JP2000328164A - Heat-resistant aluminum alloy excellent in strength and toughness and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant aluminum alloy excellent in strength and toughness capable of maintaining high strength even at a high temperature, and a method for producing the same. SOLUTION: An Al-Si-Fe-based aluminum alloy A containing at least Si: 15% or more and less than 30% (weight%, the same applies hereinafter) and Fe: 1.0% or more and less than 5.0%.
And an Al—Fe-based aluminum alloy B containing at least 5.0% or more and less than 10.0% of Fe, and the mixing weight ratio, B / (A + B), is 0.1 or more and 0.1% or less.
By setting it to less than 4, the Al-Fe-based aluminum alloy B
Forms an Al-Fe intermetallic compound, and a spherical Al-Fe intermetallic compound is mixed in the aluminum alloy A,
As a result, high strength is maintained even at high temperatures, and excellent toughness is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant aluminum alloy having excellent strength and toughness applicable to connecting rods, pistons, brake discs and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Al- produced using rapid solidification technology.
Since high Si aluminum alloys are expected to have excellent properties such as high Young's modulus, low coefficient of linear expansion, high strength, and abrasion resistance, various alloys have been developed especially suitable for vehicle components. Have been. For example, an Al-high Si-Cu-Mg-based aluminum alloy having high strength and wear resistance (Japanese Patent No. 1689710) has been proposed by the present applicant. Aluminum alloy with improved properties (Patent No. 173480)
No. 8) has also been proposed by the present applicant.

That is, when Fe is added to an Al—high Si aluminum alloy, Al ₈ SiFe ₂ ,
_{Al 5 SiFe, Al-Si-} F , such as Al ₄ Si ₂ Fe
It constitutes an e-based intermetallic compound, and the fineness of these intermetallic compounds enhances the strength and is applicable to certain applications. However, the Al-Si-Fe-based intermetallic compound does not necessarily contribute much to the improvement of high-temperature strength, and the strength becomes insufficient at around 200 ° C., and further, ductility and toughness are not affected by temperature conditions. There is a disadvantage that it decreases.

Therefore, the aluminum alloy proposed by the present applicant is difficult to apply to various vehicle parts requiring high-temperature strength, for example, connecting rods, pistons, brake discs and the like. For example, the thickness must be increased, and the purpose of miniaturization and weight reduction cannot be achieved.

In order to obtain high strength even at a high temperature in an aluminum alloy obtained by adding Fe to an Al-high Si-based aluminum alloy, it is difficult to increase the particle size of the particles even at a high temperature and to obtain a high strength Al ₃ Fe. , Al ₆ Fe and other Al-Fe intermetallic compounds, and these intermetallic compounds must be finely dispersed. However, when solidifying a molten metal in a state where Fe is added to an Al-high Si-based aluminum alloy, an Al-Fe-Si-based intermetallic compound is formed unless Fe is added in excess of a stoichiometric ratio,
It does not constitute an Al-Fe intermetallic compound.

[0006]

SUMMARY OF THE INVENTION The present invention provides an Al-high S
The purpose of the present invention is to solve the above-mentioned conventional problems in an aluminum alloy in which Fe is added to an i-based aluminum alloy, and its purpose is to maintain high strength even at a high temperature. An object of the present invention is to provide a heat-resistant aluminum alloy having excellent strength and toughness applicable to connecting rods, pistons, brake disks, and the like that require heat resistance, and a method for producing the same.

[0007]

Means for Solving the Problems The present inventors have attempted to obtain an aluminum alloy which can achieve the above object by using Al-
As a result of intensive studies on the relationship between the composition, matrix properties, and high-temperature strength of the high-Si-Fe-based alloy, Si 15%
Al-Si-Fe-based aluminum alloy A powder containing at least 30% and less than 1.0% Fe and less than 5.0%,
Al-Fe containing at least 5.0% Fe and less than 10.0%
Weight ratio of B-based aluminum alloy B, B / (A +
B) is mixed so as to be 0.1 or more and less than 0.4, and solidified by powder metallurgy to form an Al-Fe intermetallic compound, and this compound is finely dispersed, Has also been found to be excellent in strength and toughness. In addition, it has been found that similar results can be obtained by spray forming instead of powder metallurgy, and the present invention has been completed.

