WO1993009899A1

WO1993009899A1 - Method for degassing and solidifying aluminum alloy powder

Info

Publication number: WO1993009899A1
Application number: PCT/JP1992/001527
Authority: WO
Inventors: Toshihiko Kaji; Yoshinobu Takeda; Yuusuke Odani; Kiyoaki Akechi; Takao Tanji
Original assignee: Sumitomo Electric Industries, Ltd
Priority date: 1991-11-22
Filing date: 1992-11-20
Publication date: 1993-05-27
Also published as: EP0568705B1; JPH05320709A; DE69225469T2; JP3336645B2; KR930703101A; EP0568705A4; EP0568705A1; DE69225469D1; KR960007499B1

Abstract

A method for degassing and solidifying aluminum alloy powder is mprovided that can eliminate drawbacks inherent in a conventional method by making induction heating available for degassing means during processes of forming and solidifying aluminum powder and aluminum alloy powder. The method comprises the steps of pre-forming aluminum powder, aluminum alloy powder, aluminum composite alloy powder or powder mixtures of these powders and non-ferrous metal particles to a specific resistance of 0.2 $g(V) cm or lower, removing heat decomposable evaporation components by directly induction heating the pre-formed body in the normal pressure atmosphere so as to raise the temperature thereof to 400 C to 600 C while maintaining a temperature rise gradient over 300 C at 0.4 C/scm or higher, and reducing the hydrogen content to less than 10 ppm.

Description

,', Specification

Degassing and solidification of aluminum alloy powder

Technical field

The present invention relates to a method for degassing and solidifying rapidly solidified aluminum alloy powder.

Background art

Conventionally, various methods have been used as a method for molding and solidifying rapidly solidified aluminum alloy powder, such as an extrusion method, a HIP method, and a powder forging method. In order to solidify the powder, the powder must be heated in any way, and the quenching effect of the powder is lost at this time, and the properties are deteriorated. In order to prevent this, a method of heating quickly and in a short time is used. As described above, there is no patent claiming to rapidly perform heating for solidifying rapidly quenched aluminum alloy powder.

① USP4 4 3 5 2 1 3 "Method for Producing Aluminum Powder Alloy Products Having Improved Strength Properties;

Therefore, there is no patent for a method for induction heating of general powders, not only aluminum.

(2) USP 5 1 3 4 2 6 0 “Method and Apparatus for Inductively Heating Powders or Powder Compacts for Consolidation: Carnegie Mellon University” is a patent for a method of rapid heating by hot air. Is

③ Japanese Patent Laid-Open No. 3-15804001 "How to heat rapidly solidified powder" Law; Kubota J

There is.

In any of the above-mentioned powder forging method, the conventionally known extrusion method, and the HIP method, the heating before solidification is performed by (1) reducing the deformation resistance of the powder and forming with low stress, (2) degassing, It is indispensable in these two respects.

In particular, degassing is an essential means for preventing air bubbles called blisters that appear in a solidified product and for firmly adhering powders to each other in powder forging. There are known techniques such as the method described in Japanese Patent Application Laid-Open No. 2-246264 and the method described in “Light Metal J 37 (10) 1989, pp. 656-6664. You.

In the known art, degassing is generally performed by enclosing a CIP body in a can and heating it in a vacuum or heating it to 400 to 600 ° C in an inert gas atmosphere. In all methods, conventional resistance heating furnaces are used, and sufficient degassing is achieved in a total of 1 to 4 hours, for 0.5 to 2 hours to raise the temperature and 0.5 to 2 hours to maintain the predetermined temperature. I was trying.

However, in the above-mentioned degassing method, the effect of rapid cooling of the powder, that is, the effect that the elements and phases that would normally precipitate if the cooling rate is small are small and uniform, and that the crystals are fine The effect of granulation is lost by prolonged heating, and the properties of the molded solid degrade. In addition, in order to prevent oxidation, it is necessary to control the atmosphere. Leading to higher costs, The disadvantage has been pointed out in the past.

,

It is generally difficult to rapidly and uniformly heat an object having low thermal conductivity, such as an embossed body. Usually, the most industrially suitable method for rapid heating is induction heating. For example, Japanese Patent Application Laid-Open No. 491-133453 discloses that high-frequency induction heating is used for heat sintering of powder molded products in iron-based metal powder metallurgy. You. Conventionally, high-frequency heating has been used for preheating of short-time sintering or sintering forging (forging to increase the density of preformed sintering).

However, the use of induction heating for degassing of aluminum powder and aluminum alloy powder powder molded products has not been conventionally performed. The reasons for this are as follows.

The surface of aluminum powder and aluminum alloy powder has an aluminum (A1203) film that is stable and has poor electrical conductivity. It becomes larger, resulting in a lower electrical conductivity of the embossed body, and in the case of a material having a low electrical resistance, such as aluminum, the heat of the Joule. Eddy currents are unlikely to occur when the powder is hardened, and the permeability of aluminum itself is smaller than that of iron-based ones. This is because it was thought that induction heating could not be performed efficiently.

Also, even if heating is possible, the thermal conductivity of the embossed body This was because the temperature difference between the surface and the center of the embossed body became large, and it was thought that heating to a uniform temperature was impossible.

In view of the above situation, the present invention provides the above-described conventional method so that induction heating can be used as a degassing means in the molding and solidifying process of aluminum powder and aluminum alloy powder. It is an object of the present invention to provide a method for degassing an aluminum alloy powder which has solved the above disadvantages.

When solidifying rapidly solidified aluminum alloy powder, the following must be considered.

(A) Minimize the thermal history applied to the powder in order to minimize the deterioration of the powder structure due to heating for solidification. -

(B) Strengthen the bond between the aluminum powders.

(C) Solidifies at low cost.

