JPH07316601A - Production of rapidly solidified aluminum powder and aluminum alloy compact - Google Patents

Abstract

PURPOSE:To meet the recent demand for weight reduction required of automotive parts, etc., by specifying the composition of a rapidly solidified Al alloy powder, subjecting this alloy powder to hot compaction and to aging treatment, and improving strength. CONSTITUTION:An Al alloy powder, having a basic composition consisting of, by weight, 5-11% Zn, 2-4.5% Mg, 0.5-2% Cu, 0.01-0.5% Ag, and the balance essentially Al, is used. It is preferable to incorporate 2-6% Mn and further 0.01-2.0% of at least one element selected from among Co, Cr, Ni, Zr, and Ti into the composition. Moreover, it is preferable to incorporate Si and/or Ca by <=1%. A rapidly solidified powder of this alloy is hot-compacted in the air, in vacuum, or in an inert gas and then aged. Further, the tensile strength of a compact after T6 treatment is about (80 to 90)kgf/mm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy molded material suitable as an aircraft material, an automobile part material, a precision machine part material, an electronic material, a spring material, a screw material and the like. Such an aluminum alloy molded material is particularly suitable as a material for automobile parts and the like, which has recently been desired to be reduced in weight.

[0002]

2. Description of the Related Art One example of a high-strength Al alloy is described in Japanese Patent Laid-Open No. 63-83251. The invention disclosed in this publication is based on the Al-Zn-Mg-Cu system.
n, Cr, B, Be, Ni, Co, Zr, Hf and A
An alloy having a composition to which at least one of g is added is obtained by a casting method, subjected to melt casting plastic working, and then subjected to solution heat treatment and aging treatment under appropriate conditions to obtain a tensile strength of 66.4 kg / This is an Al alloy having a very high mm ² and an excellent elastic modulus. The obtained Al alloy is
It is said to be suitable as a non-ferrous metal spring material used in electronic machinery terminal machines and precision machine parts. However, this publication does not teach anything about materials by powder metallurgy.

[0003]

High strength lightweight non-ferrous materials are widely used for automobile parts, terminal machines for electronic materials, precision machine parts and the like, which have recently been required to be reduced in weight. Particularly for automobiles, Al alloys have gradually been used in place of steel in many parts. However, although the mechanical properties of Al alloys have been dramatically improved in recent years, they are still insufficient compared with high-strength steels, and their use is also limited. For example, so-called A widely used as a high-strength Al alloy
Even the 7000 series has insufficient strength and its range of use is limited.

Therefore, the main object of the present invention is to further improve the mechanical properties of the Al alloy in order to further expand its applications.

[0005]

The present inventor has conducted various studies in view of the problems of the prior art as described above, and as a result, Al-Zn-Mg-Cu-based alloy ( A so-called A7000 series aluminum alloy) composition is mixed with a specific amount of Ag, and a rapidly solidified alloy powder is prepared by an atomizing method, and the alloy powder is used to obtain a solidified compact by a powder metallurgy method. It was found that the tensile strength of the molded material after T6 dramatically increases when the material is age-hardened under appropriate conditions.

Further, it has been found that when a specific transition metal element is blended with an Al alloy having such a composition, an Al alloy having a strength as high as never before has been obtained.

The present invention has been completed based on the above findings, and provides the following method for producing an aluminum rapidly solidified powder and an aluminum alloy molded material; Zn5-11%, Mg2-4.5%, Cu0.5-
An Al alloy rapidly solidified powder containing 2% and 0.01 to 0.5% Ag, and the balance substantially consisting of Al.

2. Item 2. The Al alloy rapidly solidified powder according to Item 1, further containing 2 to 6% of Mn.

3. Item 3. The Al alloy rapidly solidified powder according to Item 1 or 2, further containing 0.01 to 2.0% of at least one element selected from Co, Cr, Ni, Zr, and Ti.

