ALUMINUM ALLOY POWDER AND METHOD OF PRODUCING THE SAME, ALUMINUM ALLOY EXTRUDED MATERIAL AND METHOD OF PRODUCING THE SAME

- SHOWA DENKO K.K.

An aluminum alloy extruded material consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass %, respectively; and the balance being Al and inevitable impurities, wherein the aluminum alloy extruded material contains an Al—Fe based intermetallic compound, and wherein in a cross-sectional structure of the aluminum alloy extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm. It is possible to provide an aluminum alloy extruded material excellent in mechanical properties at high temperature.

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Description
BACKGROUND OF THE INVENTION Technical Field

The present invention relates to an aluminum alloy powder excellent in mechanical properties at high temperature and a method of producing the same, and an aluminum alloy extruded material (extruded product) excellent in mechanical properties at high temperature and a method of producing the same.

Background Art

A compressor impeller, such as, e.g., a compressor wheel of a turbocharger for use in an automobile internal combustion engine, is rotated at a high speed exceeding 10,000 rpm under high temperature conditions of about 150° C. For this reason, it is required to have high strength and high rigidity under such high temperature. Further, the compressor impeller is required to attain the weight reduction in order to reduce the energy loss, and also required to have strength capable of withstanding a high speed rotation.

For example, conventionally, a compressor impeller has been produced by cutting a cast/forged product of a 2618 alloy (consisting of Cu: 1.9 mass % to 2.7 mass %; Mg: 1.3 mass % to 1.8 mass %; Ni: 0.9 mass % to 1.2 mass %; Fe: 0.9 mass % to 1.3 mass %; Si: 0.1 mass % to 0.25 mass %; Ti: 0.04 mass % to 0.1 mass %; and the balance being Al).

However, due to the recent increase in cutting processing speed, producing a product by cutting an aluminum alloy extruded material has been progressed, which requires further improvement of cutting ability and high temperature strength of the material.

For example, Patent Document 1 discloses a technique of providing an Al—Cu—Mg based aluminum alloy extruded material in which the strength at a high temperature (160° C.) is improved as compared with a conventional one. That is, Document 1 describes a heat resistant aluminum alloy extruded material excellent in high temperature strength and high temperature fatigue properties consisting of: Cu: 3.4% to 5.5% (“%” denotes “mass %”, hereinafter the same); Mg: 1.7% to 2.3%; Ni: 1.0% to 2.5%; Fe: 0.5% to 1.5%; Mn: 0.1% to 0.4%; Zr: 0.05% to 0.3%; Si: less than 0.1%; Ti: less than 0.1%; and the balance being Al and inevitable impurities.

Patent Document 1: Japanese Patent No. 5284935 Problems to be Solved by the Invention

By the way, compressor impellers and the like in the technical field of an internal combustion engine for an as automobile, etc., are required to further rotate at higher speed. Therefore, as an aluminum alloy material as a constituent material of a compressor impeller or the like, a material superior in mechanical properties is desired even in a higher temperature range than in the past. Further, as the properties required for these materials, besides the static strength, it is also required that the dynamic strength, such as creep properties, is excellent.

SUMMARY OF THE INVENTION

The present invention has been made in view of the aforementioned technical background, and aims to provide an aluminum alloy powder excellent in mechanical properties at high temperature and a method of producing the same, and an aluminum alloy extruded material excellent in mechanical properties at high temperature and a method of producing the same.

Means for Solving the Problems

In order to attain the aforementioned object, the present invention provides the following means.

[1] An aluminum alloy powder consisting of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass %, respectively; and the balance being Al and inevitable impurities,

wherein the aluminum alloy powder contains an Al—Fe based intermetallic compound, and

wherein in a cross-sectional structure of the aluminum alloy powder, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm.

[2] The aluminum alloy powder as recited in the aforementioned Item [1],

wherein the aluminum alloy further consists of B: 0.0001 mass % to 0.03 mass %.

[3] A method of producing an aluminum alloy powder, comprising:

quench-solidifying a molten metal of an aluminum alloy by an atomizing method to powder it to thereby obtain an aluminum alloy powder, wherein the aluminum alloy consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities.

[4] An aluminum alloy extruded material consisting of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities,

wherein the aluminum alloy extruded material contains an Al—Fe based intermetallic compound, and

wherein in a cross-sectional structure of the aluminum alloy extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm.

[5] The aluminum alloy extruded material as recited in the aforementioned Item [4],

wherein the aluminum alloy extruded material further contains B: 0.0001 mass % to 0.03 mass %.

[6] The aluminum alloy extruded material as recited in the aforementioned Item [4] or [5],

wherein the intermetallic compound is an Al—Fe—V—Mo based intermetallic compound contains at least Al, Fe, V, and Mo,

wherein in the intermetallic compound, a content rate of Al is 81.60 mass % to 92.37 mass %, a content rate of Fe is 2.58 mass % to 10.05 mass %, a content rate of V is 1.44 mass % to 4.39 mass %, and a content rate of Mo is 2.45 mass % to 3.62 mass %.