In order to achieve (A), the rapid heating method using hot air heating is also advantageous for induction heating as in the above three patents. However, the rapid heating method had a disadvantage that the aluminum powders of (B) were not easily bonded to each other. Therefore, as shown in the example of the patent of (1), the material heated in the air has a low elongation at break even when extruded. To compensate for this, rapid heating is performed in an inert gas, vacuum degassing is performed before solidification, or large after solidification. There was a need to improve the elongation and fracture toughness of the solidified material by extruding and upsetting to generate severe plastic deformation. Patent (3) provides an apparatus for rapid heating in a vacuum. However, the addition of these steps cannot achieve the purpose of solidifying with the safe cost of (C).

The present invention provides a solution to all of the above problems (A), (B), and (C), and is less expensive than any conventional solidification method, and solidified by any conventional solidification method. The present invention provides a solidified body having both excellent strength and toughness without deteriorating any mechanical properties as compared with the above, and a solidification method for obtaining the same.

Disclosure of the invention

The present inventors have made various studies to solve the above-mentioned problems, and as a result, have reduced the heating time to about 110 by using induction heating to reduce the aluminum time. The present inventors have found a method for degassing while suppressing the deterioration of the aluminum and aluminum alloy powders, leading to the present invention.

That is, the present invention is to remove aluminum powder, aluminum alloy powder, aluminum composite alloy powder, or a mixed powder of these and non-metal particles before solidification. In the gasification method, the powder body is preformed to a specific resistance of 0.2 Ωm or less, and the preformed body is directly induction-heated in a normal pressure atmosphere to raise the temperature rising gradient at 300 above. By increasing the temperature to 400 ° C at 400 ° C while maintaining the temperature at 0.4 ° C / scm or more, the pyrolytic evaporation components can be reduced. It is characterized by reducing the hydrogen content to 1 Oppm or less.

In the present invention, the above induction heating can be performed in an air atmosphere.

Further, in the present invention, after the degassing by the induction heating, the preformed body is cooled in an inert gas atmosphere, so that re-adsorption of moisture can be prevented.

In order to solve the above problems, the present inventors have made various studies, and as a result, the following methods, which are different from the conventional methods, are the most important for achieving the above (A), (B), and (C). It has been found that they are suitable and has led to the present invention.

(i) The powder is heated rapidly as in the past. However, the heating temperature is set to be 30 ° C or more higher than before.

() Regarding the method of solidifying the powder, it is more preferable to use the powder forging method without using the HIP or the extrusion method.

(M) The atmosphere for rapid heating is not a vacuum or inert gas atmosphere as in the past, but an inexpensive stagnant normal pressure atmosphere (stagnant air atmosphere).

(iv) Rapid cooling after powder forging.

That is, the present invention uses an aluminum powder, an aluminum alloy powder, an aluminum composite alloy powder, or a mixed powder of these and non-metal particles in a resistivity of 0.2 Ωcm or less. And pre-formed it directly in a stagnant atmosphere at normal pressure. Heating to raise the temperature gradient above 300 ° C above 0.4 ° CZ sec or more, and at least 30 ° C lower than the vacuum degassing temperature applied when extruding the above powder. By raising the temperature to 400 ° C to 600 ° C, which is a higher temperature by 400 ° C, the hydrogen content is reduced to 1 Oppm or less by removing the pyrolytic evaporation components, and then It is characterized by being solidified by hot working.

Regarding this heating temperature, the melting point of A1 is 660 ° C, but it contains only alloying elements (such as Fe and Ni) that do not lower the melting point of A1. In the case of alloys, it is possible to set the higher temperature to 400 to the melting point.

As a more preferred form of the present invention, a powder forging method is employed as the hot working.

In the present invention, the induction heating can be performed in an inexpensive stagnant atmosphere. In addition, there is no need to carry out vacuum degassing before solidification or plastic working such as extrusion after solidification, and to maintain the characteristics of both strength and toughness without reducing elongation and fracture toughness. Can also be improved.

Furthermore, immediately after the above-mentioned forging, the present invention cools rapidly at a rate of 10 ° C / sec or more, or does not cool down to around room temperature. It is characterized by reheating and quenching solution treatment.

Further, it is particularly preferable that the pre-molding of the powder is performed by applying a wetting agent to the inner wall of a molding die without adding an organic wetting agent to the powder. As It is.

Then, instead of the induction heating, infrared heating or direct current heating can be used.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a SEM micrograph in place of a drawing of the forged body tissue obtained in Example 2-1) of the present invention.

FIG. 2 is a SEM micrograph replacing the drawing of the forged body tissue obtained in Example 2-3) of the present invention.

FIG. 3 is a SEM micrograph as a substitute for the figure of the structural body structure obtained in Comparative Example 2-6).

BEST MODE FOR CARRYING OUT THE INVENTION

Conventionally, since it is difficult to heat the entire embossed body to a uniform temperature in a short time, it is difficult to heat for a long time, usually at least one hour, in a resistance heating furnace. However, as described above, the effect of the high temperature is so long that the rapid cooling effect of the powder is lost. Also, Ri H ₂ 〇 component in the atmosphere prevented the H ₂ 0 elimination reaction, since 0 ₂ Ingredients atmospheric oxidizing the powder, which prevents Surube rather, or in a vacuum, low dew point, during low 0 ₂ concentration atmosphere, heated in an inert gas atmosphere it has been made.

On the other hand, according to the conditions found by the present inventors as a result of earnest studies, the rapid heating of the aluminum powder or aluminum alloy powder compact, which was conventionally considered unsuitable, by the induction heating. Heating is possible, and the removal of adsorbed water and crystallization water is short. Induction heating is sufficient because heating can be performed sufficiently, and the time required for contact with the atmosphere at high temperatures is shortened by shortening the heating time. I can do it.

