JPH04325648A - Production of sintered aluminum alloy - Google Patents

Abstract

PURPOSE:To produce a sintered aluminum alloy having high precision and high density, excellent in mechanical properties and physical properties, and also having superior wear resistance by means of normal pressure sintering while obviating the necessity of plastic working. CONSTITUTION:A molten metal which has a composition consisting of, by weight, 6.0-40.0% Si, 2.0-8.0% Cu, 0.2-2.0% Mg, and the balance essentially aluminum and further containing, if necessary, <=8% of one or more components selected from Fe, Ni, Mn, Ti, Cr, V, Mo, Zr, and Zn is powdered at >=10<2> deg.C/sec solidification rate. The resulting rapidly solidified aluminum alloy powder is subjected, if necessary, to annealing at 250-450 deg.C and then cold-compacted to >=70% density ratio. The resulting green compact is subjected to normal pressure sintering in a nonoxidizing atmosphere with <=-10 deg.C dew point at 500-580 deg.C and also at a temp. between the Al-Si eutectic temp. and the Al-Si-Cu-Mg liquid-phase-forming temp. to >=90% density ratio.

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 an aluminum sintered alloy by pressureless sintering.

0002

[Prior Art] Since there is a strong oxide film on the surface of aluminum powder or aluminum alloy powder that cannot be reduced, in order to produce an aluminum sintered alloy,
It is necessary to break this oxide film and form a metal contact area between the powders to enable diffusion of metal atoms.

Conventionally, there have been two main methods for this.

First, in the first method, a powder having an alloy component that generates a eutectic liquid phase at a temperature lower than the melting point of aluminum or a desired aluminum alloy composition is mixed as a sintering aid, and the powder produced during compression molding is mixed as a sintering aid. In this method, a liquid phase generated from the metal contact area between the powders is generated during the heating process, covers the surface of the aluminum powder, expands the metal contact area, and progresses sintering. For example, JP-A-47-34006
No. 2, No. 2003-11-112 discloses a method for producing a sintered alloy, which is characterized by sintering a powder compact made by mixing aluminum powder with Cu or Cu-Sn powder in a non-oxidizing or reducing atmosphere. Furthermore, Japanese Patent Publication No. 51-13444 discloses a method of adding and blending powders such as magnesium and zinc as sintering aids, and JP-A No. 50-96409 discloses a method of adding and blending powders such as magnesium and zinc as sintering aids. Alternatively, a method of adding Cu-Mg master alloy powder as a sintering aid is disclosed. Similarly, Special Publication No. 61-17895, Special Publication No. 61-5485
5, Special Publication No. 61-6243 and Special Publication No. 62-66
No. 26 discloses a method of mixing elemental powders or alloy powders such as Cu, Mg, Si, and Zn.

[0005] Furthermore, as an example of adding Si,
No. 3-118209 has a eutectic composition of Al-11.
Al-Si binary alloy powder having a composition near 7Si is mixed with metallic Si powder and alloying element powder as necessary to form S.
A method for producing a sintered body containing 20 to 50% of Al in total is disclosed, and furthermore, Japanese Patent Publication No. 60-38442 discloses that Al
Or Al-Si alloy powder with Al-Cu-Mg, Al-
2, characterized in that Cu-Mg-Si, Cu-Mg-Si alloy powder is mixed as a sintering aid at a blending ratio of less than 30% by weight, and sintered at a temperature range of 550 to 650°C after compression molding. A method for manufacturing a low-density sintered body with a low Si content of .1% Si or less has been proposed. Also, JP-A-53-1285
No. 12 contains Cu, Mg in Al-10 to 35Si powder.
, a method for producing a high Si-containing sintered body is disclosed in which a Si component is added and blended as a monocomposition powder or an alloy powder. In addition, JP-A No. 3-28336 discloses that for the purpose of improving strength, Cu is added to 2.0% by weight or less and Mg is added to 0.5% by weight.
Al-10 to 45% by weight Si-Cu-Mg containing:
A mixed powder made by adding a lubricant to a system alloy powder is sintered by solid-phase diffusion below the liquid phase generation temperature, and then re-compressed. Especially when the Si content is 20% by weight, it is re-sintered after re-compression. A method for manufacturing a high-Si sintered body is presented. Cu and M
From the viewpoint of sinterability, the lower the amount of g, the better, and in the examples, each amount is 0.5% by weight or less.

