JPH0657363A - Nitrogen compound aluminum sintered alloy and method for producing the same - Google Patents

Abstract

(57) [Summary] [Purpose] High precision, high density, mechanical properties, physical properties,
And an aluminum sintered alloy having excellent wear resistance, and a method for producing the alloy with high economic efficiency by pressureless sintering without plastic working. [Structure] A rapidly solidified aluminum alloy powder obtained by solidifying an aluminum alloy melt containing 0.4 to 4.0% by weight of Mg at a solidification rate of 10 ² ° C / sec or more is added as necessary.
After annealing in a temperature range of 0 to 450 ° C., cold compression molding is performed, and this compact is added with a reducing gas component of 0.01 atm or more as a nitrogen compounding promoting gas component and a nitrogen partial pressure of 0.8 atm.
In a normal pressure atmosphere having a steam partial pressure of 0.01 atm or less, a compound with nitrogen is produced on the powder surface and sintered, 0.4 to 4.0 wt% of Mg and 0.2 to 0.2% of nitrogen are contained.
A nitrogen compounded aluminum sintered alloy containing 4.0% by weight is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aluminum sintered alloy having high precision, high density, excellent mechanical properties and physical properties, and excellent wear resistance, and an aluminum sintered alloy which is not subjected to plastic working but under normal pressure. The present invention relates to a method of producing by sintering with high economy. The present invention provides an aluminum alloy satisfying the properties required for machine structural parts by a pressureless sintering method capable of imparting a shape with a high degree of freedom, and its fields of use include side plates of compressor parts, housings, and cylinders. , A case, a vane, a shoe, a rotor, etc., a timing pulley of an automobile part, an oil pump rotor, a bush, etc., or a roller, a gear, a bearing, etc. of an office equipment.

[0002]

2. Description of the Related Art A strong oxide film that cannot be reduced exists on the surface of aluminum powder or aluminum alloy powder. Therefore, in order to produce a sintered aluminum alloy, this oxide film is broken and metal contact between the powder particles occurs. It is necessary to form a portion to enable diffusion of metal atoms. This is because a strong sintered body cannot be obtained unless the powder is firmly bonded by the diffusion of metal atoms. Conventionally, this method is roughly divided into the following two methods.

Method of Mixing Sintering Aid A powder having an alloying component that generates a eutectic liquid phase at a temperature lower than the melting point of aluminum or aluminum alloy composition is added as a sintering aid to a raw material, compression-molded, and fired. The eutectic liquid phase is generated from the metal contact portion between the sintering aid and the aluminum powder or aluminum alloy powder formed in the compact during the temperature rising process of the binding process, thereby expanding the metal contact portion and sintering. It is a method of proceeding. JP-A-47-3400
No. 6 proposes a method for producing an aluminum (Al) sintered alloy in which a powder compact obtained by mixing aluminum powder with Cu or Cu—Sn powder is sintered in a non-oxidizing or reducing atmosphere. Japanese Examined Patent Publication No. 51-13444 is M as a sintering aid.
A method of adding powders such as g and Zn has been proposed. Japanese Unexamined Patent Publication No. 50-96409 proposes a method of adding Mg powder or Cu—Mg master alloy powder as a sintering aid. Japanese Patent Publication 61-17895, Japanese Patent Publication 61
-54855, Japanese Patent Publication 61-6243, Japanese Patent Publication 62-6
626 discloses a method of mixing elemental powders such as Cu, Mg, Si and Zn or alloy powders as a sintering aid.

A method of manufacturing a sintered alloy containing Si will be described below. In JP-B-53-118209, Al-Si binary alloy powder having a composition near Al-11.7Si which is a eutectic composition is mixed with metal Si powder as a sintering aid and alloy powder as required, and Si is added. Has been proposed for producing a sintered body containing 20 to 50% in total. Japanese Patent Sho 60-384
42 is Al powder or Al-Si alloy powder.
Cu-Mg, Al-Cu-Mg-Si, Cu-Mg-S
i alloy powder was mixed at a compounding ratio of less than 30 wt% as a sintering aid, compression molded, and then sintered in a temperature range of 550 to 650 ° C.,
A method for producing a low Si content low density sintered body of 2.1% Si or less is proposed. Japanese Examined Japanese Patent Publication 59-37339 is Al-1
There has been proposed a method for producing a high Si-containing sintered body in which Cu, Mg, and Si components are added as a single composition powder or an alloy powder in 0 to 35 Si powder. In addition, Mg
Al-25Si-2Cu-0.5 containing a small amount of components
An example in which Mg alloy powder is sintered in a high-purity nitrogen gas (dew point −70 ° C. or lower) atmosphere at 555 ° C. for 60 minutes is described, but the tensile strength of the sintered body is only 9.2 kg / mm ^2. Not not.

Method of applying plastic working A method developed in recent years as a new powder metallurgical technique, which is a method of joining powders by plastic deformation. By subjecting the powder to strong plastic working, the powder is plastically deformed, the oxide film on the surface of the powder is broken and divided, and adjacent powders are connected to form a metal contact portion. Since the oxide film is broken by a physical method, the sintering aid is unnecessary. As the plastic working method, a hot pressing method, a powder forging method, a powder extrusion method, a powder rolling method and the like are used. Since the method by plastic working can be processed in a relatively low temperature range, a high-density alloy can be obtained in which the effect of rapid solidification is maintained to some extent. JP 60-1
21203 is aluminum alloy powder having a temperature of 250 to 5
A method of extruding at 50 ° C. with an extrusion ratio of 4: 1 to 15: 1 is proposed. Since the aluminum alloy powder is extruded with a strong shearing force, the oxide film on the powder surface is broken and the metal inside the adjacent powder particles is bonded. JP 61-136
602 proposes a method of hot pressing aluminum alloy powder after hot molding. By hot pressing,
This is to break the oxide film on the powder surface and bring the internal metals into contact with each other to diffuse metal atoms.

As described above, both of the method of mixing the sintering aid and the method of plastic working can break the oxide film and realize the contact between the metals, and the metal atoms can diffuse through the contact portion.

[0007]

However, each of the two conventional methods for producing the aluminum sintered alloy described above has the following drawbacks. Difficulties of the method using a sintering aid In the method of sintering the powder mixed with the sintering aid powder that generates a eutectic liquid phase after compression molding, the sintering aid is dispersed by the mixing method. There is a problem that the liquid phase is unevenly distributed. Therefore, in terms of composition, density unevenness and segregation are likely to occur, and the homogeneity of the sintered state of the powder is poor. It is difficult to obtain high-precision and high-density sintered compacts because coarse pores and outflow holes are likely to remain. Further, in the sintered body obtained by this method, fine precipitates generated by rapid solidification are coarsened, and the mechanical properties are significantly inferior to those of the sintered body produced by the plastic working method. Difficulties of the plastic working method Sintering by the plastic working method has an advantage that a high density material can be obtained because it can be processed in a relatively low temperature range. However, since high pressure must be applied for processing, the equipment is expensive and the manufacturing cost is high. Further, there are shape restrictions, and it is difficult to manufacture a near net shape material, which is a feature of conventional powder metallurgy, and the material yield is low.

