by weight, after recompression, A method for producing a high Si sintered body to be resintered has been proposed. It is better that the Cu and Mg contents are lower from the viewpoint of sinterability, and in the examples, they are each 0.5% by weight or less.

Next, as a second method, there is a method of manufacturing an aluminum alloy which has been recently developed as a new powder metallurgy technique. This is a method in which a strong plastic working is applied to the powder in order to bond the powder to each other, whereby the powder is plastically deformed, and an oxide film on the surface of the powder is divided to form a metal contact portion. As the plastic working method, hot press method,
There are a powder forging method, a powder extrusion method, a powder rolling method, and the like. For example, JP-A-60-121203 discloses a method of extruding an aluminum alloy powder at a temperature of 250 to 550 ° C. and an extrusion ratio of 4: 1 to 15: 1. JP-A-61-136602 discloses a method of hot-pressing an aluminum alloy powder after heat molding.

[0007]

However, the above two conventional methods for producing a sintered aluminum alloy have the following problems.

First, in the first method of mixing a powder having a synthetic component generating a eutectic liquid phase that plays a role of a sintering aid and sintering after compression molding, the sintering aid is mixed by a mixing method. The eutectic liquid phase is unevenly distributed due to dispersion, unevenness and segregation are likely to occur even in composition, and the homogeneity of the sintered state of the powder is poor, and coarse pores and outflow holes are likely to remain, so high precision -It is difficult to obtain a high-density sintered body. In addition, when an attempt is made to increase the frequency of eutectic liquid phase generation places by increasing the metal contact portion or to increase the compact density in order to improve the dimensional accuracy, for example, a high S
In the case of a hard powder such as i-powder, a high pressure is required. In addition, the sintered body obtained by this method has coarse precipitates formed by rapid solidification, and its mechanical properties are significantly inferior to those of a sintered body formed by a plastic working method.

Further, Al-Si-Cu sintered by solid phase diffusion as disclosed in JP-A-3-28336.
-The sintering method of Mg-based alloy powder can obtain only a low-strength material whose bonding between powders is weak and whose strength does not reach 20 kg / mm ² .

On the other hand, since the sintering by the plastic working method as the second method can be performed in a relatively low temperature range, when quenched and solidified powder is used, high-density sintering which maintains the quenching effect of the powder to some extent is used. Although the properties are excellent because the material can be obtained, the equipment is expensive, the manufacturing cost is high, and the shape is limited, and it is difficult to manufacture the near net shape material, which is a feature of the conventional powder metallurgy, and the material yield is low. Low. Also,
The Al-Si alloy has a small Si crystal diameter in the material, and is inferior in wear resistance as compared with a cast material containing the same level of Si.

According to the present invention, it is possible to obtain a near net shape material which is high in accuracy and density, excellent in mechanical properties and physical properties, and excellent in wear resistance, and which is an advantage of the conventional powder metallurgy method. It is an object of the present invention to provide a method for manufacturing a high-precision aluminum sintered alloy having a high degree of freedom in providing a shape, which can be processed with high precision by sizing or coining if a sintered body having an appropriate amount of pores is distributed. .

[0012]

SUMMARY OF THE INVENTION The inventors of the present invention have conducted intensive studies and, as a result, have found that the conventional method of generating a liquid phase by eutectic reaction and sintering the eutectic liquid phase is an Al powder or an Al powder.
It was found that the sintering was caused at the interface between the alloy powder and the sintering aid. In view of the above, the problem of the sintering method using the sintering additive addition method was solved by inventing a method of sintering without adding and mixing a sintering aid at all. In other words, the present inventors created a liquid phase in each of the powders, thereby distributing the liquid phase in the molded body with high density and uniformity. Here, in order to form a liquid phase in the powder, first, when pulverizing a molten metal having a composition containing Si, Cu, and Mg at the same time, the liquid phase is rapidly solidified to form a liquid phase below the melting point of the required alloy composition. A powder with a metastable phase formed is produced. This alloy can be an alloy whose strength can be improved by heat treatment by containing Si, Cu, and Mg.