[7] A method of producing an aluminum alloy extruded material, comprising:

a compression molding step of compression molding the aluminum alloy powder as recited in the aforementioned Item [1] or [2] to obtain a green compact; and

an extrusion step of hot extruding the green compact to obtain an extruded material,

wherein the extruded material contains in the extruded material an Al—Fe based intermetallic compound, and wherein in a cross-sectional structure of the extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is within a range of 0.1 μm to 3.0 μm.

Effects of the Invention

According to the invention as recited in the aforementioned Item [1], an aluminum alloy powder excellent in mechanical properties at high temperature is provided. Therefore, by using this aluminum alloy powder, it is possible to produce an aluminum alloy extruded material (extruded product) excellent in mechanical properties (static strength, creep properties, etc.) at high temperature.

According to the invention as recited in the aforementioned Item [2], an aluminum alloy powder further improved in mechanical properties (values) at high temperature is provided.

According to the invention as recited in the aforementioned Item [3], the molten metal of the aluminum alloy is quench-solidified by an atomizing method to powder it. Therefore, diffusion of each element of the alloy during the solidification can be suppressed, and coarsening of crystal grains and precipitates can be suppressed. Furthermore, appearance of equilibrium phases and metastable phases can be suppressed. This increases the solid solution amount of Fe which is a transition element. As a result, it is possible to produce an aluminum alloy powder excellent in mechanical properties (static strength, creep properties, etc.) at high temperature. Therefore, by using this aluminum alloy powder, it is possible to produce an aluminum alloy extruded material (extruded product) excellent in mechanical properties at high temperature.

According to the invention as recited in the aforementioned Item [4], an aluminum alloy extruded material (extruded product) excellent in mechanical properties (static strength, creep properties, etc.) at high temperature is provided. This aluminum alloy extruded material is suitable for an internal combustion engine member, such as, e.g., a turbo compressor impeller of a turbocharger for automobiles. In other words, this aluminum alloy extruded material is suitable for, for example, an internal combustion engine member (internal combustion engine parts) configured to rotate at high speed at high temperature.

According to the invention as recited in the aforementioned Item [5], an aluminum alloy extruded material further improved in mechanical properties (value) at high temperature is provided.

According to the invention as recited in the aforementioned Item [6], an aluminum alloy extruded material further improved in mechanical properties (value) at high temperature is provided.

According to the invention as recited in the aforementioned Item [7], an aluminum alloy extruded material (extruded product) excellent in mechanical properties (static strength, creep properties, etc.) at high temperature can be produced. The obtained aluminum alloy extruded material is suitable for an internal combustion engine member, such as, e.g., a turbo compressor impeller of a turbocharger for automobiles. In other words, the obtained aluminum alloy extruded material is suitable for, for example, an internal combustion engine member (internal combustion engine parts) configured to rotate at high speed at high temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of an aluminum alloy extruded material (extruded product) of the present invention.

 EMBODIMENTS FOR CARRYING OUT THE INVENTION

An aluminum alloy powder according to the present invention is configured as follows. That is, the aluminum alloy powder consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass %, respectively; and the balance being Al and inevitable impurities, wherein the aluminum alloy powder contains an Al—Fe based intermetallic compound, and wherein in a cross-sectional structure of the aluminum alloy powder, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm. With such a configuration, an aluminum alloy powder excellent in mechanical properties at high temperature is provided. Therefore, by using the aluminum alloy powder of the present invention, it is possible to produce an aluminum alloy extruded material (extruded product) excellent in mechanical properties (static strength, creep properties, etc.) at high temperature.

The average particle diameter of the aluminum alloy powder is not particularly limited, but it is preferable in the range of 30 μm to 70 μm. When it is 30 μm or more, the yield of the alloy powder production can be markedly improved, and when it is 70 μm or less, contamination of coarse oxides and/or foreign substances can be avoided.

Next, the method of producing an aluminum alloy powder according to the present invention will be described. In the method of producing an aluminum alloy powder, a molten metal of an aluminum alloy is quench-solidified by an atomizing method to powder it to thereby obtain an aluminum alloy powder, wherein the aluminum alloy consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities. With such a production method, it is possible to provide an aluminum alloy powder having the above-described configuration. That is, by the aforementioned production method, an aluminum alloy powder having the aforementioned specific composition in which an Al—Fe based intermetallic compound is contained in the aluminum alloy powder and an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm in a cross-sectional structure of the aluminum alloy powder can be produced.

In the powdering step, the aluminum alloy molten metal having the aforementioned specific composition is prepared by an ordinary dissolution method. The obtained aluminum alloy molten metal is powdered by an atomizing method. The atomizing method is a method in which fine droplets of the aluminum alloy molten metal are misted by a flow of gas, such as, e.g., a nitrogen gas, from a spray nozzle and sprayed to quench-solidify the fine droplets to obtain fine aluminum alloy powder. The cooling rate is preferably from 102° C./s to 105° C./s. It is preferable to obtain an aluminum alloy powder having an average particle diameter of 30 μm to 70 μm. It is preferable to classify the obtained aluminum alloy powder using a sieve.