The conventional method using a sintering aid for generating and sintering a liquid phase by a eutectic reaction has problems of uneven distribution of the eutectic liquid phase, uneven concentration, segregation, etc. Sintered alloy cannot be obtained. This produces a eutectic liquid phase at the interface between the Al powder or Al alloy powder and the sintering aid,
This is due to the fact that the oxide film is divided and then sintered.
Since the distribution of the sintering aid is non-uniform, the distribution of the eutectic liquid phase is not uniform, resulting in uneven concentration and segregation. Therefore, the first object of the present invention is to produce an Al sintered alloy without using a sintering aid. Further, if plastic working is used, the facility cost and manufacturing cost increase as described above. Therefore, the second object of the present invention is to produce an Al sintered alloy without using plastic working.

[0009]

The nitrogen compounded aluminum sintered alloy of the present invention is characterized by containing 0.4 to 4.0% by weight of Mg and 0.2 to 4.0% by weight of nitrogen. Nitrogen compound aluminum sintered alloy. In addition, the manufacturing method is, if necessary, a rapidly solidified aluminum alloy powder obtained by solidifying an aluminum alloy melt containing 0.4 to 4.0% by weight of Mg at a solidification rate of 10 ² ° C / sec or more in an amount of 250 to 4
After annealing in a temperature range of 50 ° C., cold compression molding is performed, and the compact is added with a reducing gas component of 0.01 atm or more as a nitrogen compounding promoting gas component, a nitrogen partial pressure of 0.8 atm or more and a steam partial pressure of 0. It is characterized in that a compound with nitrogen is produced on the powder surface and sintered under an atmospheric pressure of 0.01 atm or less.

Briefly, the aluminum sintered alloy of the present invention is obtained by forming an aluminum alloy powder containing Mg and accelerating the sintering by a nitrogen compounding reaction with a nitrogen component in a sintering atmosphere gas to form a powder composition. It is an alloy that has been sintered with high precision at atmospheric pressure below its melting point without plastic working. The normal pressure means that the pressure applied to the molded body during sintering is a normal pressure by the atmospheric gas, and an extremely high pressure such as the above-mentioned plastic working is not used.

By combining the powder surface modification by adding Mg and the compounding reaction with atmospheric nitrogen, it has become possible to accelerate the sintering phenomenon of the aluminum alloy powder, which has been conventionally difficult. The physical and mechanical properties of
Since the density of the sintered body is largely controlled, the second point in the production of the sintered alloy is how dense a sintered alloy can be produced. As the densification method, the following two methods using a rapidly solidified alloy powder were found.

Method for increasing the density during molding It is effective to increase the density during molding in order to obtain a highly accurate and high-density sintered body. Molding methods include die molding and cold isostatic pressing. In the case of die molding, in order to prevent seizure with the die and to improve the fluidity of the powder, a powdery lubricant is mixed or the lubricant is directly applied to the die. Generally, increasing the molding pressure enables high-density molding. However, since the load on the mold is increased and the molding shape is restricted, and the life of the mold is shortened, high-pressure molding exceeding ⁸ to 10 t / cm ² is not usually adopted. Therefore, in order to obtain a high compaction density during compaction, it is necessary to use a raw material powder having excellent compressibility and compactibility. The compacting density is influenced by the powder shape and the like, but is largely controlled by the powder hardness. It is important that the powder matrix is soft in order to densify during molding. From the viewpoint of hardness, it is desirable that the matrix composition is a low alloy. However, in order to ensure practical strength, an aging precipitation hardening type element is added to the composition so that the characteristics can be improved by heat treatment. Therefore, the powder is overaged to be softened. It is effective to disperse hard particles in a matrix in order to secure physical properties, mechanical properties or wear resistance. The hard particles are preferably hard particles such as ceramics that do not form a solid solution in the matrix or Si crystals having a small solid solubility so as not to deteriorate the moldability of the powder. Hard particles or Si crystals can be finely and homogeneously dispersed by rapidly cooling and solidifying by melting a molten metal in which hard particles are dispersed or Si is melted, and even if a large amount of particles or Si is contained, Bridging can be suppressed and the effect on high density can be reduced. In addition, soft powder can be mixed in a part to improve the formability and compressibility and to increase the strength of the sintered body.

Method of densifying at the time of sintering For applications requiring heat resistance, thermal stability or high mechanical properties, a high alloy matrix in which a hard and stable intermetallic compound is dispersed is required. According to the rapid solidification method, Fe, Ni, Mn, or T, which can be added only in a small amount in the melting method, in order to harden the substrate and improve heat resistance.
It is possible to effectively contain i, Cr, V, Mo, Zr and the like. However, although the matrix hardness is high and the formability and compressibility are somewhat improved by powder annealing,
Since it is difficult to increase the density by only molding, a manufacturing method for densifying during sintering is required. Generally, when a liquid phase is generated during sintering, it becomes dense, but there is a large amount of liquid phase,
If the distribution of the generated liquid phase is inhomogeneous, the dimensional accuracy will deteriorate. In addition, the generation of a large amount of liquid phase also leads to coarsening of the structure. As a liquid phase sintering method, there is a method of generating a liquid phase by a conventional eutectic reaction and sintering, but the problem of this method is that the eutectic liquid phase is formed of Al powder or Al alloy powder and a sintering aid. This is due to the fact that the sintering is performed at the interface. Therefore, the problem of the sintering method by the addition method of the sintering aid is solved by the method of sintering without adding and mixing the sintering aid at all. That is, by uniformly producing a small amount of liquid phase in each powder, the liquid phase is uniformly distributed in the compact to realize uniform shrinkage during sintering and obtain high dimensional accuracy. In the present invention, in order to generate a liquid phase in the powder, first, Cu,
At the time of pulverizing a molten metal having a composition containing Mg at the same time, it is rapidly solidified to form a powder in which a metastable phase is formed so that a liquid phase is formed at a melting point of a required alloy composition or less. The metastable liquid phase generated during the heating step of the powder divides the oxide film on the surface of the powder to expand the metal contact portion, and the sintering proceeds. Since the phase state in the compact is uniform, even a small amount of liquid phase shrinks uniformly in a short time, and it is possible to manufacture a high-precision and high-density sintered body with minimal composition unevenness and segregation. Also in this case, if the powder is softened by the powder annealing within the range where the generation of the liquid phase is not impaired, a high-density molded body can be obtained at a low pressure, which is effective in improving the accuracy of the sintered body. Further, by mixing a part of the soft powder, the molding density can be increased and the sinterability can be improved. Since this alloy contains Cu and Mg, the strength can be improved by heat treatment. In the method of densifying during sintering, if further improvement of mechanical and physical properties is required, it can be improved by dispersing fine particles. As a means for adding dispersed particles, it is easy to disperse them by a mixing method, but there is a problem such as particle agglomeration, and the effect of improving mechanical properties cannot be obtained. Therefore, in the present invention, a method of powderizing a molten metal containing dispersed particles at the time of powder production or a method of mechanically pulverizing and re-aggregating a mixed powder to finely disperse the dispersed particles and disperse the dispersed particles uniformly and at high density Improve the characteristic value.