Next, as a second method, there is an aluminum alloy manufacturing method that has been developed as a new powder metallurgy technology in recent years. This is a method in which the powders are subjected to strong plastic processing in order to bond them together, causing the powders to be plastically deformed and severing the oxide film on the powder surface to form metal contact areas. Plastic working methods include hot press method,
There are powder forging methods, powder extrusion methods, powder rolling methods, etc. For example, in JP-A-60-121203, aluminum alloy powder is extruded at a temperature of 250 to 550°C at an extrusion ratio of 4:1 to 15:1.
No. 1 discloses an extrusion method, and JP-A-61-1366
No. 02 discloses a method of hot pressing aluminum alloy powder after heat forming.

[0007]

[Problems to be Solved by the Invention] However, the above two conventional methods for producing aluminum sintered alloys have the following problems.

[0008] First, in the first method, a powder containing a synthetic component that generates a eutectic liquid phase that acts as a sintering aid is mixed, and the powder is sintered after compression molding. Because of the dispersion, the eutectic liquid phase is unevenly distributed, which tends to cause concentration unevenness and segregation due to the composition.The homogeneity of the sintered state of the powder is also poor, and coarse pores and outflow pores tend to remain, resulting in high precision.・Difficult to obtain high-density sintered bodies. In addition, when trying to increase the density of the compact in order to increase the number of metal contact areas and increase the frequency of eutectic liquid phase occurrence points or to improve dimensional accuracy, for example, high S
In the case of hard powders such as i-powder, high pressure is required. In addition, the sintered body obtained by this method has coarsened fine precipitates generated by rapid solidification, and its mechanical properties are significantly inferior to the sintered body obtained by the plastic working method.

In addition, Al-Si-Cu sintered by solid phase diffusion as disclosed in Japanese Patent Application Laid-Open No. 3-28336.
- The method of sintering Mg-based alloy powder can only produce a low-strength material whose strength does not reach 20 kg/mm2 because the bond between the powders is weak.

On the other hand, since sintering by the plastic working method as the second method can be processed at a relatively low temperature range, when rapidly solidified powder is used, it is possible to achieve high density while maintaining the rapid cooling effect of the powder to some extent. Although it has excellent properties because it provides a material, the equipment is expensive, manufacturing costs are high, and there are shape constraints, making it difficult to produce near net shape materials that are characteristic of conventional powder metallurgy methods, and material yields are low. low. Also,
In Al-Si alloys, the Si crystal diameter in the material is small, and wear resistance is inferior to cast materials containing the same amount of Si.

[0011] The present invention has high precision, high density, excellent mechanical properties and physical properties, and excellent wear resistance, and moreover, it is possible to obtain a near net shape material, which is an advantage of conventional powder metallurgy methods. The purpose of the present invention is to provide a method for manufacturing a high-precision aluminum sintered alloy with a high degree of freedom in shaping, which enables high-precision processing by sizing and coining if the sintered body has an appropriate amount of pores distributed. .

0012

[Means for Solving the Problems] After extensive research, the inventors have discovered that the problem with the conventional method of generating a liquid phase through a eutectic reaction and sintering is that the eutectic liquid phase can be mixed with Al powder or Al powder.
It was found that this was caused by the occurrence of sintering at the interface between the alloy powder and the sintering aid. Therefore, by inventing a method of sintering without adding or mixing any sintering aid, we attempted to solve the problems of the sintering method using the sintering aid addition method. In other words, the inventors created a liquid phase within each powder, thereby distributing the liquid phase in a highly dense and homogeneous molded body. Here, in order to generate a liquid phase in the powder, first, when powdering a molten metal containing Si, Cu, and Mg at the same time, the required alloy composition is rapidly solidified so that a liquid phase is generated below the melting point. A powder is produced in which a metastable phase is formed. By containing Si, Cu, and Mg, this alloy becomes an alloy whose strength can be improved by heat treatment.

