JPH07207302A - Production of aln dispersion type aluminum alloy composite material - Google Patents

Abstract

PURPOSE:To easily produce an aluminum alloy composite material which is light in weight and is excellent in characteristics, such as rigidity, strength and wear resistance. CONSTITUTION:Aluminum alloy powder contg. Mg is prepd. The raw material powder obtd. by a raw material powder preparing stage is heated at <=600 deg.C and a temp. lower than the melting temp. of Al in a nitrogen-contg. atmosphere to form a nitride on the surface part of the raw material powder. The powder obtd. by a nitride forming stage is hot worked to a prescribed shape, by which the AlN dispersion type aluminum alloy composite material is produced.

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 AlN dispersed aluminum alloy composite material, and more specifically,
Used in automobiles, aircraft, etc., it is lightweight and has high rigidity,
The present invention relates to a method for producing an AlN-dispersed aluminum alloy composite material suitable as a metal material having excellent properties such as high strength and wear resistance.

[0002]

2. Description of the Related Art Aluminum (Al) alloy materials are widely used for aircraft parts and the like because of their low specific gravity and high specific strength. But on the other hand, compared to steel,
It has the drawback of being inferior in rigidity, high temperature strength and wear resistance. In order to compensate for this drawback of the Al alloy material, development of an Al alloy composite material in which ceramic particles or short fibers, whiskers, etc. are dispersed is being actively conducted.

As a method for producing a particle dispersion type Al alloy composite material in which ceramic particles are dispersed in an Al alloy, there are a powder method, a casting method, an in-situ process and the like. Among them, the powder method is a method of mixing Al alloy powder and ceramic particles and molding by HIP, hot extrusion, etc., and is most often used (for example, industrial material 36).
-11 (1988), 53). Further, the casting method is a method of stirring and mixing ceramic particles in an Al alloy melt to solidify (for example, industrial material 36-11 (1988),
53). Furthermore, the in-situ process is a method of reacting and dispersing a compound in an Al alloy to produce an Al alloy composite material, but it is still in a research stage (for example, light metal 40-12 (1990), 936). .

[0004]

However, the powder method is complicated in process and expensive. That is, in the powder method, after mixing the Al alloy powder and the ceramic powder, the mixture is held at a high temperature in a vacuum or a non-oxidizing atmosphere to remove surface adsorbates such as hydrogen and moisture, and then hot extrusion or hot extrusion is performed. By processing such as rolling, it is molded while destroying the oxide on the surface to manufacture a rod-shaped or plate-shaped member. Therefore, since these steps are complicated and long, and the cost of the ceramic particles is high, the particle-dispersed Al alloy produced by this method has a problem of being very expensive. Further, in this method, in the step of mixing the Al alloy powder and the ceramic powder, the agglomeration of the ceramic powder is likely to occur, and know-how is required for the mixing method in order to disperse the ceramic powder uniformly, which requires a lot of time. have. In particular, there is a problem that it is difficult to secure quality stability when manufacturing in large quantities.

Further, the casting method has a problem that it is difficult to disperse the ceramic particles in the aluminum alloy matrix and stable quality cannot be obtained.

Furthermore, the in-situ process is still in the research stage, and there remains a problem in controlling the dispersibility and size of the reaction product.

[0007] Therefore, the inventors of the present invention have earnestly studied to solve the problems of the prior art as described above, and as a result of various systematic experiments, the present invention has been accomplished.

(Object of the Invention) The object of the present invention is to be lightweight,
Another object of the present invention is to provide a method for easily producing an aluminum alloy composite material having excellent properties such as rigidity, strength, and wear resistance.

The present inventors have focused on the following points with respect to the above-mentioned problems of the prior art. That is, first, as a method for producing a ceramic particle-dispersed Al alloy composite material, detailed research was conducted on the above powder method, casting method, and in-situ process. As a result, although the powder method has many of the above problems, the material using the Al alloy powder can be manufactured by the casting method because the crystal grains can be refined and the crystallized substances and the precipitates can be refined. It has been found that it can exhibit superior mechanical properties compared to composite materials. Therefore, the inventors have earnestly conducted research to develop a method for providing an Al alloy composite material which has a simpler process and is superior in wear resistance while maintaining the advantages of the powder method.

First, as ceramic particles to be dispersed in an Al alloy, attention was focused on aluminum nitride (AlN), which can be generated from an Al alloy powder as a raw material powder and is excellent in characteristics such as rigidity, strength and abrasion resistance of the AlN alloy. . However, in order to generate AlN from the Al alloy, it was necessary to heat the Al alloy to 800 ° C. or higher and react it with nitrogen in a molten state. Therefore, it has been considered impossible to generate AlN on the surface of the Al alloy powder at a melting temperature or lower, for example, 600 ° C. or lower. Moreover, since Al is in a molten state in the nitriding treatment in such a temperature range, its shape cannot be maintained for nitriding the Al alloy powder as a compact.

The present inventors have found that as a method of producing AlN at a temperature below the melting temperature of Al, for example, below 600 ° C., without the need for a catalyst, in the Al alloy raw material powder within the above temperature range, Coexisting with a substance that reduces or destroys a substance that inhibits the production of AlN, or
The present inventors have focused on coexistence of a substance that promotes AlN production and / or a substance that serves as a nucleus of AlN production even if an N production inhibitor exists. Therefore, by focusing on Mg as a substance that reduces or destroys a substance that inhibits the generation of AlN within a temperature range of 600 ° C. or lower, and using a Mg-containing Al alloy powder as a starting raw material, the raw material is melted at a temperature not higher than the melting temperature of Al. AlN can be easily generated on the powder surface, and by subjecting the AlN alloy powder having AlN generated on the surface portion to plastic deformation, an aluminum alloy composite material having excellent rigidity, strength, and wear resistance can be obtained. It reached, and came to complete the present invention.