According to a further study, the liquid phase generated during the heating step of the above-mentioned powder breaks an oxide film on the surface of the powder, enlarges a metal contact portion, and proceeds with sintering. Thus, even a low-density molded product shrinks uniformly in a short period of time, and succeeds in producing a high-precision, high-density sintered product with extremely small unevenness in composition and segregation. In addition, if the powder is softened by powder annealing within a range that does not impair the generation of the liquid phase, a high-density compact at a low pressure can be obtained, which is effective for improving the precision of the sintered body. It was found that the effect was great when the powder hardness was high in the system.

Further, according to the above-mentioned rapid solidification method, Fe, Ni, M which can be added only in a small amount by the melting method in order to harden the substrate, improve heat resistance or suppress the growth of Si crystal.
It was found that n, Ti, Cr, V, Mo, Zr, Zn and the like can be effectively contained.

Particularly when the mechanical and physical properties need to be improved, the improvement can be achieved by dispersing the fine particles. However, as a means for adding the dispersed particles, a molten metal containing the dispersed particles is powdered during powder production. There is a way to do that. Also, it is easy to disperse by mixing at low cost and it is effective for improving the physical property value.Moreover, when the mixed powder is further finely dispersed and uniformly and densely dispersed by mechanical pulverization and reaggregation processing, A large improvement in mechanical characteristic values can be achieved. Although these addition methods are known methods, they have found that they are effective as a method for improving the characteristics of a sintered alloy, and have completed the present invention.

That is, according to the present invention, Si is 6.0 to 40.0% by weight, Cu is 2.0 to 8.0% by weight, and Mg is 0.2 to 2.0% by weight.
Fe, Ni, Mn, if necessary.
A molten metal having a composition containing at least 8% by weight of at least one selected from Ti, Cr, V, Mo, Zr, and Zn, and a balance substantially composed of aluminum, having a solidification rate of 10 ² ° C /
After quenching the rapidly solidified aluminum alloy powder powdered for more than sec in a temperature range of 250 to 450 ° C as necessary, it is cold-compressed to a density ratio of 70% or more.
500 to 580 in non-oxidizing atmosphere below -10 ° C
Below the Al-Si eutectic temperature in the temperature range of
The present invention relates to a method for producing a sintered aluminum alloy, which is characterized in that normal pressure sintering is performed at a temperature higher than a Cu-Mg liquid phase appearance temperature and a sintered body density ratio of 90% or more.

In order to improve mechanical and physical properties, the rapidly solidified aluminum alloy powder has the above-mentioned composition and has an intermetallic compound, carbide, oxide, nitride,
A molten metal containing at least one or more particles selected from borides and silicides in an amount of 0.5 to 10% by volume has a solidification rate of 10 ² ° C / s.
It is preferably a rapidly solidified aluminum alloy powder that has been pulverized at ec or more.

Further, as a manufacturing method for improving mechanical and physical properties, a rapidly solidified aluminum alloy powder and an intermetallic compound, carbide, oxide, nitride, A step of mixing 0.5 to 10% by volume of at least one kind of particles selected from borides and silicides and, if necessary, finely and uniformly integrating the particles into the aluminum alloy powder particles by mechanical pulverization and reagglomeration. It is preferred to provide.

[0019]

The reasons for limiting the range of the composition and the manufacturing conditions will be described below.

First, a metastable phase that forms a liquid phase in a temperature range equal to or lower than the melting point can be formed when a molten metal containing Si, Cu, and Mg is solidified at a cooling rate of 10 ² ° C / sec or more. If the solidification rate is less than 10 ² ° C / sec, a metastable phase is not generated or the amount generated is small, and sintering does not proceed sufficiently.