In other words, in order to increase the electrical contact between the powders, the embossing contact pressure should be increased by about 20% compared to the past, and the direction and frequency of the high frequency magnetic flux should be optimized. And so on.

The aluminum alloy powder used in the present invention is not limited to a rapidly solidified alloy powder, but may be obtained by any method, and its composition is also limited. Instead, it is an aluminum composite alloy powder (a powder in which a nonmetal or an intermetallic compound is dispersed inside aluminum or an aluminum alloy powder). You may. Also, aluminum powder can be used. Furthermore this is found in S i C particles and A 1 ₂ 0 nonmetal particles such as a particle but it may also be one powder der mixed.

First, an aluminum powder, an aluminum alloy powder, an aluminum composite alloy powder, or a powder mixture of these and non-metal particles, having a specific resistance of 0.2 Ωcm The preformed body is increased in density as shown below, but this molding does not use a thermally decomposable organic lubricant and can be performed by a stamping method such as a uniaxial compression method. Or use CIP or other methods. As a result, the powders are subjected to micro shearing force and have metal contact portions with each other.

When the specific resistance exceeds 0.2 Ωcm, it becomes difficult for eddy current to flow. Therefore, the temperature of the preform does not rise easily even when induction heating is performed. If the output of the power supply is increased to increase the temperature quickly, the preformed body having a large resistance value has poor thermal conductivity, so that the temperature difference between the surface of the preformed body and the inside becomes large and the heat is reduced. There are cracks caused by distortion. Resistivity 0. 2 Omega cm will leave less this value is generally achieved at a surface pressure of 4 ~ 6 t 0 n Bruno cm ^2. If it is not achieved within this range, embossing should be performed at high pressure, or after the powder temperature has been increased to reduce the deformation resistance.

Next, this preformed body was directly heated by induction using a power source, so that the heating rate at 300 ° C and above was not less than 400 ° C / sec while the heating rate was 0.4 ° C / sec or more. Heat quickly to 600. The frequency at this time was preferably around 3 kHz in the experiments of the present inventors, but the optimal frequency may be selected according to the object to be heated.

When solidifying a rapidly solidified powder, the internal and surface behaviors are different. In other words, it is mainly the internal state that governs the tensile strength and hardness. Therefore, if the heat history for solidification is reduced, the tensile strength and hardness of the powder itself naturally increase. On the other hand, it is mainly the surface condition of the rapidly solidified powder that governs properties such as the elongation at break and the toughness of the soil.

Aluminum Niu arm alloy on the surface of the powder oxide film = Aluminum Na (A 1 ₂ 0 ₃₎ there is, this is a very stable compound der This film cannot be reduced and removed, and this film prevents the strong bonding between aluminum alloy powders. For this purpose, after solidification, plastic flow processing, such as extrusion or upsetting, is performed to mechanically break this oxide film and to reduce the aluminum content. The method of exposing and binding the newborn has been taken. However, it is conventionally known that even if the extrusion method is used, if the degassing before solidification is insufficient, only a low elongation value and a toughness value can be obtained. . Here we explain degassing o

The surface of the rapidly solidified aluminum alloy powder that has been gas-terminated is covered with an oxide film of 50 to 10 OA, and the surface oxide film is further adsorbed water or crystal water. Contains. This adsorbed water V n B day water causes the elongation and the toughness of the solidified material to decrease.o

These can be removed by heating in the following reaction.

Check out

H 2.0 (1 iq) → H 2 0 (g a s)

A 1 ₂ 0 3

A 1 203-H ₂ 0 + 2 H ₂ 〇 (as

A 1 0 3 ■ H 2 0 →

A 1 2 0 3 + H 2 0 (a s)

The removal reaction occurs above 100 ° C. to 400 ° C., and above 300 ° C., a reaction occurs in which the steam generated by the above reaction directly reacts with the air to release hydrogen. This 9 That is,

2 A) + 3 H ₂ 0 → A 12 03 + 3 H 2 (gas) reaction _σ These methods are used to promote these reactions. The reaction proceeds a lot, heating in vacuum (low pressure makes the reaction more likely to move to the right) and heating in an inert gas with a low dew point (（20 (gas) at a low dew point) The reaction is easier to proceed to the right because there is less). The purpose of this treatment is to suppress the oxidation of powder in an inert gas atmosphere. '

From this point of view, rapid heating is effective to suppress the destruction of the structure inside the powder, but accelerates the desorption of water and crystal water adsorbed on the surface oxide film of the powder. From this point of view, it is clear that it is disadvantageous. In Examples (I) and (2) of Patent II described above in the section of the prior art, it is like this that the tensile strength is improved but the elongation and the fracture toughness are reduced. Presumed to be due to the reason. In Example (3), both the tensile strength and the elongation were improved, but in this example, heating in an inert gas and subsequent vacuum degassing were performed. It is. However, in this example, normal heat treatment (T7) was performed last, and it is assumed that the effect of rapid heating has been reduced by half.

The present inventors have conducted various investigations as a method of achieving sufficient degassing at a low cost even by using rapid heating, and as a result, have solved the problem by using hydrogen gas generated in the above separation reaction. thing Was found. The generation of hydrogen gas occurs particularly at high temperatures. The amount of hydrogen gas generated is about 30 ppm, depending on the heating temperature. The powder compact has about 25% voids, and the volume of hydrogen generated under atmospheric pressure is about 10 times the volume of these voids. In this case, hydrogen is generated to remove the harmful water vapor and oxygen existing in the voids of the green compact and to facilitate the above-mentioned reaction. It is necessary to keep the hydrogen in the green compact void and to inject an inert gas to stir the atmosphere around the green compact. However, in order to generate a large amount of hydrogen at a time, it is necessary to increase the heating at 300 ° C or more, at which hydrogen is generated, to 0.4 sec or more. Furthermore, in order to increase the generation of hydrogen in a series of degassing reactions, it is necessary to heat to as high a temperature as possible. Therefore, the heating temperature is desirably at least 30 ° C or higher than the conventional vacuum degassing temperature (typically heated to about 450 ° C) performed before extrusion. Alternatively, the temperature must be higher than 50 ° C. By doing so, the structure of the powder surface can be easily fixed. As a measure of the ease with which the powder adheres, the residual hydrogen content must be 10 ppm or less.