The sintered material obtained by the method of the present invention can be used as a near net shape material, which is an advantage of the conventional powder metallurgy method. If a sintered body having an appropriate amount of pores is distributed, sizing and sizing can be performed. It can be said that this is a method for producing a high-precision sintered body that enables high-precision processing by coining and has a high degree of freedom in shape giving.

[0015]

In the present invention, the composition and manufacturing conditions are limited. The meaning of these limitations is explained below.

[Amount of Mg Added] In the present invention, the addition of Mg is important. Mg has the function of reducing the oxide film formed on the powder surface during spraying at the time of sintering and, at the same time, promoting the reaction with atmospheric nitrogen and expanding the metal contact portion to promote the sintering phenomenon. When coexisting with Si or Cu, mechanical properties can be improved by performing solution treatment and aging treatment. If the addition amount of Mg is 0.4% by weight or less, the above effect becomes insufficient. On the other hand, if it exceeds 4.0% by weight, the dimensional accuracy of the sintered body deteriorates, and the heat resistance and toughness of the base material deteriorate. Therefore, the desirable Mg content is 0.4 to 4.
It is 0% by weight.

[Nitrogen Content] In the present invention, the nitrogen content is particularly important. Nitrogen is present as a nitrogen compound generated on the surface of the powder during the sintering by the reaction between atmospheric nitrogen and the aluminum alloy, and accelerates the sintering phenomenon. Further, since the nitrogen compound is hard, the wear resistance is improved. Nitrogen content is 0.2
If the content is less than or equal to wt%, the above effects will be insufficient.
On the contrary, if a nitrogen compound amount exceeding 4.0% by weight is present, the toughness of the sintered body is lowered. Therefore, the desirable nitrogen content is 0.2 to 4.0% by weight.

[Form of Nitrogen Compound] The compounding reaction between the raw material powder and nitrogen takes place on the surface of the powder, and the nitrogen compound is generated at the interface of the old powder or on the surface of the old powder. Let Further, unlike the case where the nitrogen compound is dispersed as particles, the nitrogen compound of the present invention is excellent in adhesiveness because it is generated by the reaction, and is extremely densely dispersed, which greatly improves wear resistance and hardness. .
However, if the nitrogen compound layer exceeds 10 μm, the toughness is reduced, so the thickness is set to 10 μm or less. Under normal sintering conditions, the thickness of the nitrogen compound is 0.1-5 μm.
It is a degree.

[Solidification Rate of Spray Powder] In the present invention, the solidification rate of the molten aluminum alloy during the production of the spray powder is important. In the method of liquefying the metastable phase at the time of sintering and performing the liquid phase sintering, it is essential that the metastable phase is generated in the raw material powder, and the metastable phase is generated by rapid solidification. If the solidification rate is less than 10 ² ° C / sec, a metastable phase will not be formed, or even if it is formed, the amount will be small and sintering will not proceed sufficiently. Further, in the method of increasing the density during molding, it is effective to accumulate diffusion energy during sintering by rapid solidification in order to accelerate the sintering phenomenon. Coagulation rate is 1
If it is less than 0 ² ° C / sec, the above effect becomes insufficient, so that the desirable solidification rate is 10 ² ° C / sec or more.

[Powder Particle Size] When the powder is produced by the spraying method, the solidification rate varies depending on the particle size of the powder. In addition, the frequency of metal contact between powders and the surface area that reacts with nitrogen are also greatly affected by the particle size of the powder. If the maximum particle size of the powder exceeds 350 μm or if the average particle size exceeds 75 μm, the sinterability decreases. Therefore, the maximum particle size is 3
It is desirable that the average particle size is 50 μm or less and the average particle size is 75 μm or less.

[Granulation of powder] When the particle size of the sprayed powder is small, the fluidity and the filling property of the powder into the mold are not good. Therefore, by mechanically granulating the sprayed powder, it is possible to improve the accuracy of the sintered body as a powder having excellent fluidity and filling properties while sufficiently maintaining the quenching degree and the physical properties of the powder.

[Powder Annealing] When it is necessary to improve the formability and compressibility, the powder may be annealed. Since the sprayed powder has been rapidly solidified, is in a so-called quenched state and has high hardness, it softens when annealed at an aging temperature of the alloy or higher, so that formability and compressibility can be improved. Annealing is 2
If the temperature is lower than 50 ° C, it takes a long time to soften the powder due to overaging, and if the temperature exceeds 450 ° C, the powders are sintered with each other or the sintering energy accumulated by rapid solidification is consumed. , There is a problem that the metastable phase is stabilized. Therefore, annealing is 250 to 450 ° C.
Done in. Within this temperature range, if the powder is heated to the annealing temperature at a normal heating rate, the pure powder is softened, but in the case of annealing with high homogeneity, the holding time of the annealing is at least 30.
~ 60 minutes required.

[Cold Forming] It is possible to perform warm forming for high-density forming, but in the case of the present invention, cold forming is sufficient in view of economical efficiency and its effect.

[Lubricant] In the case of die molding, it is usual to mix powdered lubricant with the raw material powder or to apply lubricant directly to the die in order to prevent seizure with the die. is there.
The lubricant to be added needs to be one that vaporizes at a temperature lower than the sintering temperature and does not impair the sinterability.

[In the case of low hardness powder] Mixing of powder having a hardness lower than that of the raw material powder can improve moldability and compressibility. The Mg content of the low hardness powder to be mixed is set to 0.4 to 4.0% by weight for the reason described above. In order to ensure the softness of the powder, the Al component needs to be 85% by weight or more. Other components can be contained as long as the hardness is lower than that of the main raw material powder. Mixing amount of low hardness powder is 3
It is 0% by weight or less. If it exceeds this, a portion where the added low hardness powders sinter is produced, and the strength improving effect is reduced. Therefore, the amount is 30% by weight or less.