[0012]

A method of manufacturing an AlN-dispersed aluminum alloy composite material according to the present invention comprises a raw material powder preparation step of preparing an aluminum alloy powder containing Mg,
A raw material powder obtained by the raw material powder preparation step is heated in a nitrogen-containing atmosphere to generate a nitride on the surface portion of the raw material powder, and a powder obtained by the nitride production step is predetermined. Hot working process of hot working into the shape of
It is characterized by consisting of.

[0013]

The mechanism by which the method for producing an AlN-dispersed aluminum alloy composite material of the present invention exerts an excellent effect is not always clear, but it is considered as follows.

In the method for producing an AlN dispersed aluminum alloy composite material of the present invention, first, an aluminum alloy powder containing Mg is prepared (raw material powder preparation step).

Next, the raw material powder obtained in the raw material powder preparing step is heated in a nitrogen-containing atmosphere to generate a nitride on the surface portion of the raw material powder (nitride producing step). From this, in the present invention, since the Al alloy powder containing Mg is used,
Only by heating in a nitrogen atmosphere at a low temperature of 600 ° C. or lower, which is lower than the melting temperature of Al, Al is nitrided without the need for a catalyst, and AlN can be generated on the powder surface. At this time, it is considered that Mg existing on the surface of the Al alloy powder has an action of reducing or destroying an oxide film which is considered to be a substance that inhibits surface reactions such as generation of AlN and further oxidation to the inside. It is considered that Al on the surface is nitrided by the destruction of the oxide film and AlN is generated. In the temperature range of 600 ° C or lower,
The Al alloy is in the solid phase or semi-solid phase region, and in the manufacturing process of the material using the Al alloy powder, the Al alloy composite material,
That is, it becomes possible to manufacture an AlN dispersed Al alloy material.

Next, the powder obtained in the nitride forming step is hot worked into a predetermined shape (hot working step). That is, the AlN powder generated on the surface is subjected to hot working. Since AlN is a hard but extremely brittle substance, when the Al alloy powder is plastically deformed by hot working, it breaks and is dispersed in the Al alloy. At this time, the greater the degree of processing, the finer the AlN can be broken, and the better the dispersibility.
In addition, bonding between Al alloy powders, and Al alloy and Al
The N bond also becomes stronger. As a result, the structure is such that AlN is finely and uniformly dispersed in the Al alloy matrix. Therefore, the properties of the Al alloy such as rigidity (Young's modulus), room temperature and high temperature strength, and wear resistance can be improved.

Therefore, in the usual Al alloy powder material manufacturing process, the atmosphere is replaced with a nitrogen atmosphere and the temperature and time control conditions are changed.
It becomes possible to easily manufacture the AlN dispersed Al alloy composite material. Further, in the hot working step, since the bonding between the Al alloy powders can be performed by hot working, it is not necessary to consider the cleanliness of the powder surface as in the case of the usual powder method. Further, in the hot working step, the working degree is increased to destroy AlN formed on the surface of the Al alloy powder.
An AlN dispersion type Al alloy composite material can be manufactured only by dispersing.

From the above, it is considered that the particle-dispersed Al alloy composite material which is lightweight and has excellent properties such as rigidity, strength and wear resistance can be easily produced at low cost.

Conventionally, as a method of producing AlN powder, there is a method of producing pure Al powder by heating and holding it in nitrogen gas. However, this method requires a catalyst for the production of AlN and requires a heating temperature of 1000 ° C. or higher. Therefore, since Al is in a molten state,
There is a problem that the shape cannot be maintained when the powder is nitrided as a compact. The problems of these conventional techniques can be solved by the method for producing an AlN-dispersed aluminum alloy composite material of the present invention.

[0020]

EFFECTS OF THE INVENTION By the method for producing an AlN-dispersed aluminum alloy composite material of the present invention, it is lightweight and has high rigidity, strength,
An aluminum alloy composite material having excellent properties such as wear resistance can be easily manufactured.

[0021]

EXAMPLES First, the method for producing an AlN-dispersed aluminum alloy composite material (referred to as the first invention) of the present invention will be described with respect to other specific inventions (limited inventions) (other inventions).

[Description of Other Inventions]

Description of Second Invention The method for producing an AlN-dispersed aluminum alloy composite material according to the second invention is obtained by a raw material powder preparing step of preparing an aluminum alloy powder containing Mg and the raw material powder preparing step. Raw material powder in a nitrogen-containing atmosphere at 500 ° C
To a temperature range of 600 ° C. to generate a nitride on the surface portion of the raw material powder, and a hot working for hot working the powder obtained by the nitride generating step into a predetermined shape. And a processing step. The operation and effects of the present invention will be described below, focusing on the differences from the first invention.

(Function of the Second Invention) The mechanism by which the method for producing an AlN-dispersed aluminum alloy composite material of the present invention exhibits excellent effects is not yet clear, but it is considered as follows. That is, in the present invention, first, an aluminum alloy powder containing Mg is prepared (raw material powder preparation step).

Next, the raw material powder obtained by the raw material powder preparation step is treated in a nitrogen-containing atmosphere at 500 ° C. to 600 ° C.
Heating is performed within a temperature range of ° C to generate a nitride on the surface portion of the raw material powder (nitride generating step). In this step, when an Al alloy powder as a raw material powder is filled in a container or heated and held in a nitrogen-containing gas as a green compact, the heating temperature is 500 to 600 ° C. Heating temperature is 500-600
By setting the temperature within the range of ℃, A on the surface of the Al alloy powder
In addition to being able to generate 1N, the AlN can be generated in a relatively short time. Note that, depending on the type of Al alloy, if the heating temperature exceeds 550 to 600 ° C., the Al alloy powder may melt and the shape of the green compact may not be maintained, so attention must be paid to various conditions. Further, in the temperature range, shrinkage of the molded body occurs rapidly at the time of producing AlN, nitrogen gas may not penetrate into the inside of the molded body, and it may be difficult to uniformly generate AlN in the entire molded body. Therefore, be careful in setting the conditions.
Therefore, it is preferable that the heating temperature is in the range of 500 ° C. to 550 ° C., since these problems do not occur and sufficient AlN can be produced. Furthermore, when the heating temperature is 500 ° C. to 530 ° C., the effect of the present invention can be further exerted, which is more preferable.