Further research has shown that the liquid phase generated during the heating process of the powder breaks up the oxide film on the powder surface, expands the metal contact area, and progresses sintering, resulting in a homogeneous phase state within the compact. As a result, even a low-density molded body shrinks uniformly in a short period of time, and we succeeded in manufacturing a high-precision, high-density sintered body with extremely low composition unevenness and segregation. Moreover, if the powder is softened by powder annealing within a range that does not impair the formation of the liquid phase, it is possible to obtain a compact with high density at low pressure, which is effective in achieving high precision of the sintered compact, and is particularly effective for achieving high precision of sintered compacts. It was found that the effect is large when the powder hardness is high in the system.

Further, according to the above-mentioned rapid solidification method, in order to harden the base material, improve heat resistance, or suppress the growth of Si crystals, Fe, Ni, and Mn, which can only be added in small amounts in the melting method, are added.
, Ti, Cr, V, Mo, Zr, Zn, etc., can be effectively contained therein.

In particular, when mechanical and physical properties need to be improved, they can be improved by dispersing fine particles, but as a means of adding dispersed particles, it is possible to powder a molten metal containing dispersed particles during powder production. There is a way to do it. In addition, dispersion by mixing is low cost and easy, and is effective in improving physical properties.Furthermore, if the mixed powder is mechanically crushed and reagglomerated, the dispersed particles can be made finer and dispersed uniformly and densely. Great improvements in mechanical property values can be achieved. These methods of addition are known methods, but the present invention has been completed based on the discovery that they are effective methods for improving the properties of sintered alloys.

[0016] That is, in this invention, Si is 6.0 to 40
．． 0% by weight, 2.0 to 8.0% by weight of Cu, 0.2 to 2.0% by weight of Mg, and further contains Fe, Ni, Mn, Ti, Cr, V, Mo, Zr
, rapidly solidified aluminum alloy powder obtained by pulverizing a molten metal having a composition of 8% by weight or less of one or more selected components from Zn and the remainder substantially consisting of aluminum at a solidification rate of 102° C./sec or more. 250 if necessary
After annealing in the temperature range of ~450 °C, the density ratio is 7 in the cold.
0% or higher, and the molded body is compressed to a dew point of -10°C.
500 to 580 in a non-oxidizing atmosphere of
Below the Al-Si system eutectic temperature in the temperature range of °C, Al-Si
-Cu-Mg system liquid phase appearance temperature or higher, sintered compact density ratio 90%
The present invention relates to a method for producing an aluminum sintered alloy characterized by pressureless sintering.

Further, in order to improve the mechanical and physical properties, the rapidly solidified aluminum alloy powder has the above composition and contains intermetallic compounds, carbides, oxides, nitrides,
A molten metal to which 0.5 to 10% by volume of at least one particle selected from borides and silicides has been added has a solidification rate of 1.
Preferably, the aluminum alloy powder is rapidly solidified aluminum alloy powder that has been pulverized at a temperature of 0.02° C./sec or higher.

Furthermore, as a manufacturing method for improving mechanical and physical properties, between the process of rapidly solidifying powder production and compression molding, rapidly solidified aluminum alloy powder is mixed with intermetallic compounds, carbides, oxides, nitrides, 0.5 to 10% by volume of at least one particle selected from borides and silicides
It is preferable to provide a step of mixing and finely and uniformly integrating the aluminum alloy powder particles into the aluminum alloy powder particles by mechanical crushing and reagglomeration treatment if necessary.

[0019]

[Operation] The reason for limiting the range of composition and manufacturing conditions will be explained below.

First, a metastable phase that forms a liquid phase in a temperature range below the melting point can be formed when a molten metal containing Si, Cu, and Mg at the same time is solidified at a cooling rate of 102° C./sec or higher. This is because if the solidification rate is less than 102° C./sec, the metastable phase will not be produced or the amount of metastable phase produced will be small, and sintering will not proceed sufficiently.