4. Item 4. The Al alloy rapidly solidified powder according to any one of Items 1 to 3, further containing Si and / or Ca in a range of up to 1%.

5. A according to any one of items 1 to 4 above
1. A method for producing an aluminum alloy molded material, characterized by hot-solidifying an alloy rapidly solidified powder in air, in a vacuum or in an inert gas atmosphere, and then subjecting the resulting molded body to an aging treatment to increase the strength. .

In the present specification, "%" means "% by weight".

In the present invention, Zn 5 to 11%, Mg
2 to 4.5%, Cu 0.5 to 2% and Ag 0.01 to
A having a composition containing 0.5% and the balance substantially consisting of Al
An Al alloy rapidly solidified powder is obtained by atomizing the molten metal of the l-based alloy. As a matter of course, such an Al-based alloy may contain inevitable impurities (Fe, Si, etc.) in an amount that is contained in a normal Al alloy. As the atomizing method, any method such as an air atomizing method, an inert gas atomizing method using Ar or He, or an N ₂ gas atomizing method can be adopted. Upon atomizing, the molten Al-based alloy is solidified at a cooling rate of 10 ² K / sec or more.

The above Al alloy powder is classified to 150 μm or less, the classified powder is subjected to cold compression molding, and the powder is heated in air, more preferably in an inert gas or most preferably in vacuum, and heated. A molded product is obtained by performing inter-extrusion molding. Then, after subjecting the obtained molded body to solution treatment,
By aging treatment, a high-strength aluminum alloy molded material can be obtained.

The reasons for defining the additive elements in the Al alloy of the present invention are as follows.

In general, 7090 alloy (Zn:
7.3 to 8.7%, Mg: 2.0 to 3.0%, Cu:
0.6 to 1.3%, Co: 1.0 to 1.9%) is known as a high strength and high elasticity Al alloy. In the alloy of this system, a fine dispersed phase called GP zone or intermediate precipitation phase is formed after the T6 treatment, which contributes to the improvement of strength. The main chemical constituents of this dispersed phase are MgZn ₂ , M
It is considered to be composed of g ₃₂ (AlZn) ₄₉ or the like. Since the strength of the Al-Zn-Mg-Cu alloy is improved by such age precipitation hardening by the dispersed phase, it is important to increase the density of these fine dispersed phases in order to further improve the tensile strength. .

As one of the methods, by quenching and solidifying an Al alloy, crystallization and segregation of additive elements such as Zn, Mg, and Cu are suppressed, a solid solution is formed in Al as much as possible, and aged precipitation after T6. There is a method of increasing the volume fraction of the phase. As a specific means for rapidly solidifying the molten Al alloy, there is, for example, an atomizing method. By adopting such a method, the solid solution range of the additional element can be greatly expanded to the high concentration side. However, even if such a rapid solidification method is adopted, there is a limit to the expansion of the range of addition of the additional element in the Al alloy. In other words, Zn, Mn, Cu
If the added amount of such elements is too large, even after rapid solidification, these additional elements cannot form a solid solution in Al, thus forming coarse crystallized substances and causing a decrease in strength of the Al alloy. Is not preferable. On the other hand, when the amount of the added element is too small, the volume fraction of the fine precipitation phase in the GP zone or the like decreases, so that the contribution to the strength improvement of the Al alloy due to the dispersed precipitation decreases. Therefore, in the present invention, the addition amount in the Al alloy is set to Zn 5 to 11%, Mg 2 to 4.5%, and Cu 0.5 to 2%.