In addition, when the heating temperature is set to a high temperature, the structure inside the powder tends to become coarser, even if rapid heating is performed, so that (i) short-time heating, (ϋ) short-time solidification (Iii) Rapid cooling after solidification is required. (i) In order to make short-time heating the most advantageous, what needs to be heated must be as small as possible. In this regard, in the extrusion method, since the tip and the remaining part (discard) are cut off, multiple products can be obtained in a single extrusion so as to increase the yield. Due to the use of large green compacts, rapid heating is naturally limited. In the present invention, since one compact is small, rapid heating is possible. In contrast to the green compact used for extrusion, the CIPC Cold Isostatic Pressing) method is generally used, whereas in powder forging, a uniaxially compressed body using a die is used. In this case, when the powder is compressed uniaxially rather than isotropically compressed, the shearing of the powders acts and the contact due to the exposure of the new surface increases. As a result, the induced eddy current becomes larger and the heat generated near the surface of the green compact is transferred to the inside more quickly. Therefore, the forging method is more advantageous in this respect.

C ii) Powder forging is the most effective solidification method for solidification in a short time. The time required for powder forging is about 0.7 seconds, compared to about 5 minutes for extrusion and about 20 minutes for HIP.

(iii) In order to perform rapid cooling after solidification, it is necessary to separate from the applied tool as soon as possible after hot working. Regarding the cooling rate, about 100 ° CZsec can be achieved with water cooling, but fragile materials may cause burning cracks. Such a time Since cooling air should be blown (cooling rate of about 10 to 20 ° C / sec), the cooling rate was set to 10 ° CZsec or more. Also, in some heat-treatable alloys, it is thought that sufficient cooling cannot be achieved only by direct cooling after forging, so a very small heat sink is required. For historical reasons, it is preferable to reheat immediately after forging, rather than reheating after cooling to room temperature. The reheating temperature at this time was specified to be not more than the forging temperature so as not to generate a blister, and to be a forging temperature of 150 ° C. for sufficient solution.

In addition, if plastic working is performed after solidification to reduce the heat history, it is necessary to heat for the plastic working, which is not desirable, so this is not done. Is preferred.

Further, no organic substance lubricant is added, which lowers the thermal conductivity at the time of heating the green compact and prevents rapid temperature rise due to heat of evaporation.

Induction heating is optimal for rapid heating, but radiation heating or direct energization heating is also possible.

The solidified body produced by the method of the present invention contains more non-equilibrium phases than those produced by other methods. At the same temperature as the powder forging temperature, it is easy to change (the structure distribution of the precipitate obtained by X-ray diffraction is easy to change, the shape of the precipitate is easy to change, and the size of the precipitate is coarse) It is easy to use.) In addition, due to hydrogen released from the powder surface, To drive off Murrell atmosphere (Ru mainly Nitrogen Rana), were also extruded or powder forging of a is] ^ 1 ₂ and A r element is detected after being extended heating in an inert gas On the other hand, those solidified by the method of the present invention include only those below the detection limit.

Thus, the surface of the degassed powder obtained by the present invention is in a clean state without crystallization water or adsorption water, and the powder can be forged while being heated. Therefore, after the degassing is completed, this is immediately forged by a known forging method.

However, induction heating has the disadvantage that the temperature of the object to be heated fluctuates as compared with a normal atmosphere heating furnace, so if the temperature difference is large, raise the temperature and then use an atmosphere heating furnace. The temperature can be made uniform by maintaining it at a predetermined temperature. The atmosphere at this time must be an inert gas.

The preformed body thus rapidly heated and degassed is immediately inserted into a mold at about ²⁰⁰ and forged at a surface pressure of 2 to 12 ton Z cm ² .

Example

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto. In the following experimental examples and examples, induction heating was performed at around 3 kHz.

Experiment A

A l-25 S i-2.5 Cu-l M g (weight ratio) Air Ichia DOO microstrip's powder about 2 5 0 g (average particle size of about 5 0 m), and then stamping at a surface pressure of 4 t 0 n / cm ² in diameter 1 0 O mmx height 2 0 mm, After setting the specific resistance to 0.02 Ωcm, the sample was heated up to 500 ° C under the conditions described in A-1) to A-5) below. And cooled by Ar gas flow (at 50 ° C in less than 1 minute), oxygen content, hydrogen content, hardness (mHV), primary Si particles of the powder The diameter was measured. The results are shown in Table 1.

A-1) Atmospheric induction heating (32 ° C sec)

-· · Conditions of the present invention

A-2) Atmospheric induction heating (8.0 ° C / sec)

· · · Conditions of the present invention

A-3) Induction heating in air (4.0 ° C sec)

-Conditions of the invention

A-4) Induction heating in air (0.8 ° C sec)

-Conditions of the invention

A-5) Induction heating in air (0.2 ° C sec)

-·, Out of the conditions of the present invention, and for comparison, the same embossed body as described above was subjected to 500 ° under the conditions described in the following A-6) to A-8) using a resistance heating furnace. Heated to C.

A-6) Resistance furnace heating in vacuum (hold for 1 hour)

· · · Out of conditions of the present invention

A-7) Resistance furnace heating in nitrogen atmosphere (hold for 1 hour) • Out of the conditions of the present invention-8) Atmospheric resistance furnace heating (hold for 1 hour)

Table 1 shows the specific values of each alloy powder obtained above.