(Effect of the Second Invention) The method for producing an AlN-dispersed aluminum alloy composite material of the present invention makes it lightweight and
In addition, an aluminum alloy composite material having excellent properties such as rigidity, strength, and wear resistance can be easily manufactured in a relatively short time.

Description of Third Invention The method for producing an AlN-dispersed aluminum alloy composite material of the third invention is obtained by a raw material powder preparing step of preparing an aluminum alloy powder containing Mg and the raw material powder preparing step. Raw material powder in a nitrogen-containing atmosphere at 450 ° C
A nitride forming step of forming a nitride on the surface of the raw material powder by heating within a temperature range of not less than 500 ° C. and heat of hot working the powder obtained by the nitride forming step into a predetermined shape. And an inter-working step.

(Operation of Third Invention) The mechanism by which the method for producing an AlN-dispersed aluminum alloy composite material of the present invention exhibits excellent effects is not yet clear, but it is considered as follows. That is, in the present invention, first, an aluminum alloy powder containing Mg is prepared (raw material powder preparation step).

Next, the raw material powder obtained by the raw material powder preparation step is heated in a nitrogen-containing atmosphere at 450 ° C. or higher and 50 ° C. or higher.
Heating is performed within a temperature range of less than 0 ° C. to generate a nitride on the surface portion of the raw material powder (nitride forming step). In the present invention, since the Al alloy powder containing Mg is used as the raw material powder as the object to be processed, by heating at a low temperature below the melting temperature of Al of less than 500 ° C. in a nitrogen atmosphere, Al can be used without a catalyst. Can be nitrided to form AlN on the powder surface. At this time, Mg in the Al alloy powder is
It is considered to have the action of reducing or destroying the oxide film, which is considered to be a substance that inhibits surface reactions such as generation of AlN and further oxidation to the inside. It is considered that Al on the surface is nitrided by the destruction of the oxide film and AlN is generated. At this time, the raw material powder as the object to be treated may be in the form of powder or may be preformed. When a powdery raw material is used as the object to be processed, it may be subjected to nitriding treatment as it is, or may be placed in a container and subjected to nitriding treatment, or simultaneously molded.

The heating temperature range in this step is 4
It is 50 ° C or higher and lower than 500 ° C. When the heating temperature range is set to the range, the heating temperature range of the second invention (500 ° C to
Compared with the case of 600 ° C., the amount of shrinkage of the object to be heated due to sintering during heating becomes smaller. Further, although nitriding of Al is an exothermic reaction, in the temperature range, the temperature rise of the heated object is suppressed, and the shrinkage of the heated object due to this temperature increase is suppressed. As a result, nitrogen can be sufficiently supplied to the inside of the object to be heated for a long time, and a large amount of nitride can be generated.

Next, the powder obtained by the nitride forming step is hot worked into a predetermined shape (hot working step). At this time, since AlN is a hard but very brittle substance, when the Al alloy powder is plastically deformed by hot working, it breaks and is dispersed in the Al alloy. At this time, the greater the degree of processing, the finer the AlN can be broken, and the better the dispersibility.
In addition, bonding between Al alloy powders, and Al alloy and Al
The N bond also becomes stronger. From this, as in the Al alloy composite material in which ceramic powder is mixed with the Al alloy,
lN has a structure in which AlN is finely and uniformly dispersed in the alloy matrix. Therefore, the properties of the Al alloy such as rigidity (Young's modulus), room temperature and high temperature strength, and wear resistance can be improved.

Therefore, in the usual Al alloy powder material manufacturing process, the atmosphere is replaced by a nitrogen atmosphere and the temperature and time control conditions are changed.
It is considered that the AlN dispersed Al alloy composite material can be easily manufactured. Further, in the hot working step, since the bonding between the Al alloy powders can be performed by hot working, it is not necessary to consider the cleanliness of the powder surface as in the case of the usual powder method. Further, in the hot working step, the degree of working is increased and the AlN formed on the surface of the Al alloy powder is simply destroyed and dispersed to obtain AlN-dispersed Al.
Alloy composite materials can be manufactured. The above steps of the present invention are not particularly limited except for the matters described as the above configuration, but in such a conventional manufacturing process of the powder method, the heating atmosphere is simply replaced with a nitrogen-containing atmosphere, and other than that, The nitride-dispersed Al alloy composite material according to the present invention can be easily manufactured only by considering heating conditions, processing conditions and the like. In particular, in a single manufacturing process using a green compact, an AlN-dispersed Al alloy composite member can be manufactured only by controlling the heating temperature and time in a nitrogen-containing atmosphere, and the volume ratio of the nitride can be adjusted in a wide range. It can be changed. Further, by using the Al alloy powder filled in the container, it is possible to generate the nitride in an amount of approximately 50% or more in volume ratio.

From the above, it is considered that the particle-dispersed Al alloy composite material which is lightweight and has excellent properties such as rigidity, strength and wear resistance can be easily produced.

(Effect of the Third Invention) The method for producing an AlN-dispersed aluminum alloy composite material according to the present invention makes it lightweight and
Moreover, an aluminum alloy composite material excellent in properties such as rigidity, strength, and wear resistance can be easily manufactured. Further, according to the manufacturing method of the present invention, it is possible to manufacture an aluminum alloy composite material in which a large amount of AlN is dispersed.

Description of Fourth Invention The method for producing an AlN-dispersed aluminum alloy composite material according to the fourth invention is obtained by a raw material powder preparation step of preparing an aluminum alloy powder containing Mg and the raw material powder preparation step. The raw material powder is first placed in a nitrogen-containing atmosphere and
Heating in a temperature range of 0 ° C. or higher (first heat treatment step),
Then, in a nitrogen-containing atmosphere and in a temperature range of 450 ° C. or higher and lower than 500 ° C. lower than the heating temperature of the first heat treatment step (second heat treatment step), the surface of the raw material powder is nitrided. It is characterized by comprising a nitride forming step of forming and a hot working step of hot working the powder obtained by the nitride forming step into a predetermined shape. The operation and effects of the present invention will be described below, focusing on the differences from the first and third inventions.