[Molded product density ratio] In the method of increasing the density during molding, if the molded product density ratio is less than 90%, the strength of the sintered product becomes low. To avoid this, the density ratio is 90%
It is desirable to set it as above. In order to obtain a sintered body having excellent strength and toughness, it is preferable that the molding density be high. Further, in the liquid phase sintering method in which the density is increased during sintering, it is difficult to obtain a high compaction density because the powder is hard, but the strength of the compact decreases when the compact density ratio is less than 70%. . therefore,
The density ratio is 70% or more.

[Sintering atmosphere] In the present invention, the sintering atmosphere is particularly important. It is necessary to form an atmosphere mainly composed of nitrogen gas in order to generate a nitrogen compound on the surface of the powder at the time of sintering to promote the sintering phenomenon and improve the wear resistance of the sintered material. For that purpose, the nitrogen partial pressure needs to be 0.8 atm or more. At the same time, a reducing gas component is added as 0.01 as a gas component that promotes nitrogenation on the powder surface.
Must be added at least atm. Atmospheric pressure is
Pressurization can promote some sintering, but atmospheric pressure is sufficient from the viewpoint of economy and equipment. Further, if the water vapor partial pressure in the atmosphere is high, the Mg component, which functions to reduce the oxide film on the powder surface during sintering and at the same time to promote the reaction with atmospheric nitrogen, reacts with the water vapor, and the effect of adding the Mg component Inhibit. Further, the water vapor also has a function of decomposing the nitrogen compound formed on the powder surface. In addition, the water vapor partial pressure must be lowered in order to evaporate and decompose the moisture adsorbed on the powder in the process of raising the temperature to the sintering temperature. Therefore, it is important to keep the water vapor partial pressure below 0.01 atm.

[Sintering temperature] The molded body is heated to an appropriate temperature and sintered. The sintering temperature differs between the alloy system in the case of the manufacturing method in which the density is increased during molding and the alloy system in the case of the manufacturing method in which the density is increased during sintering. In the former case, the sintering temperature range is preferably 500 to 570 ° C. If it is less than 500 ° C., the reaction amount with atmospheric nitrogen is poor, and the sintering phenomenon due to solid phase diffusion does not proceed sufficiently. Conversely, if the temperature exceeds 570 ° C, Al
When the eutectic point of —Si approaches 578 ° C., the alloy is softened and deformed, the precision is significantly deteriorated, and the structure is coarsened. The sintering temperature is set to 500 to 570 ° C. in order to sufficiently advance the sintering, ensure the accuracy, and suppress the coarsening of the structure. When higher accuracy is required, 520 to 550 ° C is desirable. On the other hand, in the latter case, the sintering temperature is higher than the liquidus generation temperature Tc of the metastable phase obtained by the rapid solidification method, and the temperature is lower than the melting point Tm of the powder. Of course, the liquid phase generation temperature Tc and the melting point Tm of the metastable phase differ depending on the alloy composition of the powder. In the alloy system of the present invention, the liquidus generation temperature of the metastable phase is around 500 ° C., and the melting point of the powder is around 580 ° C.

[Sintering time] The molded body is heated and sintered in a sintering temperature range for an appropriate time. Sintering time 20-30
The sintering proceeds even in minutes. However, in practice, it is desirable to perform heating for 1 to 4 hours in order to ensure the uniformity of sintering and higher strength. As the sintering time increases, the reaction amount with nitrogen in the atmosphere also increases, the sintering phenomenon progresses, and the morphology and size of the precipitates effective for improving wear resistance change while densifying. Therefore, the sintering time must be selected according to the required characteristics and dimensional accuracy. Further, in the manufacturing method of densifying at the time of sintering, since a liquid phase is generated at the time of sintering, the progress of sintering is fast, and the manufacturing method of densifying at the time of molding can be performed in a considerably short time.

[Dimensional Change During Sintering] In the alloy system of the manufacturing method in which the density is increased during forming, it is possible to suppress the dimensional change during sintering and perform high-precision sintering. The dimensional change rate for ensuring this dimensional accuracy is within 1.5%. If higher dimensional accuracy is required, it is desirable to be within 1%.

[Sintered Body Density Ratio] The higher the sintered body density ratio, the better the Young's modulus and mechanical properties of the sintered body. With a sintered alloy system that densifies during molding, tensile strength of 25 kg / mm ²
Sintered alloy system that densifies during sintering and has a tensile strength of 30 kg / mm ²
In order to secure the above, the density ratio of the sintered body needs to be 90% or more. When higher mechanical properties and the like are required, it is possible to manufacture a sintered body having a density ratio of 97% or more. Further, when the density ratio is about 94 to 96%, good sizing and coining are possible, and a highly accurate product can be obtained. Further, if the pores in the sintered body are impregnated with oil, lubricity can be provided. In order to have such an effect, the upper limit of the sintering density ratio is set to 99%.

[Alloy composition when densifying at the time of forming]
The requirement for the raw material powder in the manufacturing method of densifying at the time of molding is that the matrix before molding is soft. Therefore, it is necessary to limit the alloy components as follows. Mg
The component is an essential component in the present invention, but if the annealing treatment is applied in the range of 0.4 to 4.0% by weight described above,
It does not significantly impair the moldability and compressibility of the powder. However, in order to improve the wear resistance and the heat resistance by increasing the strength of the matrix and the hardness of the matrix, C
When u, Mn, Fe, Ni and the like are contained, if the total amount of addition exceeds 2.0 wt%, the compressibility at the time of molding deteriorates, so the upper limit of these total amounts is 2 wt%. Further, as an additional element that improves the characteristics of the material without impairing the moldability and compressibility, the inventors have found a Si component that has a small amount of solid solution in the matrix and exhibits a particle-dispersed structure. The addition of Si is effective in lowering the coefficient of thermal expansion, improving rigidity, improving wear resistance and the like. Since this effect is small when the Si addition amount is 4.0 wt% or less, the lower addition amount is set to 4.0 wt% in the present invention. Si
If the addition amount exceeds 40.0 wt%, adverse effects on formability and compressibility cannot be ignored, and the Si crystal size in the sintered body becomes large, the toughness deteriorates and machinability deteriorates. The limiting amount was 40.0 wt%. Since the alloy system contains Si and Mg, heat treatment is possible.