Note that the aluminum alloy powder (the invention as recited in the aforementioned Item [1]) according to the present invention is not limited to the aluminum alloy powder obtained by the above-mentioned production method, but also includes those obtained by other production methods.

Next, the method of producing an aluminum alloy extruded material according to the present invention will be described. The aluminum powder obtained in the aforementioned powdering step is compression-molded to thereby obtain a green compact (Compression Molding Step). For example, an aluminum alloy powder heated to 250° C. to 300° C. is filled in a die heated to 230° C. to 270° C. and compressed into a predetermined shape to obtain a green compact. Although the pressure of the compression molding is not particularly limited, it is usually preferably set to 0.5 ton/cm2 to 3.0 ton/cm2. Further, it is preferable to prepare a green compact having a relative density of 60% to 90%. Although the shape of the green compact is not particularly limited, it is preferably formed into a cylindrical or disc-shape, considering the subsequent extrusion step.

Next, the green compact obtained in the aforementioned compression molding step is hot-extruded to obtain an extruded material (Extrusion Step). The green compact is subjected to mechanical processing, such as, e.g., facing, as necessary, and then subjected to a degassing treatment, heating, and an extrusion step. The heating temperature of the green compact before extrusion is preferably set to 300° C. to 450° C. In extrusion, for example, the green compact is inserted into an extruding container, pressurized by an extrusion ram, and extruded from an extrusion die into, for example, a round bar shape. At this time, it is preferable that the extrusion container be previously heated to 300° C. to 400° C. By performing the hot-extrusion as mentioned above, plastic deformation of the green compact progresses, and an extruded body in which the aluminum alloy powder (particle) is integrally bonded is obtained. In the extrusion, the extrusion pressure is preferably set to 10 MPa to 25 MPa.

The extruded material 1 obtained in the extrusion step is configured such that an Al—Fe based intermetallic compound is contained in the extruded material and in the cross-sectional structure of the extruded material, the average circle equivalent diameter of the Al—Fe based intermetallic compound is within the range of 0.1 μm to 5.0 μm. Thus, the aluminum alloy extruded material of the present invention can be obtained.

The aluminum alloy extruded material (the aluminum alloy extruded material according to the present invention) obtained by the above-mentioned method of producing an aluminum alloy extruded material according to the present invention is configured such that the aluminum alloy extruded material consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities, wherein the aluminum alloy extruded material contains an Al—Fe based intermetallic compound, and wherein in a cross-sectional structure of the aluminum alloy extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm.

Note that the aluminum alloy extruded material according to the present invention is not limited to the aluminum alloy extruded material obtained by the above-mentioned production method, but also includes those obtained by other production methods.

Next, the composition of the “aluminum alloy” in the aluminum alloy powder according to the present invention, the method of producing the aluminum alloy powder, the aluminum alloy extruded material and the method of producing the aluminum alloy extruded material will be described in detail below. The aluminum alloy consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass %, respectively; and the balance being Al and inevitable impurities.

The Fe (component) is an element that generates an Al—Fe based intermetallic compound having a high melting point and can improve mechanical properties (static strength, creep properties, etc.) in a high temperature range of, for example, 200° C. to 350° C. The Fe content in the aluminum alloy is set so as to fall within the range of 5.0 mass % to 9.0 mass %. When the Fe content rate is less than 5.0 mass %, the strength of the product, such as, e.g., an aluminum alloy extruded material, is decreased. When the Fe content rate exceeds 9.0 mass %, the ductility of the product, such as, e.g., an aluminum alloy extruded material, decreases. Therefore, excellent mechanical properties (static strength, creep properties, etc.) of a product, such as, e.g., an aluminum alloy extrusion material, at high temperature cannot be obtained. Among others, the Fe content rate in the aluminum alloy is preferably within the range of 7.0 mass % to 8.0 mass %.

The V (component) is an element that generates an Al—Fe—V—Mo based intermetallic compound and can improve mechanical properties (static strength, creep properties, etc.) in a high temperature range of, for example, 200° C. to 350° C. The V content in the aluminum alloy is set so as to fall within the range of 0.1 mass % to 3.0 mass %. When the V content rate becomes less than 0.1 mass %, the strength of the product, such as, e.g., an aluminum alloy extruded material, is decreased. When the V content rate exceeds 3.0 mass %, the ductility of the product, such as, e.g., an aluminum alloy extruded material, decreases. Therefore, excellent mechanical properties (static strength, creep properties, etc.) of a products, such as, e.g., an aluminum alloy extrusion material, at high temperature cannot be obtained. Among others, the V content rate in the aluminum alloy is preferably within the range of 1.0 mass % to 2.0 mass %.

