JPH10265918A - Aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum alloy having a specific Charpy impact value, excellent in formability and workability, and suitable for use in production on an industrial scale by incorporating Fe, Cr, and Ni and specifying a composition and a structure, respectively. SOLUTION: This alloy is an Al alloy which contains, by weight, 2-7% Fe, 2-12$ Cr, and 1-10% Ni (where 7<=Fe+Cr+Ni<=15 is satisfied) and in which at least a part of alloy structure is composed of quasi-crystal and Charpy impact value is regulated to >=2 J/cm<2> . Further, 0.01-2.5% of Zr can be incorporated into this alloy (where 7<=Fe+Cr+Ni+Zr<=15 is satisfied). Fe is an essential component for constituting a quasi-crystal formed mainly in the alloy, and Fe atoms which do not constitute quasi-crystals form Al3 Fe, etc., and these contribute to the improvement of heat resistance, etc.; however, incorporation of Fe in an amount exceeding 7% causes deterioration in toughness and ductility. Although Cr makes the same contribution as Fe does, its incorporation in an amount exceeding 12% causes deterioration in ductility. Ni contributes to the improvement, e.g. of the strengthening and stabilization of quasi-crystals, but the possibility of causing deterioration in toughness and ductility is brought about when Ni content exceeds 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an aluminum alloy.

[0002]

2. Description of the Related Art Aluminum alloys are lightweight, thermally conductive,
Excellent properties such as specific strength, aircraft, automobiles,
Widely used for motorcycles and other mechanical parts. In particular, in recent years, many aluminum alloys or composite materials thereof having high strength and excellent heat resistance have been developed.

[0003] However, these materials have extremely poor hot workability as well as cold workability, and cannot be formed by an existing extruder, forging machine or the like in many cases. Further, even if it can be formed, it is difficult to avoid defects such as cracks and chatter. Even if the molding is sound and there are no such defects, the toughness of the molded article at room temperature itself is insufficient. For this reason, it is extremely difficult to further perform cold working on the obtained molded product.

In this regard, as a high-strength and heat-resistant aluminum alloy, a composite material in which whiskers and ceramic particles are dispersed in aluminum powder, an amorphous alloy by a mechanical alloying method, a super-quenching method, etc. Although intermetallic compounds have been developed, alloys based on these technologies are not suitable for industrial-scale production due to the above-mentioned problems, complicated production processes, and high production costs. hard.

Specifically, in a composite material using the above-mentioned whiskers or the like as a dispersion strengthening material, the whiskers or the like as the dispersing material are expensive, and the process of dispersing the whiskers requires time and effort, and the evaluation is easy. Not. Further, the more the material is reinforced, the poorer the ductility and the lower the formability.

[0006] In the mechanical alloying method, a small amount of powder must be treated in a ball mill for a long time, so that productivity is extremely low. In addition, oxygen and the like are picked up during the treatment, so that toughness and ductility gradually decrease. Go. In addition, the obtained powder has a large number of dislocations and is work-hardened, which causes a hindrance to moldability.

[0007] In the case of an amorphous alloy powder obtained by the ultra-quenching method, a device for quenching and a high-pressure gas used for the device are expensive. Further, expensive rare metals such as yttrium and cerium are also required as amorphous forming elements. Further, the obtained alloy powder is not easily deformed at a crystallization temperature or lower, and thus cannot be easily formed.

On the other hand, there is a method disclosed in Japanese Patent Application Laid-Open No. 3-267355 as a technique utilizing amorphous. However, since a Cr content of 17.6% by weight or more is required, a decrease in ductility can be avoided. Absent. In addition, there are still many points to be improved, such as an increase in weight due to Cr, complicated processing such as amorphization, and a problem of formability at a crystallization temperature or lower.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an aluminum alloy which is particularly excellent in formability and workability and is suitable for production on an industrial scale.

[0010]

Means for Solving the Problems The present inventor has conducted intensive studies in view of these problems of the prior art, and as a result, has found that an aluminum alloy having a specific composition and structure can achieve the above object, and completed the present invention. I came to.

That is, the present invention relates to an alloy based on aluminum, comprising: (1) Fe: 2 to 7% by weight;
r: 2 to 12% by weight and Ni: 1 to 10% by weight (provided that
7% by weight ≦ Fe + Cr + Ni ≦ 15% by weight)
(2) At least a part of the alloy structure is a quasicrystal,
(3) An aluminum alloy having a Charpy impact value of ² J / cm ² or more.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described together with its embodiments.