In the present invention, Zn 5 to 11%, Mg
In addition to the Al alloy containing 2 to 4.5% and Cu 0.5 to 2%, Ag 0.01 to 0.5% (more preferably,
0.01 to 0.1%) is essential. The compounding of Ag remarkably improves the strength after T6 of the material molded from the Al alloy rapidly solidified powder. For example, Al
In the alloy composition of -9Zn-3Mg-1.5Cu-4Mn, the maximum tensile strength is exhibited when the Ag content is only 0.02%. Regarding the effect of adding Ag,
It is also described in JP-A-63-83251.
However, this publication describes Al-5.9Zn-2.7.
Mg-0.5Cu-0.13Mn-0.4Zr-0.1
It is said that the most excellent mechanical properties are obtained when 1.0% of Ag is added to an Al alloy having a very limited composition of 5Cr-0.1Ni-0.02Be-0.01B. From this, it is assumed that there is an essential difference between the action of Ag in the Al alloy described in this publication and the action of Ag in the Al alloy of the present invention.

In the present invention, the above Al-Zn-M is used.
By further adding 2 to 6% of Mn to the g-Cu-Ag composition (hereinafter, sometimes simply referred to as a basic composition), the crystal grain size is made finer and dislocations caused by the formation of the intermetallic compound Al ₆ Mn. The effects such as work hardening due to the increase in density are achieved, and the tensile strength of the molded material is improved. Further, it has been confirmed that the intermetallic compound is formed in a slender plate shape along the extrusion direction, and this also functions as a fibrous reinforcing material. If the amount of Mn is less than 2%, the effect of refining the crystal grains becomes insufficient, while if it exceeds 5%, coarse precipitates of Al ₆ Mn are formed, which is not preferable.

In the present invention, one or more elements selected from Zr, Co, Ni and Cr are added to the above basic composition in the range of 0.01 to 1%. The tensile strength of the Al molded material can be further improved. When the addition amount of these is less than 0.01%, the improvement of the effect due to the addition is not sufficient, while when it exceeds 1%, the formation of coarse precipitates causes rather a decrease in strength. .

Furthermore, with respect to the above basic composition, Si
It is also possible to form a phase of Mg ₂ Si or the like in the alloy and to achieve the dispersion precipitation strengthening by these phases by adding.

When Ca is added to the above basic composition, it is incorporated into the GP zone to increase the strain in the zone, thereby increasing the tensile strength.

The Al alloy rapidly solidified powder according to the present invention is not particularly limited in terms of manufacturing method, and can be manufactured by any conventional method. For example, an Al alloy having the composition according to the present invention is melted in a high frequency melting furnace to obtain 850
After holding at a temperature of up to 1000 ° C, the molten Al alloy is poured into the crucible attached to the atomizing machine. There is a hole in the bottom of this crucible so that it can be led to the molten metal ejection port of the atomizing nozzle without lowering the temperature of the molten metal. Immediately before the molten aluminum alloy reaches the atomized nozzle molten metal jet, high-pressure atomizing gas such as air, nitrogen, Ar, or He jets out from the nozzle hole, and the pressure of this gas causes it to come out from the molten metal jet. The molten aluminum alloy is finely crushed. The molten metal finely pulverized in this way is generated by the high pressure gas and / or the atmosphere.
Immediately cooled and solidified, an Al alloy rapidly solidified powder is obtained. The powder thus obtained can be sieved to have a predetermined particle size (for example, 150 μm or less with a 100-mesh sieve) depending on the application.

Further, the Al alloy molded material according to the present invention can be manufactured by any conventional method without any limitation. For example, the rapidly solidified powder obtained as described above is degassed if necessary, and then subjected to arbitrary cold working, for example, cold isostatic pressing (CIP), to a predetermined surface pressure (for example, 3000 kg / cm ² ). A powder compact is prepared with to obtain a billet for hot extrusion. Next, such a billet is heated in an Ar atmosphere at, for example, about 400 to 500 ° C., and is extruded by any molding method, for example, hot isostatic pressing (HIP), or extrusion at an extrusion ratio of about 5 to 20. A molding material can be obtained by the method. The formed material thus obtained may be further subjected to predetermined processing such as forging. Alternatively, after degassing the Al alloy rapidly solidified powder obtained as described above, if necessary,
Powder forging may be performed to obtain a molded product, or such a molded product may be further subjected to predetermined processing.