The Mo (component) is an element that generates an Al—Fe—V—Mo based intermetallic compound and can improve mechanical properties (static strength, creep properties, etc.) in a high temperature range of, for example, 200° C. to 350° C. The Mo content in the aluminum alloy is set so as to fall within the range of 0.1 mass % to 3.0 mass %. When the Mo content rate becomes less than 0.1 mass %, the strength of the product, such as, e.g., an aluminum alloy extruded material, is decreased. When the Mo content rate exceeds 3.0 mass %, the ductility of the product, such as, e.g., an aluminum alloy extruded material, decreases. Therefore, excellent mechanical properties (static strength, creep properties, etc.) of a product, such as, e.g., an aluminum alloy extrusion material, at high temperature cannot be obtained. Among others, the Mo content rate in the aluminum alloy is preferably within the range of 1.0 mass % to 2.0 mass %.

The aforementioned Zr (component) is an element which does not cause coarsening of an Al—Fe—V—Mo based intermetallic compound and can realize micro crystallization of intermetallic compounds. Further, when Zr is contained, it is possible to improve high temperature strength, and it is also possible to suppress self-diffusion of Al in the Al matrix and to improve creep properties. The Zr content in the aluminum alloy is set so as to fall within the range of 0.1 mass % to 2.0 mass %. When the Zr content rate is less than 0.1 mass %, there arises a problem that the effects of precipitation-strengthening and dispersion-strengthening cannot be exhibited. Further, when the Zr content rate exceeds 2.0 mass %, coarse intermetallic compounds including Zr are generated (see Comparative Example 9 to be described later), so that good mechanical properties cannot be obtained. In particular, the Zr content rate in the aluminum alloy is preferably within the range of 0.5 mass % to 1.5 mass %.

The Ti (component) has a role of forming an Al—(Ti, Zr) based intermetallic compound having an L12 structure with Al in cooperation with Zr. In addition, since the diffusion coefficient of Ti in the Al matrix is small, it is also possible to improve the creep properties. The Ti content rate in the aluminum alloy is set so as to fall within the range of 0.02 mass % to 2.0 mass %. When the Ti content rate is less than 0.02 mass %, there arises a problem that the effects of precipitation-strengthening and dispersion-strengthening cannot be exhibited. Further, when the Ti content rate exceeds 2.0 mass %, the ductility decreases. Therefore, it is impossible to obtain aluminum alloy powder and an aluminum alloy extruded material excellent in mechanical properties (static strength, creep properties, etc.) at high temperature. In particular, the Ti content rate in the aluminum alloy is preferably within the range of 0.5 mass % to 1.0 mass %.

In the present invention, the aluminum alloy further contains one or two kinds of metals selected from the group consisting of Cr and Mn. That is, the aluminum alloy may be a composition further containing Cr: 0.02 mass % to 2.0 mass %, or may be a composition further containing Mn: 0.02 mass % to 2.0 mass %, or may be a composition further containing Cr: 0.02 mass % to 2.0 mass % and Mn: 0.02 mass % to 2.0 mass %. Cr (component) and Mn (component) form a solid solution in the Al mother phase and exert their effects as solid solution strengthening. However, when the extrusion processing temperature reaches 500° C. or higher, precipitation proceeds, which tends to lower the mechanical properties at high temperature. Therefore, it is desirable to set the extrusion processing temperature to less than 500° C. Further, the dispersed particles of Cr and/or Mn have an effect of suppressing grain boundary migration after recrystallization. Therefore, for example, coarsening of the average crystal grain diameter in the ST direction of the parting line structure during the forging step can be suppressed, which makes it possible to obtain fine crystal grains and sub-crystal grains throughout the aluminum alloy extruded material and the forged material of the present invention. As a result, mechanical properties can be further improved.

By containing Zr and Cr and/or Mn at the above-mentioned content rate, they are solid-dissolved in the Al mother phase, which can improve the 0.2% proof stress.

By containing Cr in the amount of 0.02 mass % or more, Cr can be solid-dissolved in the Al mother phase, which can improve mechanical properties (particularly fatigue strength at high temperature). Cr can further enhance abrasion resistance, causing Cr to be solid dissolved in the Al mother phase, which can improve corrosion resistance and increase the temper softening resistance. Therefore, by including Cr, the hardenability can be improved and the heat treatment hardness can be improved. Also, by setting the content rate of Cr to 2.0 mass % or less, it is possible to dissolve Cr in the Al mother phase. Furthermore, coarse intermetallic compounds containing Cr are produced, which can prevent a decrease in the mechanical properties and avoid decrease of thermal conductivity. It is possible to prevent temperature rise of the contact surface due to sliding and to improve scuffing resistance. In particular, when Cr is contained, it is more preferable to set the Cr content rate to 0.05 mass % to 1.5 mass %.

Further, by containing Mn in an amount of 0.02 mass % or more, it is possible to dissolve Mn in the Al mother phase and to improve mechanical properties (in particular, fatigue strength at high temperature) can be obtained. Further, by setting the content rate of Mn to 2.0 mass % or less, it is possible to dissolve Mn in the Al mother phase. Furthermore, coarse intermetallic compounds containing Mn are produced, which can prevent a decrease in the mechanical properties. In particular, when Mn is contained, it is more preferable to set the Mn content rate to 0.05 mass % to 1.5 mass %.