[Alloy composition when densifying during sintering]
The addition of Cu necessary for forming the metastable phase is indispensable for the alloy composition in the manufacturing method in which the metastable phase is liquefied during sintering to increase the density. If the addition amount of Cu is small, a metastable phase is not formed, or even if it is formed, the liquid phase amount required for densification cannot be obtained. If the amount of Cu added is large, the amount of liquid phase becomes large and the dimensional accuracy becomes poor. Therefore, the amount of Cu added to generate a necessary amount of the metastable phase is 1.0 to 8.0% by weight. This system alloy contains Mg at the same time and can be subjected to age hardening heat treatment. In the sintering method for achieving densification by liquid phase sintering, it is possible to use a hard powder which is less required to have a high density during molding and is excellent in wear resistance and heat resistance. Cu is an essential component for forming a metastable phase and hardens the matrix. Further, at the same time, there are transition elements such as Fe, Ni, Mn, etc. as the components excellent in the characteristic improving effect. Fe, Ni,
The addition of the transition element of Mn is effective in lowering the coefficient of thermal expansion, improving rigidity, improving wear resistance and the like. Conventional forging methods can only add small amounts of these transition elements. According to the rapid solidification method used in the present invention, it can be added at a high concentration, and hard and fine crystallized substances / precipitates are formed during rapid solidification, and the seizure resistance and strength of the alloy are greatly improved. Further, these crystallized substances / precipitates are relatively thermally stable and effective in improving heat resistance, and the degree of coarsening is small even in the sintering temperature range. This effect is small when the total content (Ni + Fe + Mn) is 5.0 wt% or less, so 5.0 wt% or more is desirable. On the other hand, if the amount of (Ni + Fe + Mn) exceeds 30.0 wt%, the melting temperature becomes high and it becomes difficult to make it into a molten metal, and the precipitates in the sintered body become large and the toughness deteriorates and machinability also deteriorates. Not desirable. Therefore, (Fe + N
The amount of i + Mn) added is preferably 5.0 to 30.0 wt%.
Further, when it is necessary to improve mechanical / physical properties, addition of Si or Ti, Cr, V, Mo, Zr, etc. is effective. In particular, the effect of adding Si is effective in reducing the coefficient of thermal expansion, improving rigidity, improving wear resistance, etc., as described above. However, in the case of liquid phase sintering, since the Si crystal becomes coarse and the toughness decreases, the amount that can be added becomes smaller than in the sintering method in which the density is increased during molding. The present inventor discloses a sintering method of an Al-high Si alloy utilizing the liquefaction phenomenon of the metastable phase in Japanese Patent Application No. 3-124846. In this case, however, since the amount of Si added is large, the material There was a problem in applications requiring toughness and reliability. Therefore, in the present invention, it is possible to maintain toughness and improve thermal expansion and wear resistance by adding a transition element, and the upper limit of the amount of Si added is 8.0% by weight, which does not significantly deteriorate toughness. In addition, Ti, Cr,
The components of V, Mo and Zr are expensive and the addition amount is 8.0.
Since the toughness is deteriorated when the content exceeds 10% by weight, the upper limit of addition is set to 8.0% by weight. In the present invention, these elements may not be contained.

[Dispersion of Hard Particles] Especially when improvement of mechanical and physical properties is required, it is possible to improve by dispersion of fine particles. As the dispersed particles, any particles that can improve the thermal expansion coefficient, rigidity, strength, wear resistance and the like by forming a composite may be used, and it is desirable that the dispersed particles do not disperse or diffuse or grow by sintering. The particles selected for this purpose are intermetallic compounds, carbides, oxides, nitrides, borides, silicides and the like. I will give an example. Intermetallic compounds / transition metal aluminides, transition intermetallic compounds Carbides: aluminum carbide, silicon carbide, titanium carbide, boron carbide, etc. Oxides: alumina, silica, mullite, zinc oxide, yttria, etc. Nitride: aluminum Nitride, silicon nitride, titanium nitride, etc. Boride: titanium boride, etc. Silicide: molybdenum silicide, etc.

[Particle Size of Dispersed Particles] Particle size is also an important factor. This also depends on the main purpose. For the purpose of strengthening dispersion: 0.1 to 1 μm Dispersion has a function of stopping the movement of transition. In this case, a fine particle size of 0.1 to 1 μm is desirable. In the case of aiming at a composite effect: 1 to 20 μm This is to secure the degree of bonding at the matrix interface of the composite particles and increase the volume ratio. For the purpose of improving wear resistance: 5 to 30 μm Disperse relatively coarse particles of 5 to 30 μm so that the particles do not fall off by sliding. These particles may be added alone or in plural kinds.

[Amount of dispersed particles] The amount of dispersed particles is 0.5.
If it is less than the volume%, the effect of adding particles does not appear. On the other hand, if it exceeds 30% by weight, machinability and toughness are poor. Therefore, the amount of dispersed particles is preferably 0.5 to 30% by weight.

[Means for Adding Dispersed Particles] As a means for adding dispersed particles, a mixing method in which these dispersed particles are mixed with the raw material powder is economical and easy, and is effective in improving physical property values. However, in the simple mixing method, the dispersed particles exist only in the old powder grain boundaries and the particles cannot be dispersed in the powder, and it is difficult to sufficiently improve the characteristics by dispersing the particles. Further, when fine particles are dispersed, it hinders the sintering bond between the powder particles and is not suitable. To solve this problem, it is effective to disperse it in powder particles, and there are the following two methods. A method of pulverizing a molten metal containing dispersed particles during powder production. This is a method in which a molten metal containing particles is pulverized by a rapid solidification method. Since the particles are added before pulverization, the particles are dispersed inside the powder. In order to prevent the particles from segregating or agglomerating, it is necessary to use an ingot produced by a melt casting method and which contains dispersed particles uniformly, or to add the dispersed particles to a molten metal to induce induction melting with a high stirring ability. Method of mechanically pulverizing and reaggregating mixed powder to which dispersed particles are added This is a method of adding particles to rapidly solidified powder and mechanically pulverizing and reaggregating. By this mechanical pulverization reaggregation treatment, the added particles can be finely and uniformly integrated into the aluminum alloy powder. It is also possible to generate and disperse carbides, oxides or intermetallic compounds during the treatment by mechanical pulverization reaggregation treatment. This treatment is performed by a dry method instead of a conventional wet method such as ball milling and mixing. In some cases, excessive aggregation may be prevented by adding a small amount of stearic acid or alcohol as a PCA (Process Control Agent). Attritor is suitable for high-speed processing. On the other hand, the ball mill requires a long treatment time, but the atmosphere control is easy, and it is relatively economical if the input energy is properly designed.
Dispersed particles contained in the treated powder thus obtained were finely pulverized and uniformly dispersed in the powder, and by firing the powder, aluminum-based particles in which fine particles were uniformly dispersed without segregation A composite sintered alloy can be manufactured.