Heating oxygen amount Hydrogen amount Powder hardness Primary crystal Si particle size Condition (weight (Pm) (mHv) (urn) A-1 0.27 3 172 3.2 light A-2 0.28 4 153 Article 3.1

Case A-3 0.30 3 130 4.0

A-4 0.28 5 115 7.8 pcs A-5 0.33 6 100 10.2 Description A-6 0.28 3 92 Article 11.2

Case A-7 0.28 9 95 10.7 Outside

A- 8 0.38 17 102 10.0 Note 1: Powder hardness (mHv) is the average of 5 points

Note 2: Primary Si particle size is the average of 30 particles According to the results shown in Table 1, by performing degassing by induction heating according to the present invention, 1) a degassing degree equivalent to that of vacuum degassing can be achieved, and 2) heat history is small. Therefore, it is clear that the structure is not coarse and the hardness is high.

Experiment B

As a raw material powder, a mixed powder containing 30 vol% of SiC particles having an average particle diameter of 1.5 am in an industrial pure aluminum powder (average particle diameter of 50 Lm) which has been air-atomized. Other than that used, the same processing was performed under the conditions of Experimental Examples A-1), A-4), A-5), A-7), and A-8). Table 2 shows the characteristic values of each powder obtained. The powder hardness indicates the result of measuring the aluminum powder.

Experimental Example Heating Oxygen Content Hydrogen Content Powder Hardness Primary Crystal Si Particle Size Condition (Weight (ppm) (mHv) Present Invention B-1 A-1 0.20 4 95 Within Conditions B-2 A-4 0.19 5 93

B-1 3 A-5 0.26 7 85

The present invention

B-4 A-7 0.21 8 63

Out of condition

B-5 A-8 0.32 15 62 Note 1: Powder hardness (mHv) is the average of 5 points

Experimental example C

As the raw material powder Eaa preparative My's been A 1 one 2 0 _{S i} - containing 2 N i alloy powder Aluminum Na powder (average particle diameter 5 0 zm) to an average particle size of 0. 5 - 5 F e Except for using the mixed powder, the same treatment was performed under the conditions of Experimental Examples A-1), A-4), A-5), A-7) A-8). Table 3 shows the characteristic values of the obtained powders. The amount of oxygen indicates the amount obtained by removing the amount of oxygen contained in the alumina particles by calculation. The powder hardness shows the result of measurement of aluminum alloy powder. '

Recitation Heating oxygen content Hydrogen content Powder hardness Primary crystal Si particle size Condition (wt%) (ppm) (mHv) (m) Present invention C-1 A-1 0.26 4 186 2.6 Within condition C-2 A-4 0.29 3 179 2.4

C-1 3 A-5 0.32 5 145 5.6 The present invention

C-1 4 A- 7 0.28 10 108 6.8 Out of condition

C-5A-1 8 0.40 19 113 6.5 Note 1: Powder hardness (mHv) is the average of 5 points

Note 2: Primary Si particle size is the average of 30 particles

Experimental example D

A 1 — 20 S i — 5 Fe e-IN i About 500 g of air atomized powder (average particle size 50 fi m) of composition, and the embossing density is shown in Table 4. In this way, the mold is pressed to a diameter of 10 Omm and a height of 40 mm, the specific resistance is measured, and a thermocouple for measuring the temperature is provided at the center and the outer periphery of the stamped body. One hole with a diameter of Φ1.0 inm was drilled, and the temperature gradient was determined so that the temperature could be raised most quickly without the temperature difference between the two reaching 70 ° C or more.

As shown in Table 4, when the specific resistance is about 0.2 Qcm or more, the heating efficiency is poor.

Example 1

A l-25 S i-2.5 Cu-l Mg (total weight ratio) composition of air-atomized powder (average particle size of about 50 pim) with a diameter of 10 O mmx The mold was embossed to a height of 4 Omm and a specific resistance of 0.02 Ωcm, and the temperature was raised from room temperature to 500 ° C in air for 4 minutes by induction heating, and heating was performed. The Re this immediately, was inserted into the graphite lubricated conducted mold (2 0 0 ° C) in, and powder forged at a surface pressure of 8 t 0 n Z cm ^2, soaked in water at room temperature to immediately after forging Cooling. This was 4曰between natural aging, lock © et le hardness B scale (H _R B) This and was measured by filtration and Tsu H _R B 8 6 der.

For comparison, a molded body prepared in the same manner as in Example 1 was heated in a resistance heating furnace at 500 ° C. for 1 hour in a nitrogen atmosphere, and forged and cooled in the same manner as in Example 1 after the completion of heating. , the self effect cure, the Tsu this filtration, H _R B 7 9 der and the hardness was measured (Comparative example 1).

Example 2

A 1 one 2 5 S i - 2. 5 C u - l M g Eaa preparative Mai's powder 2 5 0 g of composition (average particle size of about 5 0 am), the surface pressure 4 ton Z cm ² in diameter 1 0 After embossing to an O mmx height of 2 O mm and setting the specific resistance to 0.02 Qcm, heat the sample to 50,000 under the conditions described in the following 2-1) to 2-5). heating At the time when the heating was completed: The pressed product was inserted into a mold heated to 200 ° C., the powder was forged at a surface pressure of 8 ton / cm ² , and immediately after forging, was cooled by immersing in water. After that, natural self-efficacy took place for four days.

In the case of humidification in 2-3 '), the embossed body is heated to 40% before degassing and exposed to an atmosphere of 90% humidity for 24-hours. As a result, a large amount of adsorbed water was made to adhere to the powder surface, and then the steps after heating and degassing were performed in the same manner.