Further, Si is an essential component for generating a liquid phase, and it is sufficient that it contains at least about 1.0% by weight. At the same time, the addition of Si lowers the coefficient of thermal expansion, improves rigidity, and reduces wear resistance. It is effective in improving the quality. This effect is obtained when the amount of Si added is 6.
0% by weight or less is small and can be easily added even by a general casting method.
% By weight. If the addition amount of Si exceeds 40.0% by weight, the melting temperature increases, the Si crystal diameter in the sintered body increases, the toughness deteriorates, and the machinability also deteriorates.
% By weight. Cu and Mg are also essential components for generating a liquid phase necessary for sintering, and the presence of Cu is particularly important. If the Cu content is less than 2.0% by weight, the amount of liquid phase required for sintering becomes insufficient, and the sintering temperature range becomes narrow. If the amount of Mg is less than 0.2% by weight, the amount of liquid phase is reduced and sufficient sintering strength cannot be obtained. Also, Cu
If the amount exceeds 8.0% by weight and the amount of Mg exceeds 2.0% by weight, the amount of generated liquid phase becomes too large and the dimensional accuracy of the sintered body deteriorates.
The strength of the base material is also deteriorated, and particularly when the amount of Mg is too large, the sintering range is narrowed. Therefore, the amount of Cu was determined to be 1.0 to 8.0% by weight, and the amount of Mg was determined to be 0.4 to 4.0% by weight. An alloy containing these components can be improved in mechanical properties by performing a solution treatment and an aging treatment.

Further, if a rapidly solidified powder is used, only a small amount can be added by the melting method in order to improve the strength of the base, improve the wear resistance by increasing the hardness of the base, and improve the heat resistance. Fe, Ni, Mn, Ti, Cr, V, M
It is possible to effectively contain o, Zr, Zn and the like. Of these components, those with a small amount of solid solution in aluminum form fine precipitates in the base material during rapid solidification, and the resulting precipitates are stable even in a relatively high temperature range and sintered. Even in the temperature range, the degree of coarsening is small and contributes to the improvement of characteristics. Further, these precipitates have a function of suppressing the coarsening of the Si crystal, and the structure of the sintered body becomes fine. Further, even in the case of solid solution molding and within the solid solution amount range, there is an effect of improving the strength by solid solution strengthening and promoting the improvement of the strength by heat treatment even when a small amount of Mn, Zn, etc. is added. The effect is manifested at a content of about the same.

However, if the amount of addition exceeds 8.0% by weight, coarse precipitates are formed during powder production, and the toughness of the sintered body is reduced.

The particle size of the powder has an optimum distribution from the viewpoints of fluidity, moldability, sinterability and the like, but is usually preferably 300 μm or less, particularly for activating the densification and reducing the quenching degree of the raw material powder. It is preferable to use a fine powder having an average particle size of about 30 μm to increase the particle size.

When the amount of Si added is about 17% by weight, when the amount of the added alloy is large, or when the degree of quenching is high, the powder hardness is high and the formability and compressibility are inferior. Annealing at ℃ improves these. If the annealing temperature is less than 250 ° C, there is no significant improvement
If the temperature exceeds ℃, the metastable phase will be stabilized by diffusion,
The annealing temperature range was 250 to 450 ° C. The holding time of the annealing is not particularly required, and the effect is sufficient if the temperature reaches the target temperature. However, in order to secure the uniformity of the treatment, it is preferable to perform heating for 30 to 60 minutes.

The powder is formed into a powder compact by cold compacting. At this time, if the compacting density ratio is less than 70%, the compact strength is reduced, so the density ratio is set to 70% or more. Molding can be warm, but is usually performed cold. Molding methods include die molding and cold isostatic pressing. In the case of mold molding, it is customary to mix a powdery lubricant or apply a lubricant to the mold in order to prevent seizure with the mold and to improve the fluidity of the powder. In particular, when high dimensional accuracy is required, it is necessary to mold at a high density of about 90 to 95%. However, since a delubricating treatment is difficult in a high-density molded article, a mold lubrication method is more preferable. However, the added lubricant needs to have a property of vaporizing in a low temperature range so as not to exert an adverse effect such as oxidation at the sintering temperature.