[Sizing / Coining] Since the sintered body has pores inside, sizing and coining are possible, and surface roughness and dimensional accuracy can be greatly improved. It is also possible to process sizing and coining with a heat-treated body.

[0039]

【Example】

<Example 1> The maximum particle size produced by the air atomizing method is 300 μm or less, and the average particle size is 35 μm.
Two kinds of powders shown in (1) were prepared.

[0040]

[Table 1]

After the powder was annealed at 400 ° C., an acetone solution of myristic acid was applied to a mold and molded into a test piece of 10 × 10 × 55 mm at a molding pressure of 7 t / cm ² .
The molded body was sintered at 540 ° C. for 4 hours in the following three kinds of normal pressure atmospheres containing 0.005 atm of a nitrogen compound promoting component gas. (a) Nitrogen partial pressure 0.99 atm or more, steam partial pressure 0.005a
Atmospheric pressure below tm (b) Argon partial pressure 0.99 atm or more, steam partial pressure 0.0
Atmospheric pressure atmosphere of 05 atm or less (c) Nitrogen partial pressure 0.90 atm or more, steam partial pressure 0.05 atm
In the above atmospheric pressure atmosphere, the sintered body is subjected to solution treatment at the same temperature as the sintering temperature, and then 17
Aging treatment was performed at 0 ° C. Table 2 shows the dimensional change rate and characteristic values during sintering.

[0042]

[Table 2]

It can be seen that a sintered alloy having excellent properties can be obtained by sintering while combining with nitrogen in a nitrogen atmosphere in which the partial pressure of water vapor is suppressed. FIG. 1 shows a structure of a nitrogen compound which can be observed in a sintered body having a powder composition and a scanning electron microscope.

Example 2 Two kinds of powders, shown in Table 3 below, having a maximum particle size of 300 μm or less and an average particle size of 42 μm manufactured by the air atomization method were prepared.

[0045]

[Table 3]

After the powder is annealed at 300 ° C., an acetone solution of myristic acid is applied to the mold and the compact density is in the range of 93.0-93.5% at a compacting pressure of 7 t / cm ^2. Thus, a test piece of 10 × 10 × 55 mm was molded.
The compact was sintered and water-cooled at 560 ° C. for 0.5 to 4 hours in a normal pressure atmosphere containing a reducing gas of 0.004 atm and a nitrogen partial pressure of 0.99 atm or more and a steam partial pressure of 0.003 atm or less. Table 4 shows the characteristic values of the sintered body. FIG. 2 shows the microstructure of the sintered body that was sintered for 4 hours.

[0047]

[Table 4]

Due to the inclusion of Mg, S exceeds the old powder grain boundary.
It can be observed that i is diffused and Ostwald grown, and the sinterability is remarkably improved, and it can be seen that excellent sintered body characteristics are obtained.

Example 3 The following three types of Al having a particle size of 5 to 149 μm produced by the air atomizing method are described below.
-Si-based alloy powder was prepared. Al-9.0Si-1.4Mg-0.5Cu-0.3
Mn-0.5Fe alloy powder Al-16.6Si-1.5Mg-0.5Cu-0.
4Mn-0.6Fe alloy powder Al-24.8Si-1.8Mg-0.4Cu-0.
3Mn-0.7Fe alloy powder This powder was annealed at 400 ° C., 1 wt% of powdery lubricant was added, and the mixed powder was granulated into a size of 20 to 400 μm by a mechanical granulator. The granulated powder was molded using a hydraulic 200t press into a side plate shape with a pressing area of 26 cm ² as shown in FIG. 6 so that the molding density was 90 to 94%. The compact was sintered in a furnace in which a reducing gas of 0.002 atm was added and N ₂ gas having a water vapor partial pressure of 0.003 atm or less was introduced. The temperature in the furnace was 540 ° C., and the heating time in the furnace was 2 Hr. The sintered body was water-cooled after sintering and was subjected to an aging treatment at 170 ° C. × 8 Hr. Table 5 shows the dimensional change rate and characteristics during sintering. FIG. 3 shows microstructure photographs of the heat-treated body and the heat-treated material of the cast A390 alloy. As a comparative material, the characteristics of the Al2 powder + Si powder + Mg powder were mixed to prepare a mixed powder corresponding to the composition and manufactured under the same manufacturing conditions, and the characteristics of the cast ADC12 material are also shown.

[0050]

[Table 5]

It can be seen that according to the method of the present invention, a product having a complicated shape such as a side plate can be economically manufactured with high precision using an aluminum sintered alloy having a low thermal expansion and excellent characteristics.

Example 4 Four kinds of Al-Fe-Ni shown in Table 6 below produced by the air atomizing method
-Mn-based alloy powder was prepared.

[0053]

[Table 6]

Then, the powder classified to a powder of 105 μm or less was annealed at 400 ° C., and a mixed powder containing 1 wt% of a powdery lubricant was added to a test piece of 10 × 10 × 55 mm at a surface pressure of 6 to 8 t / cm ^2. Was molded into a molded body having a density ratio of 82 to 88%.
The compact was sintered in a belt furnace in which a reducing gas of 0.002 atm was added and N ₂ gas having a water vapor partial pressure of 0.003 atm or less was introduced. The furnace temperature was 540 ° C., and the heating time in the furnace was 1 hr. The sintered body was water-cooled after sintering and was subjected to an aging treatment at 170 ° C. × 8 Hr. Table 7 shows the characteristics of the sintered body. FIG. 4 shows the microstructure of the sintered body.
When sizing was performed on each sintered body, the maximum surface roughness was improved to 3 μm and the dimensional accuracy was improved to 10 μm. As a comparative material, an alloy having a composition corresponding to 149 to 3 having a slow solidification rate was used.
Sintered alloy manufactured under the same conditions using 50 μm powder, and Al-4.4Ni-5.5Fe-0.4Mn powder with C
The heat-treated material characteristics of a sintered alloy produced under the same conditions using a mixed powder containing 4 wt% of u powder and 2.5 wt% of Mg powder, and a cast alloy produced by the casting method are shown.

[0055]

[Table 7]

When a powder having a fast solidification rate is used, densification proceeds due to liquefaction of the metastabilized phase, and an alloy having excellent properties which cannot be produced by the casting method can be produced. No generation of a liquid phase was found even when the cutting powder of the sintered body of the present invention was heated, and it can be seen that the metastabilized phase has all transitioned to the stabilized phase.