In the present invention, the aluminum alloy may have a configuration (composition) containing 0.0001 mass % to 0.03 mass % of B (boron). By setting the composition containing B at the aforementioned specific ratio, the crystal grain can be refined and the mechanical properties can be improved.

In the present invention, an Al—Fe based intermetallic compound is contained in the aluminum alloy powder or the aluminum alloy extruded material, and an average circle equivalent diameter of the Al—Fe based intermetallic compound is in the range of 0.1 μm to 3.0 μm in a cross-sectional structure of the aluminum alloy powder or the aluminum alloy extruded material. When the average circle equivalent diameter of the intermetallic compound is less than 0.1 μm, the effect of dispersion-strengthening cannot be exhibited. Further, when the average circle equivalent diameter of the intermetallic compound exceeds 3.0 μm, coarse intermetallic compound is formed, which causes a problem that the mechanical properties are deteriorated since fractures occur with the intermetallic compound as a starting point. Particularly, in the cross-sectional structure of the aluminum alloy powder or the aluminum alloy extruded material, the average circle equivalent diameter of the Al—Fe intermetallic compound is preferably within the range of 0.3 μm to 2.0 μm, particularly preferably within the range of 0.4 μm to 1.5 μm.

The Al—Fe based intermetallic compound is not particularly limited, but examples thereof include an Al—Fe—V—Mo based intermetallic compound containing at least Al, Fe, V and Mo, and the like. In the Al—Fe—V—Mo based intermetallic compound, it is preferably configured such that the content rate of Al is 81.60 mass % to 92.37 mass %, the content rate of Fe is 2.58 mass % to 10.05 mass %, the content rate of V is 1.44 mass % to 4.39 mass %, the content rate of Mo is 2.45 mass % to 3.62 mass %. In this case, good mechanical properties can be obtained in the high temperature range of 200° C. or higher.

Note that the circle equivalent diameter of the Al—Fe based intermetallic compound denotes a value converted to a diameter of a circle having the same area as the area of the Al—Fe based intermetallic compound in the SEM photograph (image) of the cross-section of the aluminum alloy powder or the aluminum alloy extruded material.

EXAMPLES

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to those of these examples.

Example 1

An aluminum alloy consisting of: Fe: 8.0 mass %; V: 2.0 mass %; Mo: 2.0 mass %; Zr: 1.0 mass %; Ti: 1.0 mass %; Cr: 0.1 mass %; Al: 85.9 mass %, and inevitable impurities was heated to obtain an aluminum alloy molten metal of 1,000° C. Thereafter, the aluminum alloy molten metal was atomized with gas to be quench-solidified and powdered. Thus, an aluminum alloy powder (aluminum alloy atomized powder) having an average particle diameter of 50 μm was obtained.

Next, the obtained aluminum alloy powder was preheated to a temperature of 280° C. The preheated aluminum alloy powder was filled in a die heated and held at the same temperature of 280° C. and compression-molded at a pressure of 1.5 ton/cm2. Thus, a columnar green compact (formed product) having a diameter of 210 mm and a length of 250 mm was obtained. Next, the obtained green compact was subjected to surfacing by a lathe to a diameter of 203 mm. Thus, a green compact billet was obtained.

Next, the obtained billet was heated to 400° C., and this heated billet was inserted into an extrusion container heated and maintained at 400° C. and having an inner diameter of 210 mm, and extruded at an extrusion ratio of 6.4 by an indirect extrusion method with a die having an inner diameter of 83 mm. Thus, an extruded material 1 was obtained (see FIG. 1).

Example 2

An extruded material 1 was obtained in the same manner as in Example 1 except that an aluminum alloy containing Fe: 8.0 mass %; V: 2.0 mass %; Mo: 2.0 mass %; Zr:

1.0 mass %; Ti: 1.0 mass %; Cr: 0.5 mass %; Al: 85.5 mass %; and inevitable impurities was used as an aluminum for forming an aluminum alloy molten metal.

Examples 3 to 8

An extruded material 1 was obtained in the same manner as in Example 1 except that an aluminum alloy having alloy compositions (containing inevitable impurities) as shown in Table 1 was used as an aluminum for forming an aluminum alloy molten metal.

Examples 9 to 16

An extruded material 1 was obtained in the same manner as in Example 1 except that an aluminum alloy having alloy compositions (containing inevitable impurities) as shown in Table 2 was used as an aluminum for forming an aluminum alloy molten metal.

Examples 17 and 18, Comparative Examples 1 to 6

An extruded material 1 was obtained in the same manner as in Example 1 except that an aluminum alloy having alloy compositions (containing inevitable impurities) as shown in Table 3 was used as an aluminum for forming an aluminum alloy molten metal.