The compact is heated to an appropriate sintering temperature. At this time, in order to suppress the transition of the metastable phase to the stable phase, it is desirable that the rate of temperature rise to the liquid phase generation temperature range is 20 ° C./min or more. The sintering temperature is 500 to 580 ° C, which is
It is narrower in the low temperature range than 550 to 650 ° C. This is because the liquid phase formation temperature range of the Al-Si-Cu-Mg metastable phase is within this range. If the temperature is lower than 500 ° C., the sintering phenomenon does not progress because the liquid phase is not obtained. The sintering atmosphere is a non-oxidizing atmosphere such as N ₂ gas, Ar gas, vacuum, etc., in order to sufficiently remove the adsorbed water on the powder surface during the heating process and to suppress the growth of the oxide film that hinders sintering. It is necessary to sinter under a low steam partial pressure with a dew point of -10 ° C or less, preferably -30 ° C or less. The sintering time is determined by the target density of the sintered body, but when the sintering temperature is reached, sintering proceeds rapidly, so that sintering is sufficient even with heating for about 10 minutes. However, in practice, it is necessary to ensure uniformity of processing.
Heating for ~ 120 minutes will be applied. By heating for a long time, the Si crystal grows to a size effective for abrasion resistance and densification proceeds, but the strength of the sintered body deteriorates due to grain growth, so select appropriate conditions according to the required characteristic value .

The sintered body has a general cast material strength of 25 kg.
In order to secure a strength of / mm ² or more, the density ratio should be 90% or more. When the demand for high strength is strong, it is possible to manufacture a sintered body of 98% or more.
It is also possible to obtain an accuracy of about ± 10 μm by sizing or coining as%.

However, since the powder is solidified by sintering in a high temperature range, the effect of improving the strength by rapid solidification is largely impaired. In particular, when it is necessary to improve the mechanical and physical properties, fine particles are required. Can be improved. As the dispersed particles, any compound that can improve the coefficient of thermal expansion, rigidity, strength, abrasion resistance, etc. by compounding may be used.
It must not decompose, diffuse or condense during sintering. The particles selected for this purpose include some intermetallic compounds (transition metal aluminides, transition metal compounds), carbides (aluminum carbide, silicon carbide, titanium carbide, boron carbide, etc.), oxides (alumina, silica, mullite, oxide Zinc, yttria, etc.), nitride (aluminum nitride, silicon nitride, titanium nitride), boride (titanium boride), silicide (molybdenum silicide)
And so on. The size of the particles is about 0.1 to 1 μm for the purpose of strengthening the dispersion, and 1 to
About 20 μm is desirable, and about 5 to 30 μm is desirable for improving wear resistance. Of course, a plurality of types or particles having a particle size distribution can be dispersed. If the amount of dispersion is less than 0.5% by volume, the effect of adding the particles cannot be obtained, and if it exceeds 10% by volume, the machinability and toughness are poor, so the addition range is 0.5 to 10% by volume.
And

As a means for adding the dispersed particles, the mixing method is excellent in economical efficiency and is easy, and is effective in improving physical characteristic values. However, in the case of a simple mixed powder, since the dispersed particles are present only at the old powder grain boundary, it is difficult to sufficiently strengthen the dispersion, and when fine particles are dispersed, the sintering bond between the powder particles is hindered. There are aspects that are not suitable. To solve this problem, it is effective to disperse the dispersed particles in the powder particles. As the method, there are a method of pulverizing the molten metal containing the dispersed particles at the time of powder production and a method of mechanically mixing the mixed powder with the dispersed particles. There is a method of subjecting to a crushing reagglomeration treatment.

In the former method, in order to prevent segregation and agglomeration of particles, an ingot containing uniformly dispersed particles prepared in advance by a melt casting method is dissolved, or dispersed particles are added to a molten metal to induce high stirring ability. Although it needs to be dissolved, it has an excellent economic efficiency as compared with the mechanical pulverization reagglomeration treatment.

On the other hand, when the added particles are finely and uniformly integrated into the aluminum alloy powder particles by mechanical pulverization and re-agglomeration treatment, the dispersed particles having a particle diameter that contributes to the dispersion strengthening are refined to be uniform and dense. A dispersed sintered body is obtained, and a large improvement in mechanical property values is achieved. Carbides, oxides or intermetallic compounds can be produced and dispersed by mechanical pulverization and reagglomeration. This mechanical pulverization and reagglomeration treatment method is performed by a dry method instead of a wet method such as the conventional ball mill pulverization and mixing. PCA (Pr
It is also useful to add a small amount of stearic acid, alcohol, etc. as an Ocess Control Agent to prevent excessive aggregation, but this is not always necessary if the processing temperature conditions are controlled. As for the processing apparatus, a so-called attritor is suitable for high-speed processing, but is not suitable for mass processing. Ball mills require long-term treatment, but are easy to control the atmosphere, and are relatively economical if the input energy is properly designed.