Example 5 In a melting furnace in which two types of metal shown in Table 8 are melted, 2.0% by volume of Al ₂ O ₃ particles having an average particle diameter of 4 μm and SiC having an average particle diameter of 9 μm are used. 1 particle
After adding 0% by volume, a particle-dispersed composite powder having an average particle size of about 40 μm was manufactured by the air atomization method.

[0058]

[Table 8]

After the powder was annealed at 400 ° C., an acetone solution of stearic acid was applied to a mold and molded into a test piece of 10 × 10 × 55 mm at a molding pressure of 7 to 8 t / cm ² . The compact was sintered for 2 hours at 550 ° C. in a normal pressure atmosphere containing a reducing gas of 0.002 atm and a nitrogen partial pressure of 0.99 atm or more and a water vapor partial pressure of 0.005 atm or less, and then heat-treated. Table 9 shows the characteristic values of the heat-treated body.

[0060]

[Table 9]

It can be seen that the physical and mechanical properties are improved by the dispersion of the particles.

Example 6 Two kinds of powders, shown in Table 10 below, having a maximum particle size of 300 μm or less and an average particle size of 35 μm manufactured by the air atomization method were prepared.

[0063]

[Table 10]

This powder was mixed with 2% by volume of yttria particles having an average particle size of 1.2 μm, and then mechanically pulverized and reaggregated using a high energy ball mill. This powder is annealed at 420 ° C., and then an acetone solution of stearic acid is applied to the die, and the surface pressure is set to 30 × 4 at a surface pressure of 11 t / cm ^2.
Molded into 0 mm tablets. The compact was sintered and heat-treated at 540 ° C. for 4 hours in a normal pressure atmosphere containing a reducing gas of 0.02 atm and a nitrogen partial pressure of 0.99 atm or more and a steam partial pressure of 0.005 atm or less. The sintered body was subjected to coining to give a tablet having a roundness of 10 μm. Table 11
The characteristic values of the heat-treated body are shown in FIG.

[0065]

[Table 11]

It can be seen that the dispersion of the particles improves the physical and mechanical properties.

Example 7 Two kinds of powders, shown in Table 12 below, having a maximum particle size of 300 μm or less and an average particle size of 35 μm manufactured by the air atomizing method were prepared.

[0068]

[Table 12]

After this powder was annealed at 350 ° C., 2024
(Al-4.1Cu-1.4Mg-0.4Mn-0.3
Si) alloy powder is added in an amount of 10 and 20% by weight, and further 1
A powder lubricant of weight% was added and mixed in a V blender. The mixed powder was molded into a test piece of 10 × 10 × 55 mm with a surface pressure of 7 t / cm ² . The molded product has a nitrogen partial pressure of 0.99 atm or more with a reducing gas added of 0.04 atm and a steam partial pressure of 0.005 atm.
After sintering at 550 ° C. for 2 hours in the following atmospheric pressure atmosphere,
Heat treatment was applied. Table 13 shows the characteristic values of the heat-treated body. FIG. 5 shows microstructure photographs of the heat-treated body obtained by mixing 1024% by weight of 2024 powder with the powder sintered at 540 ° C. and the heat-treated body obtained by mixing 10% by weight of 2024 powder with the powder.

[0070]

[Table 13]

It can be seen that the mechanical properties are improved by the mixed addition of the soft powder.

Example 8 Using the powder evaluated in Example 2, a sintered material and a powder forged material were produced. The sintering conditions were the same as in Example 2 except that the sintering time was 4 hours.

For the test, a thrust type friction tester in which a ring-shaped test piece and a plate-shaped test piece were slid in a wet manner was used.
The plate material was a heat-treated material of A390 (Al-17Si alloy) material. Sliding area is 1.2 cm ² and sliding speed is 4 m /
With a constant second, the load is 5 kgf per minute for step-up type
The pressure was gradually increased to 500 kgf, but if seizure occurred before reaching the final load, the tester stopped and the load was taken as the seizure load. Table 14 shows the results of the test. Compared with the sintered material of the present invention and the powder forged material, Si crystals or hard precipitates in an appropriate form effective for wear resistance are uniformly dispersed, and excellent resistance to wear is obtained. Has wear characteristics. In particular, the sintered material has a matrix structure exceeding Hmv200 and is excellent in wear resistance.

[0074]

[Table 14]

Example 9 Al-5.5Mn-3.4Ni-1.4Fe-3.n having a maximum particle size of 105 μm or less and an average particle size of 38 μm manufactured by the air atomization method.
7Cu-2.2Mg alloy powder was prepared. 4 this powder
After annealing at 00 ° C., 0.7 wt% of powder lubricant was mixed and molded into a test piece of 40 × 16 × 5 mm at a molding pressure of 7 t / cm ² . The molding was carried out by sintering at 540 ° C. for 2 hours in a normal pressure atmosphere containing a reducing gas of 0.003 atm and a nitrogen partial pressure of 0.99 atm or more and a water vapor partial pressure of 0.04 atm or less, followed by heat treatment. Both sides of the heat-treated body were ground and then polished to form a sliding vane for a rotary compressor of 38.8 × 15.6 × 4.4 mm.

The maximum particle size produced by the air atomization method is 149 μm or less, and the average particle size is 42 μm.
1-16.6Si-1.5Mg-0.5Cu-0.3M
An n-0.6Fe alloy powder was prepared. 400 this powder
After annealing at a temperature of 1 ° C., 1 wt% of a powder lubricant was mixed and molded at a molding pressure of 6 t / cm ² into a rotor shape having an outer diameter of 59.5 mm and four vane grooves each having a width of 3.8 mm. The molding was carried out by sintering at 540 ° C. for 4 hours in the same atmospheric pressure atmosphere as the vane material, followed by heat treatment. As for the heat-treated body, after turning the end face, the vane groove was polished and processed into a compressor rotor.

Next, when the main sinter rotor and the main sinter vane were combined and operated at 300 rpm for 4800 rpm, the wear amount of both the rotor material and the vane material was 5 μm or less, which was at a practical level. In addition, vibration and noise generated during rotation are 20% compared to iron-based compressors of the same design.
The above was also reduced and the efficiency was improved by 8%. Furthermore, when the vane material was treated with Ni-P plating and operated at the same rotation speed, no decrease in efficiency was observed even after the operation for 1000 hours.

[0078]

EFFECTS OF THE INVENTION According to the present invention, an aluminum sintered alloy having high precision and high density, excellent mechanical properties and physical properties, and excellent wear resistance can be formed with a high degree of freedom without plastic working. It can be manufactured by the atmospheric pressure sintering method, and is used for compressor parts such as side plates, housings, cylinders, cases, vanes, shoes, and rotors, timing pulleys for automobile parts, oil pump rotors, bushes, and rollers for office equipment. It can be widely applied to various mechanical parts such as gears, bearings, and sliding parts.