That is, according to the present invention, at least S
i—Al—Si—Fe-based aluminum alloy A containing 15% or more and less than 30% and Fe 1.0% or more and less than 5.0%
And an Al-Fe-based aluminum alloy B containing at least 5.0% or more and less than 10.0% of Fe, and the mixed weight ratio B / (A + B) is 0.1 or more and 0.4 or more.
And a heat-resistant aluminum alloy excellent in strength and toughness, characterized by being less than.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The Al-Si-Fe-based aluminum alloy A (hereinafter simply referred to as aluminum alloy A) is obtained by rapidly solidifying a molten metal by a gas atomizing method or the like. In the range of
It is important that e is contained in a range of 1.0% or more and less than 5.0%, and when Si is in this range, hard Si particles are sufficiently dispersed in the aluminum alloy A and required abrasion resistance is required. Properties are obtained, the modulus of elasticity is improved, and the coefficient of linear expansion is reduced.
If the Si content is less than 15%, the wear resistance becomes insufficient, and
When the content is above, the toughness is reduced, and the machinability, the extrudability, the forgeability, etc. are reduced.

When Fe is in the above range, the strength and elastic modulus are increased, and the coefficient of linear expansion is reduced. Fe is 1.0
If it is less than 5%, sufficient strength cannot be obtained, and if it is 5.0% or more, the effect on strength tends to be saturated, and machinability, extrudability, forgeability and the like are reduced. In addition,
Aluminum alloy A contains Cu 0.4% or more and less than 5.0% other than Si and Fe, Mg 0.2% or more and less than 2.0%, Mn
0.1% or more and less than 1.0% may be contained.

Cu enhances the fatigue strength from room temperature to high temperature by forming a solid solution and an S ′ phase (Al ₂ CuMg intermediate phase) in the aluminum alloy A, but 0.5% or more in the aluminum alloy A It is important that the content is less than 5.0%. If the Cu content is less than 0.4%, the above-mentioned fatigue strength is insufficient, and if it is 5.0% or more, the toughness at room temperature decreases.

Mg shows the same tendency as Cu. When the amount of Mg in the aluminum alloy A increases, the fatigue strength from normal temperature to high temperature increases, but the aluminum alloy A contains 0.2% to 2.0%. It is important that it be contained in a range of less than%.
If the Mg content is less than 0.2%, the fatigue strength becomes insufficient,
If it is 2.0% or more, the toughness at room temperature decreases. Mn has the effect of increasing the strength, but if it is less than 0.1%, the effect cannot be confirmed, and if it is 1.0% or more, the extrudability, forgeability, etc. decrease.

The Al—Fe-based aluminum alloy B (hereinafter simply referred to as aluminum alloy B) is obtained by rapidly solidifying a molten metal by a gas atomizing method or the like, and contains Fe in a range of 5.0% or more and less than 10.0%. Is important. When Fe is in this range, thermally stable A
It constitutes an l-Fe intermetallic compound, which is finely dispersed in a matrix to increase the room-temperature strength and high-temperature strength, increase the elastic modulus, and further reduce the linear expansion coefficient. Fe
If it is less than 5.0%, the effect of improving the strength at room temperature and high temperature is small, and if it is 10.0% or more, ductility and toughness are reduced, and it is not practical.

The aluminum alloy B is composed of Zr, V, Mo,
One or more of Cr, the total of which is 1.0% or more and 6.0 or more;
% May be contained. A part of one or more metal elements of Zr, V, Mo, and Cr is replaced with a part of Fe of the Al-Fe intermetallic compound to enhance the thermal stability of the Al-Fe intermetallic compound. In addition, the other part is Al-Zr-based,
It is dispersed as an Al-V-based, Al-Mo-based, or Al-Cr-based intermetallic compound and enhances room-temperature strength and high-temperature strength. Particularly, the contribution to the high-temperature strength is large. When the total of Zr, V, Mo, and Cr is less than 1.0%, the effect of improving the room temperature and high temperature strength is small, and when the total is more than 6.0%, the ductility and toughness are reduced. The melting point of the alloy B is rapidly raised to make the melting operation difficult.