[0021] Furthermore, Si is an essential component for liquid phase generation, and it is sufficient to contain it at least about 1.0% by weight. Effective in improving wear resistance, etc. This effect is small when the amount of Si added is 6.0% by weight or less, and since this is an amount that can be easily added using a general casting method, the lower limit of Si addition is set to 6.0% by weight in the present invention. If the amount of Si added exceeds 40.0% by weight, the melting temperature will increase, the Si crystal diameter in the sintered body will increase, the toughness will deteriorate, and the machinability will also deteriorate.
The upper limit of addition amount was set to 40.0% by weight. Cu and Mg are also essential components for producing a liquid phase necessary for sintering, and the presence of Cu is particularly important. 2.0 in Cu amount
If it is less than % by weight, the amount of liquid phase required for sintering will be insufficient and the sintering temperature range will be narrow. Also 0 in Mg amount
．． If it is less than 2% by weight, not only will the amount of liquid phase decrease, but also sufficient sintering strength will not be obtained. In addition, the amount of Cu is 8.0% by weight, M
If the amount of Mg exceeds 2.0% by weight, the amount of liquid phase generated will be too large, resulting in poor dimensional accuracy of the sintered body and deterioration of the strength of the substrate.In particular, if the amount of Mg is too large, the sintering range will be reduced. Make it narrower. Therefore, the amount of Cu is 1.0 to 8.0% by weight, Mg
The amount was determined to be 0.4 to 4.0% by weight. The mechanical properties of alloys containing these components can be improved by subjecting them to solution treatment and aging treatment.

[0022] Furthermore, if rapidly solidified powder is used, it is possible to improve the strength of the base material, increase the hardness of the base material to improve wear resistance, and improve heat resistance by adding only a small amount in the melting method. Fe, Ni, Mn, Ti, Cr, V, Mo
, Zr, Zn, etc. can be effectively contained. Among these components, those with a small amount of solid solution in aluminum form fine precipitates in the matrix during rapid solidification, and the resulting precipitates are stable even in a relatively high temperature range and are difficult to sinter. Even in the temperature range, the degree of coarsening is small and contributes to improved characteristics. Furthermore, these precipitates have the function of suppressing coarsening of the Si crystals, resulting in a finer structure of the sintered body. Also,
Even with solid solution molding or within the solid solution amount range, strength improvement due to solid solution strengthening, and addition of small amounts of Mn, Zn, etc., have the effect of promoting strength improvement through heat treatment.
The effect of Mn etc. is exhibited at a content of about 0.5% by weight.

However, if the amount added exceeds 8.0% by weight, coarse precipitates are formed during powder production and the toughness of the sintered body is reduced, so this is set as the upper limit.

[0024] The particle size of the powder has an optimum distribution from the viewpoint of fluidity, moldability, sinterability, etc., but it is usually 300 μm or less. In order to increase the particle size, it is recommended to use fine powder with an average particle size of about 30 μm.

[0025] When the amount of Si added is around 17% by weight, when the amount of added alloy is large, or when the degree of quenching is high, the powder hardness is high and the formability and compressibility are poor. These are improved by annealing at ℃. If the annealing temperature is less than 250 °C, there will be no significant improvement effect, and if it exceeds 450 °C, the metastable phase will be stabilized by diffusion, so the annealing temperature range is 250 to 450 °C.
℃. The holding time for annealing is not particularly necessary, and the effect is sufficient as long as the target temperature is reached, but in order to ensure uniformity of the process, it is preferable to heat for 30 to 60 minutes.

[0026] The powder is formed into a powder compact by cold compaction, but at this time, the compact density ratio is set to be 70% or more, since the strength of the compact will be low if the compaction density ratio is less than 70%. Although molding can be done warm, it is usually done cold. Molding methods include die molding and cold isostatic pressing. In the case of mold molding, it is customary to mix a powdered lubricant or apply a lubricant to the mold in order to prevent sticking with the mold and improve the fluidity of the powder. When particularly high dimensional accuracy is required, it is necessary to mold to a high density of about 90 to 95%, but since it is difficult to remove lubricant with a high-density molded product, a mold lubrication method is more preferable. However, the added lubricant must have the property of vaporizing in a low temperature range so as not to cause adverse effects such as oxidation at the sintering temperature.