(Operation of Fourth Invention) The mechanism by which the method for producing an AlN-dispersed aluminum alloy composite material of the present invention exhibits excellent effects is not always clear, but it is considered as follows. That is, in the present invention, first, an aluminum alloy powder containing Mg is prepared (raw material powder preparation step).

Next, the raw material powder obtained by the raw material powder preparing step is heated in a nitrogen-containing atmosphere and in a temperature range of 480 ° C. or higher (first heat treatment step), and then in a nitrogen-containing atmosphere. The first temperature above 450 ° C and lower than 500 ° C
Heating is performed within a temperature range lower than the heating temperature of the heat treatment step (second heat treatment step), and nitride is generated on the surface portion of the raw material powder (nitride generation step). As a result, a large amount of AlN can be produced in a short time as compared with the third invention. That is, at the start of heating, the heat treatment is performed within a relatively high temperature range of 480 ° C. or higher (in the case of a green compact and lower than the melting temperature of Al) to accelerate the time until the start of the nitriding reaction (first heat treatment). Process), and then by lowering the heating temperature to a range of 450 ° C. to less than 500 ° C., it is possible to control the nitriding reaction accompanied by heat generation, suppress the shrinkage of the object to be processed, and generate a large amount of nitride in a short time. It is possible (second heat treatment step). In the first heat treatment step, the nitrogen-containing atmosphere may be set before the start of the nitriding reaction (when the non-nitrogen-containing atmosphere is initially set, AlN
It is preferable that the atmosphere is such that is easily generated. That is,
At least, the atmosphere is such that a substance that inhibits the generation of AlN is not formed in the object to be processed. ). In the first heat treatment step, the heating temperature is preferably 480 ° C to 600 ° C when the object to be heated has a predetermined shape such as a green compact that is preformed. Further, the temperature is more preferably 480 ° C to 550 ° C. Within this range, the effects of the present invention can be better exhibited without causing problems such as melting of the Al alloy powder. Further, when the object to be heated does not have a predetermined shape such as a green compact, for example, a powder, the heating temperature is preferably 480 ° C to 800 ° C. Unlike the above, the Al alloy powder may melt to some extent as long as a predetermined amount of AlN can be generated in the second heat treatment step of the next step. Further, the temperature is more preferably 480 ° C to 600 ° C.
In this case, a larger amount of AlN can be produced in the next step.

Next, the powder obtained by the nitride forming step is hot worked into a predetermined shape (hot working step). As a result, the structure is such that AlN is finely and uniformly dispersed in the Al alloy matrix. Therefore, the properties of the Al alloy such as rigidity (Young's modulus), room temperature and high temperature strength, and wear resistance can be improved. The above steps of the present invention include
There is no particular limitation except for the matters described as the above configuration, but in the manufacturing process of the conventional powder method in this manner, the heating atmosphere is simply replaced with the nitrogen-containing atmosphere, and other heating conditions and processing conditions are set. The AlN-dispersed Al alloy composite material according to the present invention can be easily manufactured only by considering it. In particular, in a single manufacturing process using a green compact, an AlN-dispersed Al alloy composite member can be manufactured only by controlling the heating temperature and time in a nitrogen-containing atmosphere, and the volume ratio of the nitride can be adjusted in a wide range. It can be changed. Further, by using the Al alloy powder filled in the container, it is possible to generate the nitride in an amount of approximately 50% or more in volume ratio.

From the above, it is considered that the particle-dispersed Al alloy composite material which is lightweight and has excellent properties such as rigidity, strength and wear resistance can be easily produced in a relatively short time.

(Effect of the Fourth Invention) The method for producing an AlN-dispersed aluminum alloy composite material of the present invention makes it lightweight and
In addition, an aluminum alloy composite material excellent in properties such as rigidity, strength, and wear resistance can be easily manufactured in a relatively short time. Further, according to the manufacturing method of the present invention, an aluminum alloy composite material in which a large amount of AlN is dispersed can be manufactured.

Other Inventions of the First to Fourth Inventions

(Raw Material Powder Preparation Step) In the method for producing an AlN dispersed aluminum alloy composite material of the present invention, the Al alloy powder prepared in this step has a particle size of 149 μm (10 μm).
It is preferably 0 mesh or less). If the particle size exceeds 149 μm, the surface area decreases, so that it takes a long time to generate a predetermined amount of nitride, and the AlN dispersion after hot working may become uneven. In addition,
When the particle size is in the range of 20 to 50 μm, AlN after hot working can be dispersed more uniformly, which is more preferable. On the other hand, if it is less than 20 μm, the handling of the powder becomes poor, which is not preferable.

Further, M contained in the prepared Al alloy powder
g is a substance that realizes the generation of AlN on the surface of the Al alloy in an atmosphere having a temperature equal to or lower than the melting temperature of Al in the subsequent nitride generation step. That is, it is considered that it exerts an action of reducing or destroying an oxide film which is considered to be a substance that inhibits a surface reaction such as generation of AlN and further oxidation to the inside. As a result, AlN can be formed on the surface of the Al alloy powder without melting the Al alloy powder. The content of this Mg in the Al alloy powder is 0.2 to 5% by weight.
Is preferred. In this range, an AlN layer having a practically sufficient thickness and / or a sufficient amount of AlN can be produced.

Next, when the Al alloy powder is pressure-molded into a green compact, the density ratio of the green compact to the theoretical density is 6
0 to 85% is preferable. If the density ratio is less than 60%, the shape of the green compact cannot be maintained, which may make it difficult to convey the green compact. In this case, it is preferable to adopt a means for maintaining the shape such as filling the container with Al alloy powder. When the container is filled with the Al alloy powder, in order to uniformly nitride the Al alloy powder in the container in the subsequent nitride generation step, the nitrogen-containing gas is supplied from the bottom of the container. It is preferable to employ a means for uniformly flowing. Further, if the density ratio exceeds 85%, nitrogen gas may not penetrate into the inside of the powder, and uniform AlN is difficult to be generated.