First, each component in the aluminum alloy of the present invention will be described. However, since each component of the aluminum alloy of the present invention interacts with each other, it is not always appropriate to individually discuss the reasons for limiting each component, and a general reason will be described.

Fe is a quasicrystal (Al—Cr—Fe (eg, Al) formed mainly in the aluminum alloy of the present invention.
₈₀ Cr _13.5 Fe _6.5 ) -based quasicrystal or the like), and is usually about 2 to 7% by weight, preferably 2.5 to 5% by weight. Fe atoms that do not form a quasicrystal form Al ₃ Fe, Al ₉ FeNi, and the like, which contribute to improvement in heat resistance and the like. However, if the content exceeds 7% by weight, Al ₃ Fe, Al ₉ FeNi, and the like are likely to be coarsened, which may cause a decrease in toughness and ductility.

Cr is a component necessary for constituting the quasicrystalline phase in the aluminum alloy of the present invention, mainly like Fe, and is usually about 2 to 12% by weight, preferably 3 to 12% by weight.
It may be set to 6% by weight. If the content is more than 12% by weight, ductility may be reduced and elongation at break may be almost eliminated. Cr atoms that do not constitute a quasicrystal are Al ₁₃ Cr
As a result of forming ₂ etc., it contributes to improvement of heat resistance and the like.

Ni is mainly composed of the above Al ₈₀ Cr _13.5 Fe
_It is a substitutional solid solution in _6.5 -type quasicrystals and contributes to strengthening of quasicrystals and improvement of stability. The content is usually 1-1.
The content may be about 0% by weight, preferably 2 to 6% by weight.
Ni atoms that do not constitute a quasicrystal are, for example, Al ₃ Ni, A
A compound such as l ₉ FeNi or a eutectic structure with Al is formed. If the Ni content exceeds 10% by weight, the above compounds and the like tend to be coarsened, and the toughness and ductility may be reduced.

In the aluminum alloy of the present invention, Zr
Is also included. Zr forms a solid solution in the Al matrix within a certain range, and can contribute to solid solution strengthening. Further, since Zr in Al has a low diffusion coefficient, the solid solution state is relatively stable even at a high temperature. From such a viewpoint, the Zr content may be generally about 0.01 to 2.5% by weight, preferably 0.1 to 1% by weight. Also,
As described above, even if the amount is small compared to the other components, Zr is also effective for refining the structure. When the Zr content exceeds 2.5% by weight, compounds such as Al ₃ Zr are crystallized, and the toughness and ductility may be reduced. In addition, in this case, the melting point of the alloy may increase, and the viscosity of the molten metal may increase.

Furthermore, in the aluminum alloy of the present invention, in addition to the above elements, Mg, Si, Cu, Mn, V, Ti,
At least one of Mo and the like in an amount of 0.01 to 3% by weight, respectively
Can also be added within the range.

If the added amount exceeds 3% by weight, different problems may occur depending on the respective elements as follows. In the case of V, Ti, Mo, and Mn, a coarse compound is formed, and ductility may be significantly reduced. Further, particularly in the case of Si, crystallization or precipitation may occur by itself, and the fracture toughness may be reduced. Further, in the case of Mg and Cu, Cu is an element that contributes to strength from room temperature to around 200 ° C. and has a function of improving hot workability, while Cu easily forms a compound with Fe, Al, and the like. Mg has a high probability of forming an oxide. The total addition amount of these elements such as Mg is preferably 5% by weight or less, particularly preferably 0.01 to 3% by weight from the viewpoint of formability and toughness.

In the present invention, components other than the above components may be contained within a range that does not impair the effects of the present invention.

In the aluminum alloy of the present invention, at least a part of its structure is composed of a quasicrystal. The quasi-crystal has an intermediate structure between amorphous (amorphous) and normal crystal, and includes, for example, Al-Cr alloy, Al-Mn alloy, Al-Cu-X (X is Fe, Mn, Li, etc.). ) Also confirmed in alloys and the like. Its crystal structure is characterized by an atomic arrangement with a 5-fold axis like an icosahedron,
Electron diffraction shows a diffraction image symmetrical five or ten times.
Further, in X-ray diffraction, it exhibits a unique peak. The aluminum alloy of the present invention contains the same or similar quasicrystal as the Al-Cr-Fe quasicrystal. And this quasicrystal contributes to improvement of high-temperature strength etc., especially, without drastic reduction of toughness.

The quasicrystal size in the aluminum alloy of the present invention is usually 0.2 μm or less, more preferably 0.05 to 0.1 μm. Quasicrystal size 0.2μ
If it exceeds m, desired characteristics (workability, moldability, etc.) cannot be obtained.