[0027] The compact is heated to an appropriate sintering temperature. At this time, in order to suppress the transition from the metastable phase to the stable phase, it is desirable that the temperature increase rate to the liquid phase generation temperature range be 20° C./min or more. The sintering temperature is 500 to 580°C, which is a lower temperature range and narrower than the conventional sintering temperature range of 550 to 650°C. This is because the liquid phase formation temperature range of the metastable phase of the Al-Si-Cu-Mg system is within this range. If the temperature is lower than 500°C, the sintering phenomenon will not proceed because it will not become a liquid phase, and if the temperature exceeds 580°C, the alloy itself will melt, the structure will become coarse, and the precision will deteriorate significantly. The sintering atmosphere is
In order to sufficiently remove adsorbed moisture on the powder surface during the temperature raising process and suppress the growth of an oxide film that impedes sintering, the dew point should be - - in a non-oxidizing atmosphere such as N2 gas, Ar gas, or vacuum 1
It is necessary to sinter at a low water vapor partial pressure of 0°C or lower, preferably -30°C or lower. The sintering time is determined by the target density of the sintered body, but since sintering proceeds quickly once the sintering temperature is reached, sufficient sintering can be achieved even with heating for about 10 minutes. However, in reality, it is 30 to 120 because of the need to ensure uniformity of processing.
It will be heated for several minutes. By heating on the long-term side, S
Although the i-crystals grow to a size effective for wear resistance and densification progresses, the strength of the sintered body deteriorates due to grain growth, so appropriate conditions are selected depending on the required characteristic values.

The sintered body has a strength of 25, which is a general casting material strength.
90% density ratio to ensure strength of kg/mm2 or more
The above shall apply. If there is a strong demand for high strength, it is possible to manufacture a sintered body with a density of 98% or more, and if there is a strong demand for high precision, the density ratio can be set to 95-97% and an accuracy of about ±10 μm can be obtained by sizing or coining. It is possible.

However, since the powder is solidified by sintering in a high temperature range, the strength improvement effect of rapid solidification is largely lost. This can be improved by dispersing the Dispersed particles may be any particles that can improve thermal expansion coefficient, rigidity, strength, abrasion resistance, etc. by compounding.
It must not decompose, diffuse, or condensate during sintering. The particles selected for this purpose are some intermetallic compounds (transition metal aluminides, transition metal intermetallic compounds), carbides (aluminum carbide, silicon carbide, titanium carbide, boron carbide, etc.), oxides (alumina, silica, mullite, oxidized zinc, yttria, etc.), nitrides (aluminum nitride, silicon nitride, titanium nitride), borides (titanium boride), silicides (molybdenum silicide)
etc. The particle size is approximately 0.1 to 1 μm when aiming for dispersion reinforcement, approximately 1 to 20 μm when aiming for a composite effect, and 5 to 30 μm for improving wear resistance.
degree is desirable. Of course, it is also possible to disperse particles having multiple types and particle size distributions. Dispersion amount is 0.5
If the amount is less than 1% by volume, the effect of adding particles cannot be obtained, and 1
Since machinability and toughness will be poor if the content exceeds 0% by volume, the addition range is set to 0.5 to 10% by volume.

As a means for adding dispersed particles, a mixing method is economical and easy, and is effective in improving physical property values. However, in the case of a simple mixed powder, the dispersed particles exist only at the grain boundaries of the old powder, so it is difficult to achieve sufficient dispersion strengthening, and when fine particles are dispersed, the sintering bond between the powder particles is inhibited. There are some aspects that are not appropriate. An effective way to solve this problem is to disperse dispersed particles within the powder particles.There are two methods for this: pulverizing molten metal containing dispersed particles during powder manufacturing, and machine-processing a mixed powder to which dispersed particles have been added. There is a method of pulverizing and re-agglomerating.