The aluminum alloy A is formed by distributing the aluminum alloy B therein, that is, in the phase of the aluminum alloy B constituting the mixed phase, the particle diameter of the particles hardly increases even at the high temperature described above, and Al ₃ Fe, A with high high-temperature strength
Al Fe-based intermetallic compounds such as l ₆ Fe have an average particle size of 0.
By dispersing at 2 μm to 2.0 μm, the strength at around 200 ° C. is increased as compared with the case of the single use, but the strength at around 150 ° C. is reduced. Ductility and toughness are improved irrespective of temperature. It is important that the mixing ratio, B / (A + B), in the mixed phase of the aluminum alloy A and the aluminum alloy B is 0.1 to less than 0.4. When the mixing ratio of the aluminum alloy B is less than 0.1, the improvement in the high-temperature strength is insufficient, and when it is 0.4 or more, the strength is greatly reduced to 150 ° C., which impairs the normal-temperature strength.

The heat-resistant aluminum alloy having the above structure and excellent strength and toughness is an Al—S alloy containing at least 15% to less than 30% of Si and 1.0% to less than 5.0% of Fe.
rapidly solidified powder of i-Fe-based aluminum alloy A and Al containing at least 5.0% or more and less than 10.0% of Fe
It is manufactured by mixing a rapidly solidified powder of an Fe-based aluminum alloy B at a predetermined ratio, subjecting the mixed powder to degassing treatment, and then solidifying and molding.

First, the Al-Si-Fe-based aluminum alloy A of the above component is melted, the melt is atomized, and the fine droplets are solidified as they are to obtain a rapidly solidified powder. Similarly, a rapidly solidified powder is obtained for the Al-Fe-based aluminum alloy B of the above component. Since the particle size of the rapidly solidified powder of these aluminum alloys A and B is preferably fine in order to obtain high strength and high toughness, the coarse powder is removed by a sieve, and the average particle size is about 50 μm to 150 μm. Adjust to

Next, the rapidly solidified powders of these aluminum alloys A and B are mixed at a predetermined ratio, that is, at a mixing weight ratio of B / (A +) by a pulverizer such as a stirring mixer or a ball mill.
B) is mixed at 0.1 or more and less than 0.4, and the moisture or gas adsorbed on the mixed powder is degassed. This degassing treatment is performed by filling a can with the mixed powder and heating at 400 ° C to 500 ° C.
C., or by heating the preformed body obtained by cold-pressing the mixed powder to 400 to 500.degree. C. in an inert atmosphere or vacuum. The higher the temperature, the better the degassing effect, but when the high temperature is maintained for a long time, the Al-F
Since the particle size of the e-based intermetallic compound becomes coarse and adversely affects the strength, desirably, the temperature is 420 to 460 ° C for 15 minutes to 2 hours.
It is better to keep time.

After degassing, the mixed powder is densified to 100% by hot extrusion or hot pressing at 300 to 500 ° C. This step is also desirably performed at 420 ° C. or lower in order to suppress the grain size of the Al—Fe-based intermetallic compound from being increased. Next, the can filled with the mixed powder is removed to obtain a mixed preform, which is forged or cut as necessary to obtain a product.

The heat-resistant aluminum alloy having excellent strength and toughness is produced by a spray forming method other than the powder metallurgy method. That is, at least Si
Gas atomization is performed on a melt of an Al-Si-Fe-based aluminum alloy A containing 15% or more and less than 30% and Fe 1.0% or more and less than 5.0% to deposit fine alloy A droplets in a semi-solid state. A rapidly solidified body is obtained by spraying a predetermined amount of a rapidly solidified powder of an Al-Fe-based aluminum alloy B containing at least 5.0% or more and less than 10.0% on a deposition surface of the rapidly solidified body to form a mixed preform. The mixed preform is also manufactured by plastic working.

