JPH06158207A - High heat and wear resistance aluminum-based composite material - Google Patents

Abstract

PURPOSE:To ensure high heat and wear resistance by producing a heat resistant Al alloy contg. Ni, Si, Mg, Fe, Cu, Al, nitride and boride in specified conditions by a powder metallurgical processing. CONSTITUTION:A heat resistant Al alloy consisting of, by weight, 10-20% Ni, 8-25% Si, <=10% in total, of at least one of 0.6-8% Fe and 0.6-5% Cu and the balance Al and not practically contg. Mg is used as a matrix. Particles of one or more among nitrides and borides are dispersed in the matrix by 0.5-10% per 100% of the resulting composite material contg. the matrix and the objective Al-based composite material is produced by the powder metallurgical processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is useful for application to engine parts of automobiles, aircrafts such as valve lifters, pistons, valve spring retainers, etc. Abrasion resistant aluminum matrix composites.

[0002]

2. Description of the Related Art Aluminum alloys have been used as structural materials for aircraft or automobiles for a long time because they are lightweight and have excellent workability. Among the conventional aluminum alloys, those having excellent heat resistance include JIS2024,
Al-Cu-Mg-based alloys such as 2018 are known.

An Al-Ni alloy containing 5% by weight or more of Ni (hereinafter simply referred to as "%") (sponsored by Japan Institute of Light Metals, A
l alloy powder metallurgy technology symposium (March 9, 1987)
(Held daily) Proposals, pages 58 and 70) are proposed. Similarly, JP-A-2-149629 and JP-A-2-14
9631, JP-A-2-149632, JP-A-2-1493
Japanese Patent No. 633 discloses "a low thermal expansion aluminum alloy excellent in wear resistance and thermal conductivity" which is made of an Al-Ni-Si-Cu-Mg-based alloy produced by a casting method and containing 8% or more of Ni. ing.

Further, Japanese Examined Patent Publication No. 2-56401 discloses Al-containing 7.7 to 15% Ni and 15 to 25% Si, and the size of Si crystal grains is 15 μm or less.
"Heat resistant and wear resistant high strength aluminum alloy powder" made of Ni-Si alloy powder is disclosed.

[0005]

The engine for automobiles is required to have a high output. Therefore, materials for engine parts such as valve lifters, pistons, and valve spring retainers are required to have a tensile strength of 200 MPa or more at 300 ° C. To be done. From this point of view, the above JIS 2024, 20
Al-Cu-Mg alloys such as 18 have excellent tensile strength at room temperature, but have a tensile strength of at most 3 at a high temperature of 200 ° C.
Tensile strength is 150MP at high temperature of 00MPa and 300 ℃
a, which is used for engine parts of recent automobiles and the like.
-Cu-Mg based alloy cannot be applied. Also,
Al-Ni alloy and Al-N described in the above proposal or publication
The i-Si-Cu-Mg-based alloy, a NiAl ₃ intermetallic compound produced in the tissue, although the heat resistance and wear resistance is improved, since the to produce a product by casting, the product The particle size of the NiAl ₃ intermetallic compound in Fig. 2 was as large as about 10 µm, and at most 380 M at room temperature
It was revealed that the tensile strength decreased to 160 MPa at high temperatures of Pa and 300 ° C. For this reason, it is difficult to apply such an aluminum alloy as an engine component for automobiles in recent years.

On the other hand, with the Al-Ni-Si alloy powder described in the above publication, a product is manufactured by a sintering method. That is, an alloy raw material having a constant composition is melted and sprayed to obtain the above Al-Ni-Si alloy powder, and this Al-Ni-
A product is obtained by cold preforming, extruding, and forging Si-based alloy powder. Therefore, this Al-Ni-Si
In Ni-based alloy powder, the particle size of NiAl ₃ intermetallic compound is 4μ.
The tensile strength is 510 MPa at room temperature and 345 MPa at 250 ° C., as well as being excellent in wear resistance. However, in general, engine parts such as automobiles may not have a sufficient extrusion ratio (the cross-sectional area ratio before and after extrusion).

MM in which ceramic particles and fibers are dispersed
C (metal-based composite material) generally has high high-temperature strength, but has low forgeability and elongation. When trying to improve the forgeability,
On the contrary, the high temperature strength decreases. Therefore, in order to achieve both high temperature strength and forgeability, it is necessary to select an appropriate matrix. The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide an aluminum-based composite material capable of producing a product excellent in stable wear resistance and particularly high temperature strength of 300 ° C or higher.