By finally aging the molded body thus obtained, a high-strength aluminum alloy molded material can be obtained.

[0026]

The molding material obtained by using the Al alloy rapidly solidified powder according to the present invention has excellent mechanical properties such as tensile strength. Therefore, it is useful as a material for aircraft parts, a material for automobile parts, a material for precision machine parts, an electronic material, a material for springs, a material for screws, etc., which need to be lightweight and have high strength.

[0027]

EXAMPLES Examples will be shown below to further clarify the features of the present invention.

Example 1 100 kg of molten Al alloy containing raw material components other than Ag
After making, divide it into about 20 kg of molten metal, add different amounts of Ag to each, and make Al with the specified alloy composition.
Prepared a bullion. Next, the prepared metal was melted by a high-frequency melting furnace attached to an atomizer and was made into a rapidly solidified powder by an air atomizing method.

Table 1 below shows the composition of the Al alloy rapidly solidified powder thus produced.

For the sake of comparison, Table 1 also shows the compositions of the Al alloy containing no Ag (Sample No. 10) and the Al alloy containing 1% or more of Ag (Sample Nos. 11 to 13). .

[0031]

[Table 1]

Further, the above sample No. About 5 kg of the ingots 1 and 2 were cut out, each was melted in an Ar (argon) atmosphere, and an Al rapidly solidified powder was obtained by an Ar atomizing method using pure Ar. This Ar atomization method was performed in order to produce a powder having a significantly reduced oxygen content.

The obtained powder was classified to 150 μm or less by sieving, and 100 g of this powder was pressed with a cold isostatic press at a surface pressure of 3000 kg / cm ² to obtain a powder compact with a diameter of about 30 mm and a length of about 70 mm. A body was prepared and used as a billet for hot extrusion.

This billet was inserted into a container (internal diameter 32 mm) of an extrusion molding machine having a maximum load of 100 tons to obtain a bar having a diameter of 10 mm (extrusion ratio 10). During extrusion, the billet should be kept in an Ar atmosphere at 500 to prevent oxidation.
Heated at 0 ° C x 30 minutes, immediately inserted into a heated container and extruded in air.

From the extruded rod thus obtained, a tensile test piece having a parallel portion having a diameter of 4.4 mm and a length of 25 mm was obtained, and the test piece was heated at 490 ° C. for 2 hours for homogenization treatment and quenching. Then, soak in an oil bath heated to 120 ° C for 2
It was aged for 4 hours (T6 treatment) and then subjected to a tensile test.

Table 2 shows the tensile strength of each Al-based alloy molded material.

[0037]

[Table 2]

Note 1: "I" indicates the result when the powder produced by the air atomizing method is used, and "II" indicates the case where the powder produced by the Ar atomizing method is used. The result about is shown.

Note 2: In evaluation, "○" means that
It is shown that the tensile strength was increased by carrying out the method of the present invention.

From the results shown in Table 2, it can be seen that in the composition shown here, the alloy having an Ag content of 0.04% exhibits the highest strength. Also, this alloy (Sample No. 1)
Has a strength of about 3.2 kg compared to an alloy containing no Ag.
It can be seen that f / mm ² increases.

Further, in the case of the comparative examples (Sample Nos. 11 to 13) in which the added amount of Ag was increased, the strength was decreased as the added amount was increased. In particular, the strength when the amount of Ag is 1.8% is lower than the strength when Ag is not added.

From the above results, the addition amount of Ag was 0.0
It is preferably 1 to 0.1%, and 0.01% to 0.
It is clear that it is more preferable to be 05%.

When a material prepared by the Ar atomizing method in an Ar atmosphere is used, the tensile strength is 84.2.
A material of kgf / mm ² has been obtained, and it is clear that the tensile strength is improved by reducing the oxygen content.

Regarding the Zn content, Sample No. As is clear from the results of 5 and 7, it is desirable that the content is in the range of 5 to 11%, and if it is out of this range, the tensile strength is significantly reduced.