According to the spray forming method, first, the aluminum alloy A is melted, and the liquidus temperature of the aluminum alloy A is kept in a range of + 50 ° C. to + 150 ° C., and the aluminum alloy A is formed by a gas atomizing method or the like. Into fine droplets,
Droplets are deposited and deposited in a semi-solid state on the collector while being rapidly cooled to obtain a rapidly solidified body of the aluminum alloy A. Here, the gas used in the gas atomization method is an inert gas such as nitrogen or argon, which prevents oxidation of the molten metal and obtains a rapidly solidified solid having a relative density close to 100%. Gas volume is 2-8Nm ³ (G) per 1kg (M) of molten metal
(G / M ratio: 2 to 8).

The position of the collector to be deposited is lowered by an amount corresponding to the amount deposited, while rotating the collector 2 to 5 times per second in order to make the deposited layer uniform, thereby obtaining a cylindrical preform. At this time, as in the case of the aluminum alloy A, a rapidly solidified powder (B) produced by manufacturing an aluminum alloy B by a gas atomizing method or the like is sprayed onto the deposition surface of the rapidly solidified aluminum alloy A, thereby rapidly cooling the aluminum alloy A. Since it is taken in the solid deposition surface and deposited at the same time, the above-mentioned cylindrical mixed preform can be obtained. The jetting of the rapidly solidified powder of the aluminum alloy B is performed by providing an atomizing nozzle of the aluminum alloy B near the atomizing nozzle of the aluminum alloy A and injecting the rapidly solidified powder (B) into the atomized gas of the aluminum alloy A. In any case, the mixing weight ratio is such that B / (A + B) is 0.1 or more and less than 0.4.

Subsequently, the 0 in the mixed preform is
In order to crush the voids of up to several% and to strengthen the bond between the deposited layers, plastic working that also serves as a product shape, for example,
Hot extrusion, hot pressing, rolling, or forging, or a combination thereof is performed to obtain a product.

[0024]

EXAMPLES Examples of the present invention will be described below, and effects will be demonstrated based on the examples. It should be noted that these examples are for describing a preferred embodiment of the present invention, and the present invention is not limited thereto.

Examples 1-4 First, Si: 17.0%, Fe: 3.0%, Cu: 3.0%.
The molten aluminum (A) containing 0% and 1.0% of Mg and containing the balance of Al and impurities was kept at 820 ° C., and the molten aluminum (A) was subjected to nitrogen gas spraying according to the spray forming method. Atomized by (G
/ M ratio 3.3), the droplets were deposited on a rotating collector.

At this time, Fe:
8.0%, V: 2.0%, Mo: 1.0%, Zr: 1.
Al-F containing 0%, the balance being Al and impurities
The rapidly solidified powder of the e-based aluminum alloy B was mixed at the ratios shown in Examples 1 to 4 in Table 1 and simultaneously deposited to obtain a cylindrical mixed preform. The structure of the preform is not a fusion of the alloy A and the alloy B, but presents a state in which a spherical alloy B is mixed in the alloy A as shown in FIG. 1 (Example 3). The dimensions of the mixed preform are 160
The rapidly solidified powder of the Al-Fe-based aluminum alloy B having a diameter of 500 mm and a length of 500 mm was produced by a nitrogen gas atomizing method and classified to 300 μm or less, and had an average particle diameter of 50 μm.

Next, the unsteady deposition portions at both the upper and lower ends of the mixed preform were cut to form a 400 mm long billet.
Hot extrusion was performed on a round bar having a diameter of 30 mm at 00 ° C., followed by heating at 480 ° C. for 0.5 hour after hot extrusion, water cooling, and heat treatment at 180 ° C. for 4.0 hours, followed by air cooling. The structure after hot extrusion is shown in FIG. 2 (Example 3).

The hot-extruded round bars having a diameter of 30 mm obtained in Examples 1 to 4 were subjected to a tensile test at room temperature and at a temperature of 200 ° C. The tensile test at 200 ° C.
Performed after preheating for hours. The mixing ratios of Examples 1 to 4 were calculated by measuring the amount of Si in a hot-extruded round bar having a diameter of 30 mm.