(Nitride forming step) The holding time is controlled according to the heating temperature according to the amount of AlN formed.
The conditions of the nitrogen atmosphere are not particularly limited. For example, it may be an atmospheric furnace in which nitrogen gas used for ordinary industry is introduced. Therefore, the condition control is not as strict as the atmosphere for degassing. Also, fill the container with AlN
In order to form AlN uniformly,
After processing once, invert the open part and bottom of the container,
Further, it is preferable to reheat and hold.

Also, when the Al alloy powder is filled in a container to generate a nitride, the heating temperature and time are almost the same as those of the green compact.

Further, in the formation of AlN, a fluidized bed furnace using nitrogen gas as a fluidizing gas is used to heat the Al alloy powder in nitrogen gas so that the Al alloy powder does not solidify, and a uniform AlN layer is formed on the surface. You may manufacture the Al alloy powder which formed. At this time, the heating temperature range is the same as described above, and the heating holding time is also controlled in accordance with the amount of AlN to be generated in accordance with the heating temperature in the same manner as described above. The AlN alloy powder in which the AlN layer is formed is compacted and heated, and the following hot working is performed.

In this way, the AlN compounded into the Al alloy
The amount can be controlled by controlling the density of the green compact, the heating temperature, and the heating time.

(Hot Working Step) Next, hot working is performed with Al.
There is no particular limitation as long as uniform plastic deformation can be given to the entire alloy powder (including various forms such as powder, compact, green compact, etc.), and hot extrusion or hot rolling that is usually performed. Alternatively, a method such as forging and swaging can be adopted.

The processing temperature is preferably in the range of 400 to 500 ° C. In the hot working, the Al alloy powder (or its compact or green compact) heated to a nitride generation temperature of 600 ° C. or lower in a nitrogen atmosphere is directly cooled to the hot working temperature or once cooled to room temperature. After that, it is preferable to reheat to the hot working temperature and then perform. It is preferable to heat in a vacuum or a non-oxidizing atmosphere. In the hot working, when a mold is used, it is preferable to heat the mold temperature to 300 to 500 ° C. in order to suppress cooling during processing by the mold. Preferably, the hot working temperature, which is the temperature of the molded body, and the mold temperature are equal. As a result, it is possible to select the processing temperature and the processing speed at which the ductility of the molded product is highest.

When hot working is carried out by hot extrusion,
The extrusion ratio is preferably 10 or more. If it is less than 10, the AlN formed on the surface of the Al alloy powder cannot be finely broken and dispersed uniformly. The larger the extrusion ratio, the better. The upper limit of the extrusion ratio may be determined by the relationship between the deformation resistance of the Al alloy determined by the extrusion temperature and the extrusion speed and the die strength.

When hot working is performed by hot rolling, the rolling conditions, that is, working temperature, working speed, and mold temperature are the same as those in hot extrusion, and the reduction rate indicating the working degree is preferably 80% or more.

Examples of the present invention will be described below.

[0054]First embodiment First, as the raw material powder, the particle size is 74 μm (200 mesh).
Al alloy powder below (A2024: Al-4.3)
wt% Cu-0.6 wt% Mn-1.5 wt% Mg) was prepared.
Next, the raw material powder was processed under the molding treatment conditions [ρ (
Feature density) / ρ ₀(Theoretical density)]
It was filled.

[0055]

[Table 1]

Next, the obtained green compact (processed compact)
Then, the nitriding treatment was performed under the heating conditions shown in Table 1. After the nitriding treatment, a part of the molded body to be treated was solidified by hot coining and the metal structure of the sample cross section was analyzed by EPMA. As a result, on each surface of the Al alloy powder forming the molded body,
It was confirmed that a film containing Al and N as main components was produced. Moreover, as a result of confirming the crystal structure by the X-ray diffraction method, it was confirmed that the film formed on the surface of the Al alloy powder was dense hexagonal AlN. That is, the film is not a compound containing Mg. This crystallized AlN
Is a very hard substance with a Mohs hardness of 9 according to the Chemical Manual. Here, the metallographic structure of the sample surface after heat treatment of the molded body of sample number 1 in a nitrogen atmosphere was EPM.
The results analyzed in A are shown in FIGS. 1 and 2.

Then, hot extrusion was performed. For hot extrusion, the heating temperature is 500 ° C, the mold temperature is 350 ° C, and the extrusion ratio is 1.
2 was performed to pulverize the AlN formed on the surface of the Al alloy powder. Then, the sample was subjected to T6 treatment (solution treatment 490 ° C., aging 180 ° C. × 8 hours), and three kinds of AlN-dispersed Al alloy composite material members of the first example according to the present invention were produced (sample numbers: 1 to 3). ).

(Performance Evaluation Test) First, the AlN volume ratio, hardness, tensile strength, and elongation of the obtained Al alloy composite member were measured. The results are shown in Table 2. AlN
The volume ratio was obtained by measuring the specific gravity after extrusion and calculating from the specific gravity of the Al alloy and AlN of this example. The hardness was measured using a Vickers hardness meter. At this time,
The load was 1 kg. The tensile strength was measured by a universal testing machine. At this time, the diameter of the test piece used was 5 m
m, the gauge length is 30 mm. In the production of the test piece, the material extruding direction was the pulling direction of the test piece. The elongation was determined by measuring the distance between the gauge marks after breaking.

[0059]

[Table 2]

Next, the results of observing the metal structure of the cross section of the obtained Al alloy composite member with an optical microscope (magnification: 100 times) are shown in FIG. 3 for sample No. 1, FIG. The number 3 is shown in FIG. 5, respectively. In any case, it can be seen that AlN generated on the surface of the Al alloy powder is crushed and AlN is dispersed in the Al alloy matrix.