The volume fraction is usually about 0.1 to 20% by volume, preferably 1 to 10% by volume. If the volume fraction is less than 0.1% by volume, desired strength, heat resistance and the like cannot be obtained. If it exceeds 20% by volume, the slip surface of the matrix is relatively reduced, and the workability and
Moldability and the like are reduced. The volume fraction can be determined, for example, from a micrograph.

The aluminum alloy of the present invention has a Charpy impact value of ² J / cm ² or more, preferably 2.3 J / cm ^2.
m ² or more. The higher the Charpy impact value, the higher the ductility,
It can be said that it has excellent moldability and the like. The method for measuring the Charpy impact value in the present invention will be described in Examples described later.

For the method of producing the aluminum alloy of the present invention, rapid solidification is suitable, for example, from the viewpoint of forming a desired amount of quasicrystal, and examples thereof include atomizing, quenching roll, rotating disk, and spray drum methods. And the atomization method is particularly preferable.

The cooling rate is usually 10 ² to 10 ⁶ ° C / sec.
Degree, preferably 10 ³ to 10 ⁵ ° C / sec. When the cooling rate is less than 10 ² ° C / sec, not only a desired quasicrystal cannot be obtained, but also a coarse intermetallic compound is crystallized, and there is a possibility that toughness and ductility and formability are significantly reduced. On the other hand, when it exceeds 10 ⁶ ° C / sec, the abundance ratio of quasicrystals becomes too large, and the movement of dislocations in the matrix is hindered.

It is desirable that the powder having a particle size distribution of usually about 5 to 45 μm is adjusted to 80% by weight or more of the whole powder. If the amount of powder exceeding 45 μm is too large, it becomes difficult to obtain a desired cooling rate. On the other hand, if the amount of the powder having a particle size of less than 5 μm is too large, the oxide (oxygen amount) is increased, leading to a decrease in toughness and ductility, a molding failure and the like.

The spray medium and the spray atmosphere may be appropriately determined according to the use of the final product and the like, and may be, for example, any of the air, an inert gas, or a mixed gas thereof. For example, when limiting the amount of oxygen, an inert gas may be introduced as needed.

The obtained powder is classified if necessary. The classification may be performed according to a known powder classification method using a sieve or the like. The coarse powder particles are likely to include, for example, those in which quasicrystals are not formed, those in which coarse crystals are formed, and the like. It is preferable to remove these powder particles in advance by classification. The particle size of the powder is usually 150 μm or less, preferably 45 μm or less, as the aluminum alloy of the present invention. The shape of the powder is not particularly limited, and may be any shape such as a true sphere, a spheroid, an irregular shape, a teardrop, and a flat shape.

When the aluminum alloy powder of the present invention is further solidified and compacted, any of the industrially known molding methods can be employed. For example, if necessary
Preforming with P or cold press, then hot extrusion, hot powder forging, hot pressing, HIP, etc.
Sintering may be performed. Among these, the method by hot powder forging is preferable from an industrial production point of view.

Usually, an extruded material obtained by hot extrusion or the like tends to have anisotropy between the extrusion direction and a direction perpendicular to the extrusion direction.
A difference of about 20% may occur. On the other hand, in the case of hot powder forging, even if such anisotropy exists, the difference is usually 5% or less. The yield of the extruded material is usually around 70%, whereas the yield ratio is usually 9% in the case of hot powder forging because of the near net shape.
8% or more. In addition, many extruded billets are large and often require a long time for heating. On the other hand, in the case of hot powder forging, since it is a near-net shape, the required minimum size is sufficient, and the time required for heating can be reduced.

Since the aluminum alloy of the present invention has good ductility over a wide temperature range, it can be manufactured by hot powder forging even for a component having a complicated shape, and prevents formation of a coarse compound from a quasicrystal. In this sense, a hot powder forging method having a short heating time is preferable. On the other hand, in the case of a product having a simple shape (for example, a bar shape, a pipe shape, or the like), extrusion may be more advantageous in terms of equipment such as a device and a mold. Therefore, in the aluminum alloy of the present invention,
What is necessary is just to select a molding method suitably according to the shape of a final product, etc.

The aluminum alloy of the present invention can be hot-formed in the atmosphere. However, if the amount of oxygen is a problem depending on the application, a degassing step, a treatment in an inert gas, etc., may be performed as necessary. You may go. Further, the aluminum alloy of the present invention,
Since it also has a deformability at room temperature, it is possible to easily perform correction such as distortion or caulking by cold forging or pressing, or complicated processing such as machining.