Regarding the content of Mg, the sample No. As is clear from the results of 8 and 9, it is desirable that the content is in the range of 2 to 4.5%, and if it is out of this range, the tensile strength is significantly reduced.

Regarding the Cu content, Sample No. 6,
As is clear from the results of 14 and 15, 0.5-2
It is desirable to be within the range of%, and if it deviates from this range, the tensile strength is remarkably lowered.

Example 2 The Al alloy of Example 2 is basically the alloy composition of Example 1 to which Mn of 4 to 6% is added.

Table 3 shows the chemical composition of each alloy.
Table 4 shows the results of the tensile test. The powder preparation by the Ar atomizing method, the T6 treatment conditions and the tensile test method are as follows.
Same as in the first embodiment.

[0049]

[Table 3]

[0050]

[Table 4]

In the case of hot extrusion in the presence of Ar, Ag
The strength of the molded product obtained by adding 0.02% and the extrusion ratio of 10 was highest at 90.4 kgf / mm ² (Sample No. 16), and the sample No. containing no Ag was added. 10k compared to 19
It is increasing by more than gf / mm ² . Also, Ag 0.31
%, The strength of the alloy (Sample No. 17) added was 86.
Although it is 0 kgf / mm ² , which is lower than that of the alloy containing 0.02% of Ag, the strength is still higher than that of the alloy containing no Ag.

In addition, sample No. shown as a comparison. 9-21
In the case of (alloy containing no Ag or containing excess Ag), the tensile strength is considerably poor.

Example 3 An Al alloy was prepared by adding at least one of Co, Zr, Ti, Ni and Cr to an Al-9Zn-3Mg-1.5Cu-4Mn-Ag alloy. The chemical composition of each alloy is shown in Table 5 and the tensile strength is shown in Table 6. The powder preparation by the Ar atomizing method, the method for preparing the compact, the T6 treatment conditions, etc. are the same as in Example 1.

[0054]

[Table 5]

[0055]

[Table 6]

Example 4 Al-9Zn-3Mg-1.5Cu-4Mn-0.02
0.1 to 0.5% of Si was added to Ag to prepare an Al alloy.

The chemical composition of each alloy powder is shown in Table 7, and the tensile strength is shown in Table 8. The powder preparation by the Ar atomizing method, the method for preparing a compact, the T6 treatment method and the like are the same as in Example 1.

[0058]

[Table 7]

[0059]

[Table 8]

 ─────────────────────────────────────────────────── ─── Continued front page (72) Kohei Kubo, 3-6-8, Kutaro-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Toyo Aluminum Co., Ltd. (72) Takamasa Yokote 3-chome, Kutaro-cho, Chuo-ku, Osaka-shi, Osaka No. 6-8 Toyo Aluminum Co., Ltd. (72) Inventor Kozo Nagamura 1-7 Yamada Ichimachi Tamachi, Sakyo-ku, Kyoto Prefecture Heights Emperor Shugakuin 501

Claims (5)

[Claims] 1. Zn5-11%, Mg2-4.5%, Cu
An Al alloy rapidly solidified powder containing 0.5 to 2% and 0.01 to 0.5% of Ag, and the balance substantially consisting of Al. 2. The Al alloy rapidly solidified powder according to claim 1, further containing 2 to 6% of Mn. 3. The Al alloy rapidly solidified powder according to claim 1, further comprising 0.01 to 2.0% of at least one element selected from Co, Cr, Ni, Zr and Ti. 4. A according to claim 1, further containing Si and / or Ca in a range of up to 1%.
l Alloy rapidly solidified powder. 5. The rapidly solidified Al alloy rapidly solidified powder according to any one of claims 1 to 4 is hot-solidified in air, in a vacuum or in an inert gas atmosphere, and then the resulting compact is aged. A method for manufacturing an aluminum alloy molded material, which is characterized by increasing strength.