2 — 1) Induction heating in the atmosphere (32 .C sec)

The present invention conditions

2-2) Induction heating in the atmosphere (sec at 8.0)

The present invention conditions

2 — 3) Atmospheric induction heating (.0 ° C sec)

The present invention conditions

2-3 Atmospheric induction heating (4.0 ° C sec)

Humidification

2 4) Atmospheric induction heating (0.8 ° C sec)

The present invention conditions

2-5) Atmospheric induction heating (0.2 C sec)

• Out of the conditions of the present invention, and for comparison, the same stamping body as above was heated to 500 ° C under the conditions described in 2-6) to 2-7) below using a resistance heating furnace. Forging by heating at, then 2 at 485 After heating for a while, it was immersed in water to form a solution, followed by a 4 day natural self-efficacy.

2 — 6) Resistance furnace heating in nitrogen atmosphere (hold for 1 hour)

• Not in accordance with the present invention 2-6 ') Heating in resistance furnace in nitrogen atmosphere (hold for 1 hour) Humidification is not applicable.

2-7) Atmospheric resistance furnace heating (hold for 1 hour)

• Out of condition of the present invention 2 — 7 ') Atmospheric resistance furnace heating (hold for 1 hour)

Humidification is out of the conditions of the present invention. Table 5 shows various specific values of the alloy powder carcasses obtained above.

Degassing conditions Characteristics of forged body

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2-2 Induction heating Atmosphere 8.0. C / sec Temperature rise None 0.30 4 50 2.0 85 Application 2-3 Induction heating Atmosphere 4.0 ° C / sec Temperature rise None 0.29 3 52 3.0 86

2-3 'Induction heating Atmosphere 4. (TC / sec temperature rise 0.76 4 51 1.8 88 Example

2-4 Induction heating Atmosphere 8.0 ° C / sec Temperature rise None 0.32 5 50 1.8 85

2-5 Induction heating Atmosphere 0.2 ° C / sec Heating None 0.38 8 45 1.0 83 Ratio

2 1 6 Resistance furnace heating Hold in nitrogen atmosphere for 1 hour None 0.28 9 49 1.8 87

2-6 'Resistance furnace heating Nitrogen atmosphere 1 hour hold Yes 0.38 11 32 0.2 82

2-7 Resistance furnace heating Atmosphere in air Hold for 1 hour None 0.42 17 30 0.0 75 Example

2-7 'Resistance furnace heating Atmosphere Hold for 1 hour Yes 0.93 23 23 0.0 65

From the results in Table 5, it can be seen that, according to the present invention, good degassing was achieved and the heat history was small, so that the rapid cooling effect of the raw material powder was not impaired and various properties such as hardness, tensile strength and elongation were obtained. This shows that a well-balanced forged body was obtained.

In addition, when the results of 2-3 ′) and 2-6 ′) are examined, it is clear that a large amount of adsorbed water (this is The dewatering (desorption water) is sufficient even if there is water for crystallization of aluminum in the forged part), so the properties of the forged body are good, but the conventional degassing method of 2-6 ') It is clear that the properties of the obtained forged body are bad because it is difficult to remove such a large amount of adsorbed water.

The forged bodies obtained in Examples 2-1) and 2-3) according to the present invention described above and Comparative Example 2-6) according to the conventional method are cut, polished, and strongly etched. After that, the tissue was observed by SEM (scanning electron microscope). Figures 1 to 3 show SEM photographs of each forged body structure. It can be seen that the structure of the forged body according to the present invention is clearly finer than the conventional product. Example 3

Atomized A 1 — 2 OS i-5 Fe-2 N i (average particle diameter 50 m) A mixed powder containing aluminum powder with an average particle diameter of 0.5 m in the alloy powder. Except that the powder was used, the same procedures were performed as in Experimental Examples 2-1), 2-4), Comparative Examples 2-6) and 2-7), and the forged bodies 3-1) and 3-2) of the present invention were used. And 3-3) and 3-4). Same as Example 2 Table 6 shows the characteristic values measured in the same manner. Note that the oxygen content indicates a value obtained by excluding the oxygen content contained in the alumina particles by calculation.

The results in Table 6 show that the forged body according to the present invention has good various properties.

Example 4

Air-atomized A 1 — 12 Si — 5% by volume (average particle size 2 m) Aluminum complex alloy powder of SiC (average particle size 50 m) Except that the raw material powder was used, the procedure was the same as in Experimental Examples 2-1), 2-4) and Comparative Examples 2-6), 2-7), and the forged bodies 4-1), 4-2) of the present invention were used. And 4-4) and 4-4). Table 2 shows each characteristic value measured in the same manner as in Example 2.

7

The results in Table 7 show that the forged body according to the present invention has good various properties.

Example 5

A 1-25 S i -2.5 Cu-1 Mg composition air — atomized powder approx. 250 g (average particle size approx. 50 um), surface pressure 4 t0 n / cm ² embossing and the diameter 1 0 0 mm冋2 0 mm, the after the resistivity 0. 0 2 Omega cm, the following 5 - 1) to each condition you described 5 one 5) 5 0 0 ° was heated at C until, inserted into a mold heated to 2 0 0 ° C when the pressurizing heat has ended, perform the powder forged at a surface pressure of 8 ton / cm ^2, cooling dipped in water immediately after the completion 4 After that, natural self-efficacy was carried out for 4 hours 5 1 1) Atmospheric induction heating (32 ° C / sec)

—— · Necessary conditions for invention

5-2) Induction heating in air (8.0 ° C / sec)

—— · * Invention conditions

3) Induction heating in air (4.0 ° C / sec)

• Conditions of the invention

4) Atmospheric induction heating (0.8 ° C / S e c)

-Conditions of the invention

5-5) Induction heating in air (0.2 ° C Z sec)

• Out of the conditions of the present invention, and for comparison, the same stamping body as described above was heated to 500 ° C under the conditions described in the following 5-6) to 5-7) using a resistance heating furnace. To make the curtain and then at 485 ° C for 2 hours After heating for a while, it was immersed in water to form a solution, and then self-efficient for 4 days.