Comparative Examples 1-3 Al-Si-Fe-based aluminum alloys A shown in Examples 1 to 4 in Table 1 were compared with rapidly solidified powders of Al-Fe-based aluminum alloys B shown in Examples 1 to 4. Except for mixing at the ratios shown in Examples 1 to 3, round bars having a diameter of 30 mm were manufactured under the same conditions as in Examples 1 to 4, and a tensile test was conducted at room temperature and 200 ° C. under the same conditions. Table 1 shows the measurement results.

[0030]

[Table 1]

According to Table 1, Examples 1 to 4 according to the present invention are shown.
, A good product having large strength and elongation at normal temperature and 200 ° C. was obtained. On the other hand, in Comparative Example 1, the elongation at room temperature was as small as 1%, and the high-temperature strength was low. Comparative Example 2 also has the same tendency as Comparative Example 1, and Comparative Example 3 has low room temperature strength.

Examples 5 to 13 Al-Si-Fe-based aluminum alloy A and Al-Fe
The system aluminum alloy B was set to the component values shown in Examples 5 to 13 in Table 2, and a hot extruded round bar was manufactured in the same manner as in Examples 1 to 4. At that time, the amount of molten aluminum alloy A is 8kg
/ Min, the powder addition amount of the aluminum alloy B is set to 2 kg / min, the mixing ratio of the aluminum alloy B is 0.2, the spray is nitrogen gas, the G / M ratio is 3.5, The powder was classified to 500 μm or less to obtain a nitrogen gas atomized powder (average particle size: 90 μm). The same measurement as in Examples 1 to 4 was performed on the obtained hot extruded round bar.

Comparative Examples 4 to 11 Al-Si-Fe Aluminum Alloy A and Al-Fe
The aluminum alloy B was set to the component values shown in Comparative Examples 4 to 11 of Table 2, and a hot-extruded round bar was manufactured in the same manner as in Examples 5 to 13. ~
The same measurement as in Example 13 was performed. Table 3 shows the measurement results.

[0034]

[Table 2]

[0035]

[Table 3]

According to Table 3, Examples 5 to 1 according to the present invention are shown.
No. 3 is a proof stress of 400 MPa or more and a tensile strength of 48 at room temperature.
0 MPa or more and elongation of 2.0% or more, and at a high temperature of 200 ° C., proof stress of 230 MPa or more and tensile strength of 250 MPa
As described above, a good product was obtained with an elongation of 8.0% or more.

On the other hand, in Comparative Example 4, the strength at 200 ° C. is low because the Fe content of the aluminum alloy B is low, and in Comparative Example 5, the elongation at room temperature is low because the Fe content of the aluminum alloy B is high. Comparative Example 6 has a low strength at 200 ° C. due to the low Zr + V + Mo + Cr content of the aluminum alloy B, and Comparative Example 7 has an aluminum alloy A
, Extruded cracks were severe due to the high Si content, and a hot extruded round bar could not be obtained.

Comparative Example 8 has a low Fe at room temperature due to the high Fe content of the aluminum alloy A, Comparative Example 9 has a low strength at normal temperature due to the low Cu content of the aluminum alloy A, and Comparative Example 10 has a low strength at normal temperature. , The elongation at room temperature is low. In Comparative Example 11, the elongation at room temperature is low because the Mg content of the aluminum alloy A is high.

Example 14 A heat-resistant aluminum alloy was manufactured by a powder alloying method for aluminum alloy A and aluminum alloy B at substantially the same mixing ratio as in example 3. That is, a nitrogen gas atomized powder of the aluminum alloy A and a nitrogen gas atomized powder of the aluminum alloy B (both classified to 300 μm or less and having an average particle size of 80 μm) are mixed at a mixing ratio of 7: 3, and have a diameter of 155 mm and a length of 50 μm.
A 0 mm container made of a 6063-based aluminum alloy was filled.

Next, a degassing treatment was performed by keeping the inside of the container under vacuum at 430 ° C. for 1 hour, and the mixed powder was sealed in the container.
This was hot-extruded into a round bar having a diameter of 30 mm at 400 ° C. as a billet, heated at 480 ° C. for 0.5 hour after hot extrusion, water-cooled, heat-treated at 180 ° C. for 4.0 hours, and air-cooled. The same measurement as in Examples 1 to 4 was performed on the obtained round bar. Table 4 shows the measurement results.