The thus-obtained treated powder is such that the dispersed particles contained therein are finely pulverized and uniformly dispersed in the powder. Even when the powder is sintered, the ultrafine particles uniformly segregate the reinforcing particles. It is possible to manufacture an aluminum-based particle composite sintered alloy that has no distribution.

[0034]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 Al-24.5% by weight Si-2.4% by weight Cu-1.0% by weight M
A powder having a particle size of 5 to 300 μm was produced from a g-0.5 wt% Mn-0.4 wt% molten Fe alloy by an air atomizing method. With this powder, powders having particle sizes of about 300 μm, about 100 μm, and about 30 μm were extracted. The powder having a particle size of 300 μm was redissolved, cooled at a different solidification rate. The solidification rate was as follows: Al-3.4% by weight Cu-1.2% by weight Mg-
0.6% by weight Mn alloy powder DAS (Dendrite Arm Spaci
ng). The powder having each solidification rate was subjected to differential thermal analysis to examine the state of liquid phase generation below the melting point of the produced alloy. The heating rate was 20 ° C./min.

Table 1 summarizes the estimated solidification rate of each powder and the state of liquid phase generation. As can be seen from Table 1, the solidification rate is 10 ² ° C / s
If it is higher than ec, a liquid phase will be formed below the melting point of the alloy. A (approximately 520 ° C), B (approximately 550 ° C),
C (about 580 ° C.) is shown in FIG. However, when the temperature at the start of each phase change is determined from the differential variation point in FIG. 1, the temperature is slightly lower.

[0037]

[Table 1]

Example 2 Al-25.2% by weight Si-3.3% by weight Cu-0.6% by weight M
A powder having a particle size of 5 to 300 μm was produced from a molten alloy of g-0.4 wt% Mn-0.8 wt% Fe alloy by an air atomizing method. Add 0.4% by weight of stearic acid to this powder
It was molded into tablets of φ22 mm × 30 mm at 4 to 6 t / cm ² to produce molded articles having a density ratio of 75 ± 2%, and sintered in vacuum, N ₂ gas and air. Dew point of N ₂ gas is -35 ° C, -15
° C and + 5 ° C. Furnace temperature 500 ℃, 530 ℃,
After the temperature was raised to 560 ° C. and 590 ° C., the compact was placed in a furnace, and the heating time in the furnace was 30 minutes. Table 2 shows the density ratio of the sintered body. Under the conditions indicated by the symbol * in Table 2, 93% or more of sintered bodies were obtained. Further, under the conditions indicated by the symbol *, a sweating phenomenon occurred due to melting.

[0039]

[Table 2]

In Example 2, the roundness of each sintered body was about 30 μm, and when sizing was performed, the roundness was improved to 8 μm. Since the sintered body at 600 ° C. was completely melted in the powder grains, the Al liquid phase had flowed out to the surface layer of the sintered body. FIG. 2 (a) shows a micrograph (magnification: 100 times) of the structure of the sintered body at 575 ° C. in the atmosphere, and FIG. 2 (b), (c),
(D) is a 500 ° C sintered body in N ₂ gas (dew point -15 ° C),
Micrographs (magnification: 100 times) of the structures of the sintered bodies at 575 ° C and 600 ° C are shown respectively.

Example 3 After applying an acetone solution of stearic acid to a mold using the powder described in Example 2, a tablet of φ800 mm × 50 mm was formed at a surface pressure of 5 t / cm ² and a density ratio of 80% was obtained. A molded body was produced. The compact was sintered at a dew point of -20 ° C in N ₂ gas at a sintering temperature of 550.
As a result of sintering at 60 ° C for 60 minutes, a sintered body having a density ratio of 97% was obtained. This sintered body was subjected to a solution treatment at 510 ° C., then water-cooled, and an aging treatment at 175 ° C. for 8 hours. The tensile strength of this heat-treated body was measured, and the seizure resistance was evaluated in oil using a ring-plate sliding type seizure evaluation tester. As comparative materials, three types of heat-treated materials of a cast material having the same composition as a heat-treated material of a material obtained by sintering the same powder at 480 ° C. by extrusion and forging were prepared.