5 — 6) Resistance furnace heating in nitrogen atmosphere (I time holding)

• Out of the conditions of the present invention 5-7) Atmospheric resistance furnace heating (hold for 1 hour)

• Out of the conditions of the present invention 5-8) Aging in resistance furnace in vacuum (Hold for 1 hour)

Table 3 shows the specific values of each alloy powder obtained above. table

According to the results of Fig. 8, the aluminum alloy powder forging according to the present invention has good degassing and small heat history, so that the rapid cooling effect of the raw material powder is not impaired, and the hardness and tensile strength are not impaired. It can be seen that a forged body with good balance of properties such as strength and elongation was obtained.

Example 6

A l - 2 0 S i - 5 F e - 4 C u - l at M g (% by weight) A Tomai's powder pressing force 4 the composition of ton / cm ^2, Φ Ri by the die wall lubrication molding 5 It was formed into a shape of 0 mm X 5 O mmt, heated by induction heating to the forging temperature in 4 minutes, and forged into a φ53 mm shape. The forging conditions were a heating temperature of 500 and a forging pressure of 5 ton Z cm ² .

After forging, T6 heat treatment (held for 1.5 hours at 490, put into water, and aged for 6 hours at 180) was performed to evaluate the strength. This and the tensile strength was evaluated at n = 2 ^{filtrate, 5 3 kg / mm 2.} 5 1 kg / mm was ² Tsu Der.

For comparison, when the powder was forged by conventional lubricant mixing and electric furnace heating, the tensile strength was 48 kg Zmm ² at n = 2.

From these results, it can be seen that better results can be obtained by applying the lubricant to the inner wall of the die and preforming without mixing the lubricant into the raw material powder.

In the above embodiments, the rapidly solidified powder is described as an example. However, the method of the present invention is effective for reducing the cost by applying the method to degassing of powders other than the rapidly solidified powder.

Example 7

Three gas atomized powders (A l-7.3 Ni-2.9 Fe) were pressed into a Φ 70 mm X 25 mm t with a surface pressure of 4 ton Z cm ² , and pressed for 5 minutes in 2 minutes. Up to one is induction heating and one is Radiation heating and one for direct current heating were forged to 0.72 mm. Forging surface pressure 8 t 0 n / cm ^2. After forging, it was water-cooled.

Tensile strength 6 2. 3 kg / mm ² at room temperature for induction heating products, elongation 1 3. 5%, K 1 C 2 8. O kg / mm 2 ^ m.

Tensile at room temperature radiant heating products strength 6 0. 1 kg / mm ^2, elongation 1 3.0%

Tensile strength of directly heated product at room temperature 63.4 kg / mm elongation 13.6%

Example 8

Gasua DOO Mai's powder (A 1 - 8. 8 F e - 3. 7 C e) was embossed with a surface pressure of 4 ton / cm ² to 0 7 0 mm X 2 5 mmt , 1. 5 minutes 5 5 Induction heating up to 0 ° C. Forged to 0.72 mm. Forging surface pressure was 8 t 0 n / cm ^2. After forging, water cooled

Tensile strength at 65.2 kg Z mm elongation 16.2% Example 9

Gas atomized powder (Al-8Zn-2.5Mg-1

C υ - 1. 6 C o) a ø 7 0 mmx 2 5 was embossed at a surface pressure of 4 ton / cm ² to mmt, were forged to 7 2 mm induced pressurized heat for 1 minute at 5 3 0 ° C or .锻 The surface pressure was 8 ton / cm ² . After forging, the temperature had dropped to 460 ° C, so it was cooled down to 50 ° C in 1 minute by induction heating, then water-cooled, and after 4 natural aging characteristics investigated.

Tensile strength at room temperature 70.2 kg Z mm ² , elongation 12.5% Example I 0

A1-25Si13Cu-lMg Air with composition of atomized powder, 10 g of 10 g into 10 X 18 x 3 O mm with a surface pressure of 4 ton Z cm ² did. This was heated in a stagnant atmosphere by infrared induction heating to 510 for 4 minutes and then forged. The mold temperature was 400 ° C., and a mold of I0.5 × 10.5 mm was used. Forging surface pressure was 8 t 0 n / cm ^2. After forging, it was water-cooled. The characteristics were investigated without heat treatment.

Tensile strength at room temperature 58 kg / mm ² , elongation at break 3. '0%. The same compact was heated in a nitrogen stream (7 liters Z) to 510 for 4 minutes and then forged. The conditions were the same as above.

Tensile strength at room temperature 51 kg / mm ² , elongation at break 2.1%. Example 1 1

A 1-17 S i — 5 Fe — 3 Cu — l M g Air atomized powder with a composition of 20 mg, CIP (contact pressure 2 ton / cm ² ) ø180 x 3 A green compact of 00 mm was produced.

This is heated in an atmosphere of nitrogen (450 ° C x 4 hours).

(490 ° C x 4 hours) ②Induction heating in air (16 minutes to 450 ° C)

(The temperature rises to 500 ° C over 16 minutes)

These are extruded to 044 with a 0200 container (extrusion ratio 2 1) Molded. Immediately after the extrusion, the material was cooled and the properties of the F material were adjusted. After that, T6 treatment (470 ° CX for 2 hours → water-cooling 175 ° CX for 6 hours) was performed to investigate the properties.

After the extrusion, it was placed in a furnace at 485 ° C for 10 minutes, cooled with water, then aged at 175 ° C for 6 hours, reheated, and reheated to obtain T6 material. It shall be.