In the former method, in order to prevent segregation and agglomeration of particles, an ingot uniformly containing dispersed particles prepared in advance by melting and casting is melted, or dispersed particles are added to the molten metal to induce high stirring ability. Although it requires melting, it has superior economic efficiency compared to mechanical crushing and reagglomeration treatment.

On the other hand, when the additive particles are finely and uniformly integrated into the aluminum alloy powder particles by mechanical crushing and reagglomeration treatment, the dispersed particles having a particle size that contributes to dispersion strengthening are made fine and uniform and dense. A dispersed sintered body is obtained and the mechanical properties are greatly improved. Carbides, oxides, or intermetallic compounds can also be produced and dispersed by mechanical crushing and reagglomeration. This mechanical crushing and reagglomeration treatment method is carried out in a dry manner rather than in a conventional wet manner such as ball milling or mixing. In some cases, PCA (P
It is also useful to prevent excessive aggregation by adding a small amount of stearic acid, alcohol, etc. as a process control agent, but this is not always necessary if the processing temperature conditions are controlled. Further, as for the processing device, a so-called attritor is suitable for high-speed processing, but is not suitable for large-volume processing. Ball mills require long processing times, but the atmosphere can be easily controlled, and if the input energy is properly designed, it is relatively economical.

In the thus obtained treated powder, the contained dispersed particles are finely pulverized and uniformly dispersed in the powder, and even when the powder is sintered, the extremely fine reinforcing particles are segregated uniformly. It becomes possible to produce an aluminum base particle composite sintered alloy with evenly distributed aluminum base particles.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples 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 wt%Mg-0.5 wt%Mn-0.4 wt%
The particle size is 5 ~ by air atomization method from Fe alloy molten metal.
A 300 μm powder was produced. From this powder, powders having particle sizes of about 300 μm, about 100 μm, and about 30 μm were taken out. The powder with a particle size of 300 μm was remelted and cooled by changing the solidification rate. The solidification rate was as follows: Al-3.4 wt% Cu-1.2 wt% Mg-0 prepared by the same method
．． 6 wt% Mn alloy powder DAS (Dendrite)
Arm Spacing). The state of liquid phase generation below the melting point of the produced alloy was investigated by differential thermal analysis of powders with various solidification rates. The temperature increase rate was 20°C/min.

Table 1 summarizes the estimated solidification rate and liquid phase generation status of each powder. As can be seen from Table 1, the solidification rate is 102
C/sec or more, a liquid phase is generated below the merging point. A (approximately 520 °C) and B (in the liquid phase generation situation in Table 1)
(approximately 550°C) and C (approximately 580°C) are shown in Figure 1, respectively. However, if the temperature at which each phase change starts is determined from the differential variation point in FIG. 1, it will be slightly on the lower temperature side.

[0037]

[Table 1]

Example 2 Al-25.2% by weight Si-3.3% by weight Cu-0.
6 wt%Mg-0.4 wt%Mn-0.8 wt%
The particle size is 5 ~ by air atomization method from Fe alloy molten metal.
A 300 μm powder was produced. 0.4% by weight of stearic acid was added to this powder, and it was molded into a φ22mm x 30mm tablet at a surface pressure of 4 to 6t/cm2 until the density ratio was 7.
A 5±2% compact was prepared and sintered in vacuum, N2 gas, and air. The dew point of N2 gas is -35℃
, -15°C, and +5°C. The temperature inside the furnace is 50
The molded body was placed in a furnace after being heated to 0°C, 530°C, 560°C, and 590°C, and the heating time in the furnace was 30 minutes. Table 2 shows the density ratio of the sintered bodies. Under the conditions indicated by the symbol * in Table 2, a sintered body of 93% or more was obtained. In addition, under the conditions indicated by the symbol *, a sweating phenomenon occurred due to melting.

[0039]

[Table 2]

In this Example 2, the roundness of each sintered body was about 30 μm, and when sizing was carried out, the roundness improved to 8 μm. The sintered body at 600°C was completely melted within the powder grains, so that the Al liquid phase flowed out onto the surface layer of the sintered body. Figure 2(a) shows a micrograph (100x magnification) of the structure of the sintered body at 575°C in the atmosphere.
b), (c), and (d) in N2 gas (dew point -15 °C)
) 500 °C sintered body, 575 °C sintered body and 60 °C sintered body
Micrograph of the structure of the sintered body at 0°C (100x magnification)
are shown respectively.