[0008]

The present inventors have found that an excellent heat-resistant aluminum alloy can be obtained by blending an aluminum alloy having high Ni and high Si with at least one of Fe and Cu. I proceeded with my research. Then, it was discovered and confirmed that Mg, which is always compounded in high Ni and high Si aluminum alloys containing at least one of Fe and Cu, has an unfavorable effect on room temperature strength and high temperature strength. And applied earlier as a heat resistant aluminum alloy. The present invention uses the above aluminum alloy as a matrix, and a metal matrix composite material in which nitride and boride particles are dispersed in the matrix has excellent strength and elongation at high temperature, and forging property and wear resistance are improved. It was discovered and confirmed.

The aluminum-based composite material of the present invention has a Ni: 1% by weight ratio when the matrix is 100% by weight.
0 to 20%, Si: 8 to 25%, and substantially Mg
And at least one of Fe: 0.6 to 8.0% and Cu: 0.6 to 5.0%, the total amount of the Fe and Cu is 10% or less, and the balance Is a heat-resistant aluminum alloy composed of Al as a matrix, and the total amount of the composite material containing the matrix is 100% by weight, one or more kinds of particles of nitride and boride are 0.5 to 10% by weight in total. It is characterized by being dispersed in a matrix and manufactured by a powder metallurgy method.

In the matrix constituting the aluminum-based composite material of the present invention, weight% (hereinafter,% means% by weight unless otherwise specified) and further Zr: 0.3 to.
It can contain 2.0%. This matrix is substantially free of Mg and contains a specific amount of Ni, Si, Fe, C.
It is formed of a heat-resistant aluminum alloy containing u.

This aluminum-based composite material is a mixed powder obtained by uniformly mixing fine powders of nitride and boride with fine powders produced by melting and spraying a heat-resistant aluminum alloy constituting the matrix of the above composition. The mixed powder can be manufactured by a powder metallurgical method in which it is pressed and then sintered. Usually, this pressure-molded mixed powder is put in a case, and cold preforming (CIP) and hot extrusion forging are performed in this state.

The blending proportions and functions of the elements other than aluminum constituting the matrix of the heat resistant aluminum alloy of the present invention will be described below. In addition,% is 1 matrix
It is set to 00%. [Ni: 10 to 20%] Ni together with Al is NiA
Make an intermetallic compound such as l ₃ . These intermetallic compounds are stable even at high temperatures and contribute to the wear resistance and high temperature strength of the alloy. In particular, the NiAl ₃ intermetallic compound is lower in hardness and richer in toughness than other intermetallic compounds and the like.

By adding 5.7% or more of Ni,
Precipitation of NiAl ₃ intermetallic compound is observed in the obtained alloy, but when Ni is added less than 10%, the tensile strength of the obtained matrix at 300 ° C. does not exceed 200 MPa and the high temperature strength is effectively improved. do not do. Conversely, Ni is 4
If the addition amount is 0% or less, the resulting alloy forms a NiAl ₃ intermetallic compound, but if Ni is added in excess of 20%, the matrix becomes brittle and the elongation value at room temperature becomes extremely small. Therefore, when Ni is added in an amount of more than 20%, the product has excellent high-temperature strength and wear resistance, but the machinability and the like are remarkably inferior, which makes practical use difficult. [Si: 8-25%] The alloy in which fine Si is dispersed in Al is excellent in high temperature strength and wear resistance.
Known for alloys and the like.

When the product is manufactured by the casting method, S
Coarse Si for aluminum alloys containing 11.3% or more of i
The primary crystals crystallize, and such alloys attack the mating material of the sliding part, the machinability deteriorates significantly, the elongation of the alloy itself decreases significantly, and the production technology (for example, cracks during parts processing) Etc.) is not practical, and cracks may occur during use as parts, which is not preferable. However, in the case of producing a composite material using an aluminum alloy as a matrix by the rapid solidification powder metallurgy method, an aluminum alloy in which fine Si is crystallized can be obtained even if Si is mixed up to 25%. When Si is blended in an amount of more than 25%, coarse Si crystallizes in the product even when alloy powder is produced by the rapid solidification method, which is not preferable.