[0041]

[Table 4]

According to Table 4, the measured values of Example 14 were almost the same as those of Example 3, and no significant difference due to the difference in the manufacturing method was observed.

[0043]

According to the present invention, at least Si 15%
Al-Si-Fe-based aluminum alloy A containing not less than 30% and less than 1.0% Fe and less than 5.0%, and Al-Si containing at least 5.0% or more and less than 10.0% Fe.
Fe / aluminum alloy B is mixed with B /
By making (A + B) 0.1 or more and less than 0.4, Al
-Fe-based intermetallic compound is formed and aluminum alloy A
A matrix property in which a spherical Al-Fe-based intermetallic compound is mixed in a dispersed state is obtained, so that high strength can be maintained even at a high temperature and toughness is excellent.

[Brief description of the drawings]

FIG. 1 is a photomicrograph showing the structure of a preform during the production of a heat-resistant aluminum alloy of the present invention.

FIG. 2 is a micrograph showing a structure after hot extrusion of a preform.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22F 3/17 C22C 21/02 C22C 1/04 B22F 3/02 P 21/02 101C (72) Inventor Naoki Jitsu 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. F term (reference) 4K018 AA16 BC12 GA01 KA07

Claims (7)

[Claims] 1. An Al—Si—Fe-based aluminum alloy A containing at least 15% to less than 30% of Si (% by weight, the same applies hereinafter) and 1.0% to less than 5.0% of Fe, and at least 5.0% of Fe Al containing less than 10.0%
-A heat-resistant aluminum alloy having excellent strength and toughness, comprising a mixed phase with Fe-based aluminum alloy B, wherein the mixed weight ratio B / (A + B) is 0.1 or more and less than 0.4. 2. Al-F constituting the mixed phase according to claim 1.
In the phase of e-type aluminum alloy B, the average particle size is 0.2 μm
A heat-resistant aluminum alloy excellent in strength and toughness, characterized in that an Al-Fe-based intermetallic compound of up to 2.0 µm is dispersed. 3. The Al-Si-Fe-based aluminum alloy A contains Cu 0.4% or more and less than 5.0%, Mg 0.2% or more and less than 2.0%, and Mn 0.1% or more and less than 1.0%. 3. The heat-resistant aluminum alloy according to claim 1, wherein the heat-resistant aluminum alloy has excellent strength and toughness. 4. The Al-Fe-based aluminum alloy B,
4. Excellent in strength and toughness according to claim 1, 2 or 3, wherein one or more of Zr, V, Mo, and Cr contain 1.0% or more and less than 6.0% of the total thereof. Heat resistant aluminum alloy. 5. The Al—Si—Fe based aluminum alloy A and the Al—Fe based aluminum alloy B are rapidly solidified alloys.
A heat-resistant aluminum alloy having the strength and toughness described. 6. At least 15% or more and less than 30% of Si,
Al-Si-F containing 1.0% or more and less than 5.0%
e-type aluminum alloy A rapidly solidified powder and Al-Fe containing at least 5.0% or more and less than 10.0%
A method for producing a heat-resistant aluminum alloy having excellent strength and toughness, comprising mixing a rapidly solidified powder of a system aluminum alloy B with a predetermined ratio, subjecting the mixed powder to degassing treatment, and then solidifying the mixed powder. . 7. At least 15% or more and less than 30% of Si,
Al-Si-F containing 1.0% or more and less than 5.0%
e-Aluminum melt is gas-atomized, and finely divided droplets of alloy A are deposited in a semi-solid state to form a rapidly solidified body, and the rapidly solidified body contains at least 5.0% or more and less than 10.0% Fe. Manufacturing a heat-resistant aluminum alloy excellent in strength and toughness, characterized in that a predetermined amount of rapidly solidified powder of an Al-Fe-based aluminum alloy B to be sprayed is sprayed to form a mixed preform, and the mixed preform is subjected to plastic working. Method.