[0034]

In the aluminum alloy of the present invention, the quasicrystalline phase and the crystalline intermetallic compound in the alloy structure mainly contribute to the improvement of heat resistance. In particular, the quasicrystalline phase is finely and uniformly dispersed in the structure, and is stable even at the processing or molding temperature, so that the characteristics do not deteriorate due to coarsening or phase transformation. In addition, there is relatively little deformation resistance in the matrix, excellent hot formability, and good cold workability thereafter. Furthermore, it has excellent toughness at room temperature.

More specifically, the aluminum alloy of the present invention has excellent strength and ductility in a wide temperature range from room temperature to a high temperature of about 300 ° C. Also excellent in moldability,
Since the quasicrystalline phase generated in the alloy is also stable, there is an advantage that processing and heat treatment can be performed while maintaining its various characteristics. Further, since it is excellent in toughness at room temperature, various processes are possible, and the reliability as a material for various uses is high.

The aluminum alloy of the present invention having such features can be widely used for structural materials, mechanical materials, transportation machinery members and the like.

[0037]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Example 1 An alloy melt having the composition shown in Table 1 was prepared and pulverized by an atomizing method. The obtained powder was classified into −45 μm and cold preformed into a billet having a diameter of 30 mm and a height of about 80 mm. Thereafter, the mixture was heated at 350 ° C. for 30 minutes and extruded at the same temperature at an extrusion ratio of 10.

A tensile test piece was prepared from the obtained extruded rod, and kept at room temperature, 200 ° C. and 300 ° C. for 100 hours, and then a tensile test was conducted at the same temperature. The results are shown in Tables 1 to 3. In addition, a Charpy test was performed at room temperature. The Charpy test was performed according to JIS Z2242. The cross section of the Charpy test specimen was about 7
JIS3 from rectangular extruded material of mm × 11mm
A test piece with a U-notch in a half width size of the test piece was cut out and used. Table 1 shows the results.

The critical upsetting ratio was measured as an index of hot forming / workability. Generally, the larger the value, the better the deformability. Table 1 also shows the results. In addition, the method of measuring the critical upsetting rate is as follows:
m, 10 test pieces were prepared, each test piece was sandwiched between cylindrical molds, and the upsetting rate was changed by changing the upsetting rate at 450 ° C. at a forging speed of 70 mm / sec.
(%) Was determined according to the following equation.

EhC = (h0−hc) × 100 / h0 (where h0 is the height (15 mm) of the sample before deformation, h
c: height of sample after deformation)

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

Example 2 The raw material powder obtained in Example 1 was used in a cold press to obtain φ5.
Hot forging of a preform of 9 × 50 mm (H) in a φ61 mold (forging temperature: 350 ° C., holding time: 15
Min). Each test piece was prepared from the obtained forged body,
The same test as in Example 1 was performed. Table 4-
6 is shown.

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

From the above results, it can be seen that the aluminum alloy of the present invention has good formability, exhibits excellent strength and ductility in the temperature range from room temperature to 300 ° C., and also has excellent impact resistance at room temperature. .

[Brief description of the drawings]

FIG. 1 is a view showing a result of an X-ray diffraction analysis of a sintered body of Example 1.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Kusui 3-6-8 Kutaro-cho, Chuo-ku, Osaka City, Osaka Prefecture Inside Toyo Aluminum Co., Ltd. (72) Kohei Kubo 3-chome Kutaro-cho, Chuo-ku, Osaka City, Osaka No. 6-8 Inside Toyo Aluminum Co., Ltd. (72) Inventor Kenji Matsuki 3190 Gofuku, Toyama City, Toyama Prefecture

Claims (4)

[Claims] An alloy based on aluminum, comprising: (1) 2 to 7% by weight of Fe, 2 to 12% by weight of Cr
And Ni: 1 to 10% by weight (however, 7% by weight ≦ Fe + C
(2) At least a part of the alloy structure is a quasicrystal, and (3) a Charpy impact value is ² J / cm ² or more. 2. An alloy based on aluminum, comprising: (1) 2 to 7% by weight of Fe, 2 to 12% by weight of Cr, 1 to 10% by weight of Ni, and 0.01 to 2% of Zr. 5
Wt% (however, 7 wt% ≦ Fe + Cr + Ni + Zr ≦ 1
(2) at least a part of the alloy structure is a quasicrystal, and (3) the Charpy impact value is 2 J / cm.
Aluminum alloy characterized by being ² or more. 3. The aluminum alloy according to claim 1, wherein the size of the quasicrystal is 0.2 μm or less. 4. The aluminum alloy according to claim 1, wherein the volume fraction of the quasicrystal is 0.1 to 20% by volume.