Next, the obtained Al alloy composite material member was subjected to a wear resistance test by the pin-on-disk method. The Al alloy composite material member obtained in this example was used for the pin test piece, and S55C (Hv300) was used for the disk material (counterpart material). Surface pressure 50k in base oil (mineral oil without additive) kept at 100 ℃
The pin was pressed against the disk at gf / cm ² , the sliding speed was set to 0.3 m / s, and it was slid for 30 minutes, and then the weight change of the pin and the disk was measured to obtain the wear amount. It was The obtained results are shown in FIG. In the figure,
The horizontal axis indicates the type of test piece, and the vertical axis indicates the weight change of the pin and disk.

Comparative Examples 1 to 3 As comparative examples, a comparative Al alloy member (sample number: C1) which is not subjected to nitriding treatment with the same type of Al alloy as in this example,
The same Al alloy powder (A2024) as in this example was used.
% SiC powder (particle size 2 μm) was dispersed by a known powder mixing method to obtain a comparative Al alloy composite material member (sample number: C2), and a known wear-resistant Al alloy (Al-17).
% Si alloy) member (sample number: C3) was prepared. Note that the comparative Al alloy composite material member of sample number C2 was hot-worked after mixing SiC powder and Al alloy powder,
The wear-resistant Al alloy of Sample No. C3 was produced by hot working the rapidly solidified powder. These are Al alloys in which Si and SiC are dispersed and are currently used as wear resistant materials. With respect to the obtained comparative member, the sample No. C1 was measured for AlN volume ratio, hardness, tensile strength, and elongation in the same manner as in the above-mentioned Example. The obtained results are also shown in Table 2. Further, with respect to the comparative numbers C1, C2, and C3, the same abrasion resistance test as in the above example was also performed. The obtained results are also shown in FIG.

(Results of Performance Evaluation Test) As is clear from Table 2, in the Al alloy composite material member obtained in this example, the elongation decreases as the volume ratio of AlN increases, but the hardness, It can be seen that the tensile strength is increasing. It should be noted that all of these measured values are superior to those of the comparative member (A2024) which is not subjected to the nitriding treatment of Comparative Example C1.

Further, as is clear from FIG. 6, it is understood that the Al alloy composite material member obtained in this example has a small amount of wear, and the disk as the mating material is hardly worn. Further, it can be seen that the wear amount decreases as the production amount of AlN increases. Note that the comparative members of sample numbers C1 and C3 both have large amounts of wear. Further, the comparative composite member in which the SiC powder of the sample number C2 is dispersed has a problem that the material cost is high although the amount of wear is hardly observed.

From the above, it can be seen that by the method of this embodiment, an AlN dispersion type Al alloy composite material can be obtained easily and at low cost, and the composite material is lightweight and has excellent wear resistance. . In addition, according to the present embodiment, AlN dispersion type A
It can be seen that the Al alloy composite material has particularly excellent properties when the volume ratio of AlN is 10% or more.

Second Example As raw material powders, four kinds of Al alloy powders having different Mg contents were prepared, and the Al alloy powders were filled in respective containers,
The raw material powder was used as a compact. Next, the obtained molded body was subjected to a nitride generation treatment under heating conditions of a heating temperature of 540 ° C. and a heating and holding time of 1 hour, and the weight change rate of each powder was obtained (sample number: 4 to 7). ). The obtained results are shown in FIG.
Shown in. The ratio of the density (ρ) of the green body before heating to the theoretical density (ρ ₀ ) is about 50%.

Sample number 4: A2024 (Al-1.5 wt% Mg-4.3 wt% Cu-0.6 wt% Mn) Sample number 5: A5052 (Al-2.5 wt% Mg-0.25 wt% Cr) Sample number 6 : A6061 (Al-1.0 wt% Mg-0.27 wt% Cu-0.6 wt% Si-
0.2 wt% Cr) -Sample No. 7: A7475 (Al-2.5 wt% Mg-1.6 wt% Cu-5.6 wt% Zn-
0.26wt% Cr)

Regarding the object to be treated after the nitride formation treatment, the metallographic structure of the sample cross section was EP as in the first embodiment.
As a result of analysis by MA, it was confirmed that a film containing Al and N as main components was formed on the surface of the Al alloy powder forming the molded body. Moreover, as a result of X-ray diffraction, it was confirmed that all were AlN.

Next, these nitriding molded bodies were subjected to hot extrusion and T6 treatment in the same manner as in the first embodiment, and four kinds of Al alloy composite material members were produced. In each case, this composite material member was formed with A produced on the surface of the Al alloy powder.
It was confirmed that 1N was crushed and AlN was uniformly dispersed, that it was lightweight and had excellent wear resistance.

Comparative Examples 4 to 6 For comparison, three kinds of Al alloy powder not containing Mg were prepared, and the Al alloy powder was filled in each container in the same manner as in the second embodiment, and the heating temperature was set to 540. Nitride formation treatment was performed at a temperature of 1 hour for 1 hour at a temperature of ℃, and the weight change rate of each powder was determined (sample number: C4 to C6). The obtained results are also shown in FIG. The ratio of the density (ρ) of the green body before heating to the theoretical density (ρ ₀ ) is about 50%.

(Test Results) As is clear from FIG. 7, an Al alloy containing Mg in its composition (Sample Nos. 4 to 7)
Shows that the weight increases, that is, a large amount of AlN is produced, but the comparative Al alloys (Sample No. C4 to Sample No. C6) that do not contain Mg in the composition show almost no change in weight. That is, it can be seen that AlN is hardly generated.

Third Example The same Al alloy powder as the sample No. 4 of the second example was prepared, and the ratio of the density (ρ) of the green body before heating to the theoretical density (ρ ₀ ) of the green body was changed. Others were the same as in the second embodiment, except that the nitride generation treatment was performed to determine the weight change rate of each powder (sample number: 8 to 12). The obtained results are shown in FIG.