Example 3 After applying an acetone solution of stearic acid to a mold using the powder described in Example 2, it was molded to a diameter of 800 m with a surface pressure of 5 t/cm2.
m x 50mm tablets with a density ratio of 80%
A molded body was produced. The molded body was exposed to N2 at a dew point of -20°C.
As a result of sintering in gas at a sintering temperature of 550° C. for a sintering time of 60 minutes, a sintered body with a density ratio of 97% was obtained. This sintered body was solution-treated at 510 °C, then water-cooled, and
Aging treatment was performed at 75°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. Three types of comparison materials were prepared: a heat-treated material made by extruding the same powder and sintering it by forging at 480° C., and a heat-treated material made from a cast material having the same composition.

The evaluation results are shown in Table 3, and although the tensile strength was not as high as that of extruded materials or forged materials, the seizure load between the same materials was extremely high. Figure 3(a),(b),(
c) and (d) are micrographs (100 times enlarged) showing the structure results of the sintered material, extruded material, forged material, and forged material in Example 3.

[0043]

[Table 3]

Example 4 Using the powder shown in Table 4 (maximum particle size: 75 μm), a surface pressure of 4
A tablet with a diameter of 22 mm x 30 mm was molded at t/cm2 to produce a molded product with a density ratio of 77%. The dew point of the molded body is -
The sintering temperature was 560 °C, near the melting point, in order to coarsen the Si crystals in N2 gas at 20 °C, and the sintering time was 90 minutes to produce a sintered body with a density ratio of 98% or more, and the structure was observed. The results are shown in FIGS. 4(a) to 4(d). Figure 4(a) is Table 4
No. 1, Figure 3(b) is No. 1 in Table 1. 2, Figure 3 (
c) is No. 3, Figure 3(d) is No. Micrographs (100x magnification) showing the results of each tissue observation in 4.
It is. In addition, Table 4 also lists the temperatures at points A, B, and C based on the differential thermal analysis of each powder measured in Example 1. Further, the amount of oxygen in the sintered body was 0.3% by weight. The tensile strength of the sintered body is 28 to 36 kg/mm2, and No. 4
had the lowest intensity.

[0045]

[Table 4]

Example 5 After annealing the powder shown in Table 5 (maximum particle size: 350 μm) at 330°C in an N2 atmosphere, an acetone solution of stearic acid was applied to a mold, and a surface pressure of 8t was applied. /cm2
A tablet with a diameter of 22 mm x 30 mm was molded to produce a molded product having a density ratio of 91%. The molded body is heated to a dew point of -20°C.
The sintering temperature was set to 560 °C in N2 gas, and the sintering time was 40 minutes to produce a sintered body with a density ratio of 95 to 97%. The results of microstructural observation are shown in Figures 5(a) to 5(a). Shown in (c). FIG. 5(a) shows No. 5 in Table 5. 1, FIG. 4(b) is No.
2. Figure 4(c) is No. 3 is a micrograph (100 times magnification) showing the results of tissue observation for each of No. 3. The Si crystal becomes finer due to the addition of the transition element. No. 1
When the strength was evaluated, the tensile strength was 40 kg/mm.
2 was obtained.

[0047]

[Table 5]

Example 6 Al-17.2% by weight Si-3.2% by weight Cu-1.
0 wt%Mg-0.5 wt%Mn-0.4 wt%
Al2 with an average particle size of 1.8 μm is contained in the Fe alloy molten metal.
The O3 particles were 4.0% by volume and the average particle size was 0.2μ.
After adding 0.9% by volume of SiC particles of 500 µm, a powder having a particle size of 5 to 300 µm was produced by Ar gas atomization. Add 0.4% by weight of stearic acid to this powder.
φ22mm x 30mm with a surface pressure of 4t/cm2
A molded product with a density ratio of 73% was produced. The compacts were sintered in N2 gas with a dew point of -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 (100 times enlarged) of the structure of the sintered body. The tensile strength after the heat treatment described in Example 3 was 43 kg/mm2, and the oxygen content was 0.23% by weight.