Table 3 shows the evaluation results. Although the tensile strength was lower than that of the extruded material or the forged material, the seizure load between the same materials was extremely high. 3 (a), (b),
(C) and (d) are micrographs (100 times magnification) showing the microstructure results of the sintered material, extruded material, forged material, and forged material in Example 3.

[0043]

[Table 3]

Example 4 Using a powder shown in Table 4 (maximum particle size: 75 μm), a surface pressure of 4 t / c
A tablet having a diameter of 22 mm and a size of 30 mm was molded at m ² to produce a molded body having a density ratio of 77%. The compact was sintered in N ₂ gas at a dew point of -20 ° C. The sintering temperature was 560 near the melting point to coarsen the Si crystal.
4 (a) to 4 (d) show the results of sintering at 90 ° C. for a sintering time of 90 minutes to produce a sintered body having a density ratio of 98% or more and observation of the structure. 4A is No. 1 in Table 4, and FIG. 3B is N in Table 1.
o. 2, FIG. 3 (c) is a micrograph (magnification: 100 times) showing the results of observation of the structures of No. 3 and FIG. Table 4 also shows the temperatures at points A, B, and C of the powders measured in Example 1 by differential thermal analysis. The sintered body had an oxygen content of 0.3% by weight. The tensile strength of the sintered body was 28 to 36 kg / mm ² , and No. 4 had the lowest strength.

[0045]

[Table 4]

Example 5 After the powder shown in Table 5 (maximum particle size: 350 μm) was annealed at 330 ° C. in an N ₂ atmosphere, an acetone solution of stearic acid was applied to a mold, and the surface pressure was increased. A tablet of φ22 mm × 30 mm was molded at 8 t / cm ² to produce a molded body having a density ratio of 91%. The compact was sintered at a dew point of -20 ° C in N ₂ gas at a sintering temperature of 560.
C., and sintered for 40 minutes in a sintering time to produce a sintered body having a density ratio of 95 to 97%.
(C). FIG. 5 (a) is No. 1 of Table 5, FIG.
4 (b) is a micrograph (100-fold magnification) showing the results of observation of the structures of No. 2 and No. 3 respectively. The Si crystal is refined by the addition of the transition element. When the strength of No. 1 was evaluated, a tensile strength of 40 kg / mm ² was obtained.

[0047]

[Table 5]

Example 6 Al-17.2% by weight Si-3.2% by weight Cu-1.0% by weight M
g-0.5% by weight Mn-0.4% by weight After adding 4.0% by volume of Al ₂ O ₃ particles having an average particle size of 1.8 μm and 0.9% by volume of SiC particles having an average particle size of 0.2 μm to a molten Fe alloy, Powder having a particle size of 5 to 300 μm was produced by Ar gas atomization. 0.4% by weight of stearic acid in this powder
The mixture was added and molded into a tablet of φ22 mm × 30 mm at a surface pressure of 4 t / cm ² to produce a molded body having a density ratio of 73%. Molded body has dew point
Sintered in N ₂ gas at −35 ° C. The sintering temperature was 555 ° C. and the sintering time was 60 minutes. The density ratio of the obtained sintered body was 95%. Fig. 6 shows a micrograph of the structure of the sintered body (100 times magnification).
showed that. The tensile strength after heat treatment described in Example 3 is 43 kg.
/ mm ² and the oxygen content was 0.23% by weight.

Example 7 Al-12.3% by weight Si-5.6% by weight Cu-0.4% by weight M
High energy were mixed with 2.1% by volume of an average particle size 0.1 [mu] m of B ₄ C particles in 0.99 [mu] m or less powder powder Sezo by g-0.8 wt% Mn-4.7 the air atomizing method from the weight% Fe alloy melt Mechanical re-agglomeration treatment was performed using a ball mill. This powder was annealed at 350 ° C., and then pressed at a surface pressure of 4 t / cm ² using a cold isostatic press at φ30 ×
It was molded into a 50 mm tablet with a density ratio of 81%. The compact was sintered in a N ₂ gas at a dew point of −35 ° C. The sintering temperature was 535 ° C., the sintering time was 60 minutes, and the density ratio of the sintered body was 91%.
The sintered body was subjected to coining to form a tablet having a roundness of 10 μm. FIG. 7 shows a micrograph (100-fold magnification) of the structure of the sintered body. The tensile strength after the heat treatment described in Example 3 was 41 kg / mm ² , and the oxygen amount was 1.2% by weight.