On the contrary, when the content of Si is less than 8%, the high temperature strength and wear resistance of the obtained matrix are insufficient. [Fe: 0.6 to 8.0%] In general, addition of Fe is not preferable, and even if it is contained, it is desirable that the content of Fe be 0.5% or less. It has been found that the addition of the compound improves the room temperature strength and the high temperature strength of 300 ° C. of the obtained matrix. Fe
Is less than 0.6%, the effect of improving the room temperature strength of the matrix and the high temperature strength of 300 ° C is small, and Fe is 8%.
If it is blended in excess of 10%, the matrix becomes brittle. However,
At least one kind of Fe and Cu described later is contained,
When the total amount of Fe and Cu is 10% or less, the room temperature strength of the matrix is effectively improved. [Cu: 0.6 to 5.0%] Cu imparts age hardening to the heat resistant aluminum alloy and strengthens the matrix. C
When u is added in an amount of 0.6% or more, it has an effect of improving the room temperature strength of the matrix, and when Cu is added in an amount of more than 5%, coarse crystallized substances are formed and the high temperature strength of the matrix at 300 ° C. is lowered. . However, if at least one of Cu and Fe is contained and the total amount of Fe and Cu is 10% or less, the room temperature strength of the matrix is effectively improved. [Mg: Substantially Free] Generally, Mg is the same as Cu.
Although it is known as a component that strengthens Al alloys, the experimental results of the inventors show that alloys containing Mg have room temperature strength and high-temperature strength and elongation at 300 ° C. as compared with alloys containing no Mg. Both were found to decrease.

In Japanese Patent Publication No. 63-20298, Al contains Ni and Si, and Cu and Mg.
Although it is described as an aluminum alloy containing at least one of the above, this publication does not include an example of an aluminum alloy containing no Cu but containing Mg. In addition, this publication describes Mg
There is no description that suggests that has an adverse effect on room temperature strength and high temperature strength. [Zr: 0.3 to 2.0%] Zr is known as an additive element that improves high temperature strength, but the experimental results of the inventors have shown that the elongation value of an aluminum alloy at room temperature and 300 ° C. It turned out to improve. That is, when Zr: 0.3 to 2.0% is added to the matrix of the present invention, the toughness of the matrix is effectively improved. If Zr is less than 0.3%, the effect of improving toughness is small, and Zr is 2.0%.
Coarse intermetallic compound (ZrAl ₃ )
Undesirably crystallizes out. [Ti: 1.0 to 4.0%] Ti is known as an additive element that improves the high temperature strength like Zr, but according to the experimental results of the inventors, the yield strength at 300 ° C. of the matrix is improved. It turned out to let me. Mixing ratio of Ti is 1.0
~ 4.0%. If the Ti content is less than 1.0%, the yield strength improvement effect at high temperatures is small, and if the Ti content is more than 4.0%, the toughness of the matrix decreases, which is not desirable. [Nitride, boride: 0.5 to 10% in total] The wear resistance of the aluminum-based composite material obtained by dispersing particles of nitride and boride in a matrix made of a heat-resistant aluminum alloy is improved. If the amount of this nitride or boride is less than 0.5%, the effect of addition is not recognized. On the other hand, if the amount added exceeds 10%, the tensile strength, elongation and machinability of the aluminum-based composite material are significantly deteriorated, which is not preferable.

As the nitride, for example, AlN, Ti
N, ZrN, BN, etc. are mentioned. As boride,
For example, TiB ₂ , NiB, MgB _{2 and the} like can be mentioned. The nitride and boride are preferably fine powder and have a thickness of 0.5 to 20 μm. If it is less than 0.5 μm, the powders agglomerate and the mechanical properties deteriorate. If it is larger than 20 μm, the particles are broken or fallen off during sliding, and the effect of improving wear resistance is reduced.

One or more of these nitrides and borides are mixed with the heat-resistant aluminum alloy having the above composition and treated by powder metallurgy to produce an aluminum-based composite material.

[0019]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Tables 1 and 2 together with comparative examples of examples embodying the present invention.

[0020]

[Table 1] The numbers before the elements of the composition shown in Table 1 are the matrix 100.
It is the amount of% in%. The numbers preceding the nitrides and borides indicate the% amounts, based on 100% of the total composite.

The molten aluminum matrix having the composition shown in Table 1 was pulverized by an atomizing method and then classified by a 100-mesh sieve, and the grain size of nitride and boride was 1 to 20.
A predetermined amount of fine powder of μm was mixed with the above matrix powder to obtain a mixed powder. In Comparative Examples 3 and 4, the average particle size is 2.6 μm.
Of SiC particles are mixed. The matrix of Comparative Example 3 is 2024, and the matrix of Comparative Example 4 is 6061.
Is a component corresponding to.