[Brief description of drawings]

FIG. 1 is a structure of a nitrogen compound observable in a sintered body having a powder composition and a scanning electron microscope according to Example 1 of the present invention.

FIG. 2 is a microstructure of a powder composition and a sintered body of Example 2 of the present invention.

FIG. 3 is a microscopic structure of a powder composition, a sintered body, and a heat-treated cast A390 alloy in Example 3 of the present invention.

FIG. 4 is a powder composition in Example 4 of the present invention;
Microscopic structure of the sintered body.

FIG. 5 shows a powder composition and a microstructure of a sintered body in Example 7 of the present invention.

FIG. 6 is a perspective view showing a side plate shaped molded body according to a third embodiment of the present invention.

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[Procedure amendment]

[Submission date] May 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a scanning electron microscope of nitrogen compounds that can be observed in a sintered body having a powder composition and a composition according to Example 1 of the present invention.
A photograph of the metallographic structure .

FIG. 2 is a photomicrograph of a metallographic structure of a sintered body having a powder composition and a sintered body according to Example 2 of the present invention.

FIG. 3 is a microscopic metal set of a powder composition, a sintered body, and a cast A390 alloy heat-treated body in Example 3 of the present invention.
Woven photos .

FIG. 4 is a powder composition in Example 4 of the present invention;
A photograph of the metallographic structure of the sintered body under a microscope.

FIG. 5 is a microscopic photograph of a metal structure of a powder composition and a sintered body in Example 7 of the present invention.

FIG. 6 is a perspective view showing a side plate shaped molded body according to a third embodiment of the present invention.

Claims (12)

[Claims] 1. A nitrogen compounded aluminum sintered alloy containing 0.4 to 4.0% by weight of Mg and 0.2 to 4.0% by weight of nitrogen. 2. The nitrogen compound is formed on the old powder interface or on the old powder surface, and the thickness of the nitrogen compound layer is 10 μm.
The nitrogen compounded aluminum sintered alloy according to claim 1, wherein: 3. A rapidly solidified aluminum alloy powder obtained by solidifying an aluminum alloy melt containing 0.4 to 4.0% by weight of Mg at a solidification rate of 10 ² ° C./sec or more at a temperature of 250 to 450 ° C. as required. After annealing in the zone, cold compression molding was performed, and this compact was added with a reducing gas component of 0.01 atm or more as a nitrogen compounding promoting gas component.
1. A method for producing a nitrogen compounded aluminum sintered alloy, which comprises producing a compound of nitrogen on the powder surface and sintering it under an atmospheric pressure atmosphere of atm or more and water vapor partial pressure of 0.01 atm or less. 4. The method for manufacturing an aluminum sintered alloy according to claim 3, wherein the atomized powder has a maximum particle size of 35.
The method for producing an aluminum sintered alloy according to claim 3, wherein the dimensional accuracy is high, which is 0 μm or less and an average particle size is 75 μm or less. 5. The method for producing an aluminum sintered alloy according to claim 3 or 4, wherein the spray powder is subjected to mechanical granulation treatment, and the dimensional accuracy is high.
Alternatively, the method for producing an aluminum sintered alloy according to claim 4. 6. The method for producing an aluminum sintered alloy according to claim 3, wherein the compact has a density ratio of 90.
% Or more, the sintered body is sintered to a density ratio of 90% or more and 99% or less in the range of 500 to 570 ° C., the dimensional change rate during sintering is 1.5% or less, and the sintered body has a tensile strength. The method for producing an aluminum sintered alloy according to claim 3, wherein the strength is 25 kg / mm ² or more and the dimensional accuracy is high. 7. The method for producing an aluminum sintered alloy according to claim 3, wherein the compact has a density ratio of 70.
% Or more, and in a temperature range not lower than the liquidus generation temperature of the metastable phase generated by the rapid solidification of the powder and lower than the melting point of the powder, the sintered body is sintered to have a density ratio of 90% or more and 99% or less. 6. The method for producing an aluminum sintered alloy according to claim 3, wherein the tensile strength is 30 kg / mm ² or more. 8. The method for producing an aluminum sintered alloy according to claim 6, wherein the molten aluminum alloy contains 4.
0 to 40.0% by weight at the same time, if necessary, at least one component selected from Cu, Mn, Fe and Ni is contained without exceeding 2% by weight in total, and the balance is substantially 7. The method for producing an aluminum sintered alloy according to claim 6, which has a high dimensional accuracy, is excellent in wear resistance, and has a low coefficient of thermal expansion, which is a molten metal having a composition that is substantially made of aluminum. 9. The method for producing an aluminum sintered alloy according to claim 7, wherein the molten aluminum alloy contains Cu of 1.
0 to 8.0% by weight, and at the same time, 5.0 to 30.0% by weight in total of one or more components selected from Fe, Ni and Mn, and if necessary Si, Ti, Cr,
A molten metal having a composition containing 8% by weight or less of one or more kinds of components selected from V, Mo and Zr, and the balance being substantially aluminum, and having excellent wear resistance and a low coefficient of thermal expansion. The method for producing an aluminum sintered alloy according to claim 7, which comprises. 10. The method for producing an aluminum sintered alloy according to claim 3, wherein the molten aluminum alloy is selected from intermetallic compounds, carbides, oxides, nitrides, borides, and silicides. The method for producing an aluminum sintered alloy according to any one of claims 3 to 9, which is a melt containing at least one kind of particles added in an amount of 0.5 to 30% by volume and has excellent wear resistance and a low coefficient of thermal expansion. . 11. The manufacturing method according to claim 3, wherein during the steps from the production of the rapidly solidified powder to the compression molding,
0.5 to 30% by volume of at least one kind of particles selected from intermetallic compounds, carbides, oxides, nitrides, borides, and silicides is added to aluminum alloy powder and mixed, and mechanically pulverized if necessary. 10. The production of an aluminum sintered alloy according to claim 3, which has an excellent wear resistance and a low coefficient of thermal expansion, which is characterized in that a step of finely and uniformly integrating the aluminum alloy powder particles by a re-aggregation treatment is provided. Method. 12. The manufacturing method according to claim 3, wherein before the molding step, 0.4 to 4.0% by weight of Mg having a hardness lower than that of the aluminum alloy powder is contained, and the balance is substantially 85. The method for producing an aluminum sintered alloy according to claim 3, wherein 30% by weight or less of an aluminum alloy powder having a composition of aluminum by weight% or more is added and mixed.