Regarding the object to be treated after the nitride formation treatment, the metallographic structure of the sample cross section was analyzed by EPMA as in the case of the second embodiment.
It was confirmed that a film containing Al and N as main components was formed on the surface of the 1-alloy powder. Moreover, as a result of X-ray diffraction, it was confirmed that all were AlN.

Next, these nitriding-formed compacts were subjected to hot extrusion and T6 treatment in the same manner as in the second embodiment to produce Al alloy composite material members. In any case, this composite material member is formed of AlN produced on the surface of the Al alloy powder.
Was crushed, AlN was dispersed in the Al alloy matrix, and it was confirmed that the alloy was lightweight and had wear resistance.

(Test Results) As is clear from FIG. 8, the lower the density of the green compact, that is, the more the voids between the powders,
It can be seen that a large amount of AlN is produced. However, in the case of this example, if the density ratio was less than 60%, the shape of the green compact could not be maintained, and it was difficult to convey the green compact. Therefore, in such a case, it has been found that a means for maintaining the shape, such as filling the Al alloy powder in the container, is necessary. Further, it was found that when the content exceeds 85%, the nitrogen gas does not penetrate into the inside of the powder, and uniform AlN is hardly produced.

Fourth Embodiment As a raw material powder, an Al alloy powder (A2024: Al-4.3 wt%) having a particle size of 74 μm (passing through 200 mesh) or less.
Cu-0.6 wt% Mn-1.5 wt% Mg) was prepared. Next, the raw material powder was molded into a green compact. Next, with respect to the obtained green compact (molding object to be treated), the heating temperature was changed in 5 steps, and the heating and holding time was 1 hour, so that the nitride generation treatment was performed (Sample Nos. 13 to 17). The ratio of the green compact density (ρ) before heating to the theoretical density (ρ ₀ ) was about 84%. Here, the weight change rate of each sample was obtained. The obtained results are shown in FIG.

Regarding the object to be processed after the nitride formation treatment, the metallographic structure of the sample cross section was analyzed by EPMA as in the case of the third embodiment.
It was confirmed that a film containing Al and N as main components was formed on the surface of the 1-alloy powder. Moreover, as a result of X-ray diffraction, it was confirmed that all were AlN.

Next, these nitriding-formed compacts were subjected to hot extrusion and T6 treatment in the same manner as in the third embodiment to produce Al alloy composite material members. This composite material member has different AlN contents, but in any case, A
It was confirmed that AlN generated on the surface of the 1-alloy powder was crushed and AlN was dispersed in the Al alloy matrix.

(Test Results) As is apparent from FIG. 9, in this example, the rate of weight change, that is, the peak of the amount of AlN produced, occurred at the heating temperature in the nitriding treatment near 540 ° C.
It can be seen that the temperature is decreased above the temperature. This is because at high temperature, the surface layer of the green compact rapidly nitrides, but on the other hand, the shrinkage that accompanies it closes the voids between the powders, hinders the nitrogen gas from entering the interior, and suppresses internal nitriding. It is thought to be because of this. As a result of simply filling the Al alloy powder in a container and heating it in a nitrogen atmosphere in the same manner as this example, it was found that the same result as this example was obtained.

Fifth Example As a raw material powder, an Al alloy powder having a particle size of 149 μm or less (A2024: Al-4.3 wt% Cu-0.6 wt% Mn-1.
5 wt% Mg) was prepared. Next, the raw material powder was molded into a green compact (φ30 × 23 mm). Next, the obtained green compact was heated at a heating temperature of 465 ° C. (Sample No. 18),
490 ° C (Sample No. 19), 510 ° C (Sample No. 2)
0), 530 ° C. (sample No. 21), and a nitride generation treatment was performed by heating and holding time in four steps. The ratio of the green compact density (ρ) before heating to the theoretical density (ρ ₀ ) is
It was about 65%.

Regarding the object to be processed after the nitride formation treatment, the metallographic structure of the cross section of the sample is EP as in the first embodiment.
As a result of analysis by MA, it was confirmed that a film containing Al and N as main components was formed on the surface of the Al alloy powder forming the molded body. Moreover, as a result of X-ray diffraction, it was confirmed that all were AlN.

Next, these nitriding-formed compacts were subjected to hot extrusion and T6 treatment in the same manner as in the first embodiment to produce Al alloy composite material members. The AlN volume ratio of the obtained composite material member was determined in the same manner as in the first embodiment. With respect to the obtained results, the relationship between the heating time at each heating temperature and the volume fraction of nitride is shown in FIG. In addition, in each case, it was confirmed that AlN generated on the surface of the Al alloy powder was pulverized and AlN was uniformly dispersed, and that this composite material member was lightweight and had excellent wear resistance. Was done.

(Test Results) As is clear from FIG.
In this example, when the heating and holding time in the nitride forming step is 1 hour, the higher the heating and holding temperature is, the larger the amount of nitrides generated is. However, the heating hold time is 16
In the case of time, the lower the heating and holding temperature, the larger the amount of nitrides produced. Moreover, when the heating temperature was 465 ° C., the amount of nitrides produced was as large as about 30% by volume. This is because the lower the heating temperature is, the more the shrinkage of the compact due to sintering during heating is suppressed, so the nitriding rate is slow and it is necessary to maintain heating for a long time. Can be done for a long time,
It is considered that a large amount of nitride can be produced.

Sixth Example As a raw material powder, an Al alloy powder having a particle size of 149 μm or less (A2024: Al-4.3 wt% Cu-0.6 wt% Mn-1.
5 wt% Mg) was prepared. Next, the raw material powder was molded into a green compact (φ30 × 23 mm). Next, the obtained green compact was heated and held at a heating temperature of 490 ° C. to perform a nitride formation treatment, and the relationship between the holding time and the change in the temperature of the green compact was examined (Sample No. : 22). The ratio of the green compact density (ρ) before heating to the theoretical density (ρ ₀ ) was about 65%.