[0022]

[Table 2] TS: tensile strength (MPa), YP: yield strength (MP
a), δ: Elongation (%) Specific wear amount (mm ³ / kg · mm) These mixed powders are loaded into a tube with a bottom of pure Al, and cold preforming at a surface pressure of 3 ton / cm ² under vacuum conditions. Then
A preform of φ30 × L80 was manufactured. These preforms were heated at 450 ° C. for 30 minutes and hot extruded at a relatively large extrusion ratio “10” to obtain a rod-shaped aluminum-based composite material with a diameter of 10 mm. In each aluminum-based composite material of this example, nitride and boride particles are dispersed in a heat-resistant aluminum alloy matrix. [Evaluation] For each of the above aluminum-based composite materials and heat-resistant aluminum alloy samples, room temperature, 150 ° C., 300
The strength characteristics were measured at ° C. Table 2 shows the measured tensile strength, yield strength and elongation.

From Table 2, it can be seen that the aluminum-based composite materials of Examples 1 to 4 and Comparative Examples 1 to 2 each have a tensile strength at room temperature (RT) of more than 500 MPa and a tensile strength at 300 ° C. of more than 200 MPa. ,
It turns out to be excellent. The aluminum alloy of Comparative Example 1 has the same composition as the aluminum alloy forming the matrix of Examples 1 and 3, and the aluminum alloy of Comparative Example 2 includes the aluminum alloy forming the matrix of Examples 2 and 4. It has the same composition. Therefore, in terms of strength, it is almost the same as the heat-resistant aluminum alloy of the matrix, and no adverse effect due to the addition of the nitride or boride is recognized.

The aluminum-based composite materials of Comparative Examples 3 to 4 were
Although the tensile strength at room temperature is around 500 MPa, it is 30
At 0 ° C, the tensile strength is reduced to around 100 MPa.
This is because the aluminum alloy matrix originally has low high temperature strength. Further, since SiC was not compatible with the matrix and cracks were easily generated and propagated at the grain interface, there was almost no elongation, and therefore the yield strength could not be measured.

Next, wear tests were conducted on the aluminum-based composite materials of Examples 1 to 4 and the aluminum alloys of Comparative Examples 1 to 4. The amount of wear was measured under the test conditions in which a ring-shaped mating member immersed in oil was SUJ2 using an LFW tester, and a test piece was pressed against this with a load of 150 N, a time of 15 minutes, and a sliding speed of 18 m / min. From Table 2, the aluminum-based composite materials of Examples 1 to 4 are comparative examples 1 to 2.
It can be seen that the specific wear amount is smaller and the wear resistance is excellent in comparison with the aluminum alloy of. The wear resistance of Comparative Examples 3 and 4 is considerably excellent, but it is 300
Remarkably low tensile strength (TS) at ° C.

In addition, in the aluminum-based composite material to which the nitride was added in the LFW test, aluminum was less transferred to the mating material. Furthermore, in the aluminum-based composite material to which boride is added, B in boride becomes 1 part B ₂ O ₃ , and this B ₂ O ₃ becomes a liquid phase (mp 450 ° C.) during friction and becomes a fluid lubricant and wears. It is estimated that the sexuality has improved. Figure 1
3 is an enlarged photograph of the metal structure of Example 1, as shown in FIG. As shown in FIG. 1, the AlN additive particles are intimately contacted and dispersed without forming pores or the like at the interface of the matrix. FIG. 2 shows the metal structure of the aluminum alloy of Comparative Example 1, which is uniform.

Therefore, according to the above evaluation, Example 1
The aluminum-based composite material produced by sintering the aluminum-based composite material powders of Nos. 4 to 4 is lightweight, has excellent wear resistance, rigidity, thermal expansion characteristics, and tensile strength at room temperature, and has a high temperature of 300 ° C. Has a tensile strength of 20
It can be seen that the yield strength is 0 MPa or more and the yield strength is 180 MPa or more.

[0028]

As described in detail above, the aluminum-based composite material of the present invention uses a heat-resistant aluminum alloy containing a predetermined amount of Ni, Si, Fe, Cu and containing no Mg as a matrix. Since it is lightweight, it has excellent wear resistance because it has nitride and boride particles dispersed, and has strength almost similar to that of a heat-resistant aluminum alloy in which nitride and boride particles are not dispersed. .

Therefore