Comparative Examples 7 to 14

An extruded material 1 was obtained in the same manner as in Example 1 except that an aluminum alloy having alloy compositions (containing inevitable impurities) as shown in Table 4 was used as an aluminum for forming an aluminum alloy molten metal.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Alloy Fe (mass %) 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 composition V (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Mo (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Zr (mass %) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Ti (mass %) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Cr (mass %) 0.1 0.5 1.0 — — — 0.5 1.0 Mn (mass %) — — — 0.1 0.5 1.0 0.5 0.3 Si (mass %) — — — — — — — — Cu (mass %) — — — — — — — — Mg (mass %) — — — — — — — — Al (mass %) 85.9  85.5  85.0  85.9  85.5  85.0  85.0  84.7  Average circle equivalent diameter  0.61  0.64  0.67  0.67  0.69  0.73  0.70  0.72 of the intermetallic compound (μm) Evaluation Tensile strength (MPa) at 395/⊚ 395/⊚ 396/⊚ 353/◯ 393/⊚ 395/⊚ 396/⊚ 398/⊚ high temperature (260° C.) Fatigue strength (MPa) at 223/◯ 225/◯ 240/◯ 222/◯ 223/◯ 238/⊚ 232/⊚ 241/⊚ high temperature (260° C.) Creep rupture strength (MPa) 236/⊚ 238/⊚ 241/⊚ 232/⊚ 235/⊚ 239/⊚ 240/⊚ 243/⊚ at high temperature (260° C.) Overall evaluation ◯ ◯ ⊚ ◯ ◯ ⊚ ⊚ ⊚

TABLE 2 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Alloy Fe (mass %) 8.0 8.0 8.0 8.0 8.0 8.0 8.0 8.0 composition V (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 0.5 1.5 Mo (mass %) 2.0 2.0 2.0 2.0 0.5 1.5 2.0 2.0 Zr (mass %) 1.0 1.0 0.5 1.5 1.0 1.0 1.0 1.0 Ti (mass %) 0.1 1.5 1.0 1.0 1.0 1.0 1.0 1.0 Cr (mass %) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Mn (mass %) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Si (mass %) — — — — — — — — Cu (mass %) — — — — — — — — Mg (mass %) — — — — — — — — Al (mass %) 85.9  84.5  85.5  84.5  86.5  85.5  86.5  85.5  Average circle equivalent diameter  0.55  0.79  0.72  0.75  0.66  0.72  0.65  0.75 of the intermetallic compound (μm) Evaluation Tensile strength (MPa) at 375/⊚ 460/⊚ 400/⊚ 433/⊚ 373/⊚ 419/⊚ 371/⊚ 424/⊚ high temperature (260° C.) Fatigue strength (MPa) at 225/◯ 245/⊚ 232/⊚ 245/⊚ 224/◯ 235/⊚ 226/⊚ 244/⊚ high temperature (260° C.) Creep rupture strength (MPa) 218/⊚ 260/⊚ 236/⊚ 255/⊚ 219/⊚ 229/⊚ 215/◯ 230/⊚ at high temperature (260° C.) Overall evaluation ◯ ⊚ ⊚ ⊚ ◯ ⊚ ◯ ⊚

TABLE 3 Comp. Comp. Comp. Comp. Comp. Comp. Ex. 17 Ex. 18 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Alloy Fe (mass %) 6.0 7.0 8.0 8.0 8.0 8.0 8.0 8.0 composition V (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 2.0 — Mo (mass %) 2.0 2.0 — 2.0 2.0 2.0 — 2.0 Zr (mass %) 1.0 1.0 1.0 1.0 1.0 — 1.0 1.0 Ti (mass %) 1.0 1.0 — 1.0 — 1.0 1.0 1.0 Cr (mass %) 0.5 0.5 — — 0.5 0.5 0.5 0.5 Mn (mass %) 0.5 0.5 — — 0.5 0.5 0.5 0.5 Si (mass %) — — 2.0 — — — — — Cu (mass %) — —  0.13 — — — — — Mg (mass %) — —  0.13 — — — — — Al (mass %) 87.0  86.0  86.74 86.0  86.0  86.0  87.0  87.0  Average circle equivalent diameter  0.58  0.62  0.95  0.63  0.59  0.60  0.62  0.57 of the intermetallic compound (μm) Evaluation Tensile strength (MPa) at 362/⊚ 390/⊚ 272/X 398/⊚ 348/Δ 365/⊚ 352/◯ 355/◯ high temperature (260° C.) Fatigue strength (MPa) at 222/◯ 226/⊚ 165/X 220/Δ 205/X 195/X 192/X 193/X high temperature (260° C.) Creep rupture strength (MPa) 211/◯ 238/⊚ 172/X 235/⊚ 214/◯ 199/X 197/X 195/X at high temperature (260° C.) Overall evaluation ◯ ⊚ X Δ X X X X