③ Similarly, press 250 g of powder to ø8 O mm

(Mold wall lubrication: surface pressure: 4 ton Z cm ² ), induction heating in the air (temperature rise to 500 ° C over 2.5 minutes), and this is done with ø82 metal. The powder was forged in a mold at a surface pressure of 8 ton / cm ² . It was water-cooled immediately after forging. Use this as F material 0

After forging Induction heating up to 485 for 1 minute and water cooling

Rapidly reheat T 6 material after aging treatment at 1 75 ° C for 6 hours o

After forging, put it in a furnace at 485 ° C for 10 minutes, water-cool it, and then reheat it after aging at 1775 ° C for 6 hours.

Immediately after forging, water-cooled, T6 treated (ie, treated with ⁴⁸⁵ eCX for 2 hours, then water-cooled, and treated with X175 for 17 hours) is used as T6 material. You.

Table 9 shows the results of an investigation of the characteristics of each of the above samples. Table 9

Note) The numbers in ① to ③ attached to the head of the solidified material in the table indicate ① in the text in Example 11 1.

Corresponds to the processing of (3). From the above results, the following can be understood.

(1) It is effective to use the rapid heating method of the present invention in extrusion.

(2) In extrusion, the material heated rapidly to a low temperature does not elongate.

(3) Extrusion heated rapidly to a low temperature has a large residual hydrogen content.

(4) In the case of the rapid heating extrusion of the present invention, the characteristics are better when reheating T 6 is performed than when performing normal T 6.

(5) Sufficient properties can be obtained with the F material for the rapid heating powder forging of the present invention.

(6) The T6 material that has been subjected to the rapid heating powder forging according to the present invention has properties that are similar to those of the reheated T6 material, and of the reheated T6 material more than the reheated T6 material. You can see good things.

(7) It can be seen that the product of the present invention improves both tensile strength and breaking elongation simultaneously with the conventional material.

Example 1 2

The tensile strength and elongation at 300 ° C of the above two materials and the eleven materials were examined.

2 material ^{• • • SS kg Zm m 2} 3. Ni would Yo 5% elongation Comparative Example 1 1 material · '· 2 8 1ς Ε Ζιη πι 2 5, 6% elongation present invention this, the product of the present invention heat It can be seen that the properties are also excellent.

Example 13 A 18 F e — Rotating disk atomized powder having a composition of 4 Mo, 25 Qg is pressed into φ8 O mm (mold wall lubrication: surface pressure 4 ton Z cm ² )

Induction heating in air (temperature rises over 5 minutes by 1.0 minutes)

(The temperature rises over 1.0 minute by 65 0)

And powder forging at a surface pressure of 8 ton / cm ² take this into mold ø 8 2 mm.

Immediately after forging, it was cooled with water and its properties were investigated. Table 10 shows the obtained results.

Table 10

As described above, in the case of aluminum alloys having a high melting point, heating to a temperature exceeding 600 in some cases is favorable.

Industrial applicability

As described above, according to the present invention, it is possible to perform sufficient degassing with a low heat history at a low cost with a simpler process than before. All of the tensile strength, elongation, and fracture toughness values can be improved without heating in an inert atmosphere, vacuum degassing, or plastic deformation after solidification. This is an effective method.

Claims

The scope of the claims

The aluminum powder, anoluminium alloy powder, aluminum composite alloy powder, or a powder mixture of these and non-metal particles is preformed to a specific resistance of 0.2 Ωcm or less. The preform is directly induction heated in a normal pressure atmosphere, and the temperature is raised to 400 DC to 600 ° C while maintaining the temperature rising gradient at 300 ° C or more at 0.4 / scm or more. A degassing method for aluminum alloy powder characterized by removing pyrolytic evaporation components and reducing the hydrogen content to 1 Oppm or less.

2. The method for degassing an aluminum alloy powder according to claim 1, wherein the induction heating is performed in an air atmosphere.

The method according to claim 1 or 2, wherein after the degassing by the induction heating, the preformed body is cooled in an inert gas atmosphere to prevent re-adsorption of moisture. 3. The method for degassing an aluminum alloy powder according to item 2. Aluminum powder, aluminum alloy powder, aluminum composite alloy powder or a mixed powder of these and non-metal particles is preformed to a specific resistance of 0.2 Ωcm or less, and the preformed body is formed. Is directly heated in a stagnant atmosphere at normal pressure to raise the temperature gradient at 300 ° C or more to 0.4 ec or more. At least 30. C Eliminates thermally decomposable evaporation components by raising the temperature to a high temperature of 400 ° C to 600 ° C A method for solidifying rapidly quenched aluminum alloy powder, characterized by immediately solidifying by hot working after the hydrogen content is reduced to 1 Oppm or less.

5. The method for solidifying a rapidly quenched aluminum alloy powder according to claim 4, wherein the temperature raised by the induction heating is from 400 to the melting point.

The method for solidifying a rapidly quenched aluminum alloy powder according to any one of claims 4 and 5, wherein the hot working is powder forging. .

5. The method for solidifying rapidly cooled aluminum alloy powder according to claim 4, wherein the induction heating is performed in a stagnant atmosphere.

Immediately after the above forging, cool rapidly at a speed of 10 sec or more, or cool to near room temperature, and reheat to a forging temperature of -50 or less forging temperature. The method for solidifying a quenched aluminum alloy powder according to any one of claims 4 and 5, wherein the solidification treatment is performed.

Claims 4 to 6 wherein the preforming of the powder is performed by applying a wetting agent to the inner wall of a molding die without adding an organic wetting agent to the powder. The solidification method of the quenched aluminum alloy powder according to any one of the paragraphs. 0. Claims 4 to 7 in which radiant heating or direct current heating is used instead of the induction heating described above. The solidification method of the quenched aluminum alloy powder according to any one of the above items.