Example 7 Al-12.3% by weight Si-5.6% by weight Cu-0.
4 Weight%Mg-0.8 Weight%Mn-4.7 Weight%
B with an average particle size of 0.1 μm is added to the powder of 150 μm or less, which is stored by air atomization from molten Fe alloy.
After 2.1% by volume of 4C particles were mixed, mechanical crushing and reagglomeration treatment was performed using a high-energy ball mill. After annealing this powder at 350°C, it was molded into φ30×50 pieces using a cold isostatic press at a surface pressure of 4t/cm2.
It was molded into a tablet with a density ratio of 81%. The compacts were sintered in N2 gas with 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 coined into a tablet with a roundness of 10 μm. Figure 7 shows a micrograph of the structure of the sintered body (10
(0x magnification). The tensile strength after the heat treatment described in Example 3 was 41 kg/mm2, and the oxygen content was 1.2% by weight.

[0050]

[Effects of the Invention] As explained above, according to the present invention, an aluminum sintered alloy with high precision, high density, excellent mechanical properties and physical properties, and excellent wear resistance can be produced by plastic working. First, it can be manufactured by pressureless sintering.
It can be widely applied to various mechanical parts and sliding parts.

[Brief explanation of drawings]

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

FIG. 2 is a photograph of the microscopic structure of the sintered body of Example 2.

FIG. 3 is a photograph of the microscopic structure of the sintered body of Example 3.

FIG. 4 is a photograph of the microscopic structure of the sintered body of Example 4.

FIG. 5 is a photograph of the microscopic structure of the sintered body of Example 5.

FIG. 6 is a photograph of the microscopic structure of the sintered body of Example 6.

FIG. 7 is a photograph of the microscopic structure of the sintered body of Example 7.

Claims (3)

[Claims] Claim 1: 6.0 to 40.0% by weight of Si, C
u from 2.0 to 8.0% by weight, Mg from 0.2 to 2.0% by weight.
0% by weight, and further contains Fe, N as necessary.
A molten metal containing 8 wt. Rapidly solidified aluminum alloy powder powdered at a temperature of ℃/sec or more is annealed at a temperature range of 250 to 450℃ as necessary, and then cold compression molded to a density ratio of 70% or more. In a non-oxidizing atmosphere of 10°C or less, in the temperature range of 500 to 580°C, below the Al-Si eutectic temperature, above the Al-Si-Cu-Mg liquid phase appearance temperature, and sintered body density ratio of 90% or more A method for producing an aluminum sintered alloy having a tensile strength of 25 kg/mm2 or more, the method comprising pressureless sintering. 2. The rapidly solidified aluminum alloy powder according to claim 1 contains 6.0 to 40.0% by weight of Si, 2.0 to 8.0% by weight of Cu, and 0.2 to 2.0% of Mg.
% by weight, and further contains Fe, Ni,
Contains 8% by weight or less of one or more components selected from Mn, Ti, Cr, V, Mo, Zr, and Zn, with the remainder consisting essentially of aluminum, and contains intermetallic compounds and carbides. , 0.5 to 10% by volume of at least one particle selected from oxides, nitrides, borides, and silicides.
A method for producing an aluminum sintered alloy having a tensile strength of 25 kg/mm2 or more, characterized in that the added molten metal is pulverized at a solidification rate of 102 °C/sec or more to produce rapidly solidified aluminum alloy powder. 3. In the manufacturing method according to claim 1, between the steps of rapidly solidifying powder production and compression molding, rapidly solidifying aluminum alloy powder and intermetallic compounds, carbides, oxides, nitrides, borides, and silicides are added. It is characterized by providing a step of mixing 0.5 to 10% by volume of at least one selected type of particles and finely and uniformly integrating them into the aluminum alloy powder particles by mechanical crushing and re-agglomeration treatment if necessary. A method for producing an aluminum sintered alloy having a tensile strength of 25 kg/mm2 or more.