TABLE 4 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Comp. Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Alloy Fe (mass %) 3.0 8.0 8.0 8.0 8.0 8.0 8.0 10.0  composition V (mass %) 2.0 2.0 2.0 2.0 2.0 2.0 4.0 1.0 Mo (mass %) 2.0 2.0 2.0 2.0 2.0 4.0 1.0 2.0 Zr (mass %) 1.0 1.0 1.0 1.0 2.5 1.0 1.0 1.0 Ti (mass %) 1.0 1.0 1.0 3.5 1.0 1.0 1.0 1.0 Cr (mass %) 0.5 0.5 4.0 0.5 0.5 0.5 0.5 0.5 Mn (mass %) 0.5 4.0 0.5 0.5 0.5 0.5 0.5 0.5 Si (mass %) — — — — — — — — Cu (mass %) — — — — — — — — Mg (mass %) — — — — — — — — Al (mass %) 90.0  81.5  81.5  82.5  83.5  83.0  84.0  84.0  Average circle equivalent diameter  0.55  3.29  3.45  3.41  3.24  3.30  3.32  4.62 of the intermetallic compound (μm) Evaluation Tensile strength (MPa) at 279/X 309/X 320/X 311/X 328/X 315/X 311/X 300/X high temperature (260° C.) Fatigue strength (MPa) at 165/X 185/X 186/X 180/X 183/X 182/X 189/X 175/X high temperature (260° C.) Creep rupture strength (MPa) 118/X 194/X 199/X 191/X 192/X 194/X 193/X 185/X at high temperature (260° C.) Overall evaluation X X X X X X X X

Each aluminum alloy extruded material (extruded product) obtained as described above was evaluated based on the following evaluation method. The results are shown in Tables 1 and 4. Note that in each element column of Tables 1 to 4, the symbol “−” indicates that it was a numerical value lower than the detection limit (0.005 mass %) (i.e., no element was detected).

Further note that the “average circle equivalent diameter (μm) of intermetallic compound” in Tables 1 to 4 means that the average circle equivalent diameter (μm) of an Al—Fe—V—Mo based intermetallic compound (intermetallic compound containing at least Al, Fe, V, and Mo) existing in the matrix of each aluminum alloy extrusion material. This “average circle equivalent diameter (μm) of intermetallic compound” was obtained as follows. From the central portion (intermediate bisecting position) of the obtained aluminum alloy extruded material (columnar article) in the L direction (longitudinal direction, i.e., axial direction), samples for tissue observation having a size of 10 mm in length×10 mm in width×10 mm in thickness were cut into pieces. This sample piece was micro-polished using a cross-section sample preparation apparatus (cross section polisher). Then, an SEM photograph (scanning electron microscope photograph) of this sample piece after the micro polishing was taken. An average circle equivalent diameter (μm) of the intermetallic compound was obtained (evaluated) was obtained from the photograph image. An average circle equivalent diameter for ten Al—Fe—V—Mo based intermetallic compounds existing in the field of view 1.5815 mm2 in the SEM photograph was obtained.

<Tensile Strength Evaluation Method at High Temperature>

The obtained aluminum alloy extruded material (cylindrical article) was processed into a tensile test piece having a gauge distance of 20 mm and a parallel portion diameter of 4 mm. Then, the high temperature tensile strength (tensile strength at 260° C.) was measured by performing a high temperature tensile test of the tensile test piece. The high temperature tensile test was performed under the measurement environment of 260° C. after holding the high temperature tensile test piece at 260° C. for 100 hours. The evaluation was made based on the following criteria.

(Judgment Criteria)

“⊚”: Tensile strength at 260° C. is 356 MPa or more
“◯”: Tensile strength at 260° C. is 351 MPa or more and 355 MPa or less
“Δ”: Tensile strength at 260° C. is 346 MPa or more and 350 MPa or less
“x”: Tensile strength at 260° C. is 345 MPa or less

<Fatigue Test Method at High Temperature>

The obtained aluminum alloy extruded material (cylindrical article) was processed into a fatigue test piece having a gauge distance of 30 mm and a parallel portion diameter of 8 mm. Then, the high temperature fatigue strength (fatigue strength at 260° C.) was measured by performing a high temperature fatigue test of the fatigue test piece. The high temperature fatigue test was performed by holding the fatigue test piece at 260° C. for 100 hours and then testing 500,000 times under the measurement environment of 260° C. at a repetition rate of 3,600 rpm. The evaluation was made based on the following criteria.

(Judgment Criteria)

“⊚”: Fatigue strength at 260° C. is 226 MPa or more
“◯”: Fatigue strength at 260° C. is 221 MPa or more and 225 MPa or less
“Δ”: Fatigue strength at 260° C. is 216 MPa or more and 220 MPa or less
“x”: Fatigue strength at 260° C. is 215 MPa or less

<Creep Test Method at High Temperature>

The obtained aluminum alloy extruded material (cylindrical article) was processed into a creep test piece having a gauge distance of 30 mm and a parallel portion diameter of 6 mm. Then, the high temperature creep properties (creep properties at 260° C.) were measured by performing a high temperature creep test of the creep test piece. The high temperature creep test was performed under the measurement environment of 260° C. after holding the creep test piece at 260° C. for 100 hours. The creep rupture strength under the condition of temperature: 260° C. and rupture time: 300 hours was calculated and evaluated based on the following criteria.