[0050]

As described above, according to the present invention, mechanical characteristics and physical characteristics are excellent with high accuracy and high density.
In addition, since an aluminum sintered alloy having excellent wear resistance can be manufactured by normal pressure sintering without using plastic working, it can be widely applied to various mechanical parts and sliding parts.

[Brief description of the drawings]

FIG. 1 is a graph showing the state of generation of a liquid phase under temperature conditions A, B, and C in Table 1.

FIG. 2 is a photomicrograph of a sintered body of Example 2.

FIG. 3 is a microstructure photograph of a sintered body of Example 3.

FIG. 4 is a microstructure photograph of a sintered body of Example 4.

FIG. 5 is a microstructure photograph of a sintered body of Example 5.

FIG. 6 is a micrograph of a sintered body of Example 6.

FIG. 7 is a microstructure photograph of a sintered body of Example 7.

Continuation of the front page (56) References JP-A-53-128512 (JP, A) JP-A-3-6344 (JP, A) JP-A-50-96409 (JP, A) JP-A-4-183959 (JP) , A) JP-A-4-308002 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 21/00-21/18 B22F 1/00-9/08 C22C 1/04 -1/10

Claims (5)

(57) [Claims] 1. Simultaneously contains 6.0 to 40.0% by weight of Si, 2.0 to 8.0% by weight of Cu, 0.2 to 2.0% by weight of Mg, and the balance is substantially aluminum. A rapidly solidified aluminum alloy powder obtained by pulverizing a molten metal having a composition consisting of at a solidification rate of 10 ² ° C / sec or more is compression-molded in a cold state to a density ratio of 70% or more, and the molded body has a dew point of -10 ° C.
500 to 580 ° C in a non-oxidizing atmosphere below
Below the Al-Si eutectic temperature in the temperature range of Al-Si-C
Atmospheric pressure sintering at a temperature higher than the u-Mg based liquid phase appearance temperature and at a sintered body density ratio of 90% or higher is characterized by a tensile strength of 25 kg /
A method for producing an aluminum sintered alloy having a thickness of ² mm or more. 2. Simultaneously contains 6.0 to 40.0% by weight of Si, 2.0 to 8.0% by weight of Cu, 0.2 to 2.0% by weight of Mg, and the balance is substantially aluminum. Having a composition consisting of, and intermetallic compounds, carbides, oxides, nitrides,
A molten metal containing 0.5 to 10% by volume of at least one kind of particles selected from borides and silicides has a solidification rate of 10%.
A rapidly solidified aluminum alloy powder powdered at ² ° C./sec or more is cold-compressed to a density ratio of 70% or more in a non-oxidizing atmosphere having a dew point of −10 ° C. or less in a non-oxidizing atmosphere. Below the Al-Si eutectic temperature, above the Al-Si-Cu-Mg liquid phase appearance temperature in the temperature range of
A method for producing an aluminum sintered alloy having a tensile strength of 25 kg / mm ² or more, characterized by normal pressure sintering to a sintered body density ratio of 90% or more. 3. A method for obtaining a rapidly solidified aluminum alloy powder.
Fe, Ni, Mn, Ti, Cr, V, M
8% by weight of at least one selected from o, Zr and Zn
3% or less.
Production method of aluminum sintered alloy. 4. A rapidly solidified aluminum alloy powder comprising 25
After annealing in a temperature range of 0 to 450 ° C., a density ratio of 7
The compression molding is performed to 0% or more.
3. Manufacture of the sintered aluminum alloy according to any one of the items 3
Method. 5. The method according to claim 1, wherein:
The tensile strength manufactured by the manufacturing method described above is 25 kg /
mm aluminum sintered alloy is ² or more.