As is clear from FIG. 11, since the nitriding reaction of Al is an exothermic reaction, the temperature of the green compact rises as the nitriding proceeds, and the nitriding reaction is promoted. However, as the temperature of the molded body increases, the amount of shrinkage of the molded body also increases, so that the nitrogen gas is not supplied inside the molded body, and the nitriding reaction is suppressed thereafter. This exothermic phenomenon also causes the formation of nitrides to be suppressed.

Seventh Example After using the same raw material powder as in the sixth example and performing the nitride formation treatment by changing the heating time in the nitride formation process variously, the first embodiment was carried out on the nitrided compact. Hot extrusion and T6 treatment were performed in the same manner as in the example to produce an Al alloy composite material member. The obtained composite material member was A in any case.
AlN generated on the surface of the alloy powder is crushed to produce AlN
Were uniformly dispersed, and it was confirmed that they were lightweight and had excellent wear resistance.

Here, the relationship between the heating and holding temperature until the temperature of the molded body in FIG. 11 of the sixth embodiment starts to rise (latent period: time until start of nitriding reaction) and the heating and holding temperature is shown. , Shown in FIG. As is clear from the figure, when the heating temperature is lower than 450 ° C., the heating holding time required to generate a large amount of nitride is considered to be several tens of hours, which is not suitable for practical use.

Eighth Example As a raw material powder, an Al alloy powder having a particle size of 149 μm or less (A2024: Al-4.3 wt% Cu-0.6 wt% Mn-1.
5 wt% Mg) was prepared. Next, the raw material powder was molded into a green compact (φ30 × 23 mm). Next, the obtained green compact was first heated at 500 ° C. for 1 hour, then the heating temperature was lowered to 480 ° C. and kept for 3 hours to perform a nitride formation treatment. The ratio of the green compact density (ρ) before heating to the theoretical density (ρ ₀ ) was about 65%.

Regarding the object to be treated after the nitride formation treatment, the metallographic structure of the sample cross section was EP as in the first embodiment.
As a result of analysis by MA, it was confirmed that a film containing Al and N as main components was formed on the surface of the Al alloy powder forming the molded body. Moreover, as a result of X-ray diffraction, it was confirmed that all were AlN.

Next, these nitriding-formed compacts were subjected to hot extrusion and T6 treatment in the same manner as in the first embodiment to produce Al alloy composite material members. The AlN volume ratio of the obtained composite material member was determined in the same manner as in the first embodiment. As a result, the volume ratio of AlN was about 30%. In addition, it was confirmed that this composite material member was lightweight and had very excellent wear resistance because AlN generated on the surface of the Al alloy powder was pulverized and AlN was more evenly dispersed. It was

[Brief description of drawings]

FIG. 1 is a diagram showing a result of EPMA analysis of a metal structure of a cross section of a molded body after nitriding treatment obtained in the first example of the present invention (Al-Kα ray image).

FIG. 2 is a view showing a result of EPMA analysis of a metal structure of a cross section of a molded body after nitriding treatment obtained in the first example of the present invention (N-Kα ray image).

FIG. 3 is an optical micrograph (magnification: 400 times) showing a metal structure of a cross section of an Al alloy composite member (sample number: 2) obtained in the first example of the present invention.

FIG. 4 is an optical micrograph (magnification: 400 times) showing a metal structure of a cross section of an Al alloy composite member (sample number: 3) obtained in the first example of the present invention.

FIG. 5 is an optical micrograph (magnification: 400 times) showing a metal structure of a cross section of an Al alloy composite member (sample number: 4) obtained in the first example of the present invention.

FIG. 6 is a diagram showing the results of a wear resistance test of the Al alloy composite member obtained in the first example of the present invention.

FIG. 7 is a diagram showing the amount of AlN produced in the molded body after the nitriding treatment obtained in the second embodiment of the present invention.

FIG. 8 is a diagram showing a relationship between a density ratio of a molded body before heating to a theoretical density and a weight change rate (AlN production amount) of a molded body after nitriding treatment obtained in a third example of the present invention. .

FIG. 9 is a diagram showing a relationship between a heating temperature and a weight change (amount of AlN produced) of the molded body after the nitriding treatment obtained in the fourth example of the present invention.

FIG. 10 is a diagram showing the relationship between the AlN volume ratio and the heating temperature / heating time of the Al alloy composite alloy member obtained in the fifth example of the present invention.

FIG. 11 is a diagram showing the relationship between the heating and holding time and the temperature of the green compact when the green compact is heat-treated in the nitride forming step of the sixth example of the present invention.

FIG. 12 is a diagram showing a heating temperature with respect to a heating temperature, which is a time until the start of a nitriding reaction when a green compact is heat-treated in the nitride forming step of the seventh embodiment of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Kawaura 1st 41st Yokomichi, Nagakute-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture Toyota Central Research Institute Co., Ltd.

Claims (4)

[Claims] 1. A raw material powder preparing step of preparing an aluminum alloy powder containing Mg, heating the raw material powder obtained by the raw material powder preparing step in a nitrogen-containing atmosphere, and forming a nitride on a surface portion of the raw material powder. And a hot-working step of hot working the powder obtained by the nitride-making step into a predetermined shape, the method for producing an AlN-dispersed aluminum alloy composite material. Method. 2. The method for producing an AlN-dispersed aluminum alloy composite material according to claim 1, wherein the heating temperature in the nitrogen-containing atmosphere in the nitride forming step is in the range of 500 ° C. to 600 ° C. . 3. The production of an AlN-dispersed aluminum alloy composite material according to claim 1, wherein the heating temperature in the nitrogen-containing atmosphere in the nitride forming step is in the range of 450 ° C. or higher and lower than 500 ° C. Method. 4. A first heat treatment step in which a nitride formation step is performed in a nitrogen-containing atmosphere and in a temperature range of 480 ° C. or higher, and a nitrogen-containing atmosphere and 450 ° C. or higher and 500 ° C. or higher.
A second heat treatment step of heating within a temperature range lower than the heating temperature in the first heat treatment step of less than 0 ° C., the AlN-dispersed aluminum alloy composite material according to claim 1. Production method.