(Judgment Criteria)

“⊚”: Creep rupture strength at 260° C. is 216 MPa or more
“◯”: Creep rupture strength at 260° C. is 211 MPa or more and 215 MPa or less
“Δ”: Creep rupture strength at 260° C. is 206 MPa or more and 210 MPa or less
“x”: Creep rupture strength at 260° C. is 205 MPa or less

As is apparent from the tables, the aluminum alloy extruded materials of Examples 1 to 18 according to the present invention were excellent in various mechanical properties at high temperature (260° C.).

On the other hand, the aluminum alloy extruded materials of Comparative Examples 1 to 14 falling outside the specified range of the present invention were inferior to the mechanical properties at high temperature (260° C.).

INDUSTRIAL APPLICABILITY

The aluminum alloy powder, and the aluminum alloy material formed using the aluminum alloy powder obtained by the production method of the present invention are excellent in mechanical properties at high temperature. Further, since the aluminum alloy extruded material according to the present invention and the aluminum alloy extruded material obtained by the production method of the present invention are excellent in mechanical properties at high temperature, it is suitably used as an internal combustion engine member (internal combustion engine parts) which rotates at high speed under high temperature, such as, e.g., a turbocharger turbo compressor impeller used for an internal combustion engine of an automobile.

The present application claims priority to Japanese Patent Application No. 2018-71463 filed on Apr. 3, 2018, the entire disclosure of which is incorporated herein by reference in its entirety.

It should be understood that the terms and expressions used herein are used for explanation and have no intention to be used to construe in a limited manner, do not eliminate any equivalents of features shown and mentioned herein, and allow various modifications falling within the claimed scope of the present invention. The present invention allows any design changes unless departing from its spirit within the scope of the claims.

DESCRIPTION OF REFERENCE SYMBOLS

  • 1: aluminum alloy extruded material (extruded product)

Claims

1. An aluminum alloy powder consisting of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass %, respectively; and the balance being Al and inevitable impurities,

wherein the aluminum alloy powder contains an Al—Fe based intermetallic compound, and
wherein in a cross-sectional structure of the aluminum alloy powder, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm.

2. The aluminum alloy powder as recited in claim 1,

wherein the aluminum alloy further consists of B: 0.0001 mass % to 0.03 mass %.

3. A method of producing an aluminum alloy powder, comprising:

quench-solidifying a molten metal of an aluminum alloy by an atomizing method to powder it to thereby obtain an aluminum alloy powder, wherein the aluminum alloy consists of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities.

4. An aluminum alloy extruded material consisting of: Fe: 5.0 mass % to 9.0 mass %; V: 0.1 mass % to 3.0 mass %; Mo: 0.1 mass % to 3.0 mass %; Zr: 0.1 mass % to 2.0 mass %; Ti: 0.02 mass % to 2.0 mass %; one or two kinds of metals selected from the group consisting of Cr and Mn: 0.02 mass % to 2.0 mass % of, respectively; and the balance being Al and inevitable impurities,

wherein the aluminum alloy extruded material contains an Al—Fe based intermetallic compound, and
wherein in a cross-sectional structure of the aluminum alloy extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is in a range of 0.1 μm to 3.0 μm.

5. The aluminum alloy extruded material as recited in claim 4,

wherein the aluminum alloy extruded material further contains B: 0.0001 mass % to 0.03 mass %.

6. The aluminum alloy extruded material as recited in claim 4,

wherein the intermetallic compound is an Al—Fe—V—Mo based intermetallic compound contains at least Al, Fe, V, and Mo,
wherein in the intermetallic compound, a content rate of Al is 81.60 mass % to 92.37 mass %, a content rate of Fe is 2.58 mass % to 10.05 mass %, a content rate of V is 1.44 mass % to 4.39 mass %, and a content rate of Mo is 2.45 mass % to 3.62 mass %.

7. A method of producing an aluminum alloy extruded material, comprising:

a compression molding step of compression molding the aluminum alloy powder as recited in claim 1 to obtain a green compact; and
an extrusion step of hot extruding the green compact to obtain an extruded material,
wherein the extruded material contains in the extruded material an Al—Fe based intermetallic compound, and wherein in a cross-sectional structure of the extruded material, an average circle equivalent diameter of the Al—Fe based intermetallic compound is within a range of 0.1 μm to 3.0 μm.
Patent History
Publication number: 20190299296
Type: Application
Filed: Apr 3, 2019
Publication Date: Oct 3, 2019
Applicant: SHOWA DENKO K.K. (Tokyo)
Inventor: Takuya ARAYAMA (Fukushima)
Application Number: 16/374,044
Classifications
International Classification: B22F 3/20 (20060101); B22F 9/08 (20060101); C22C 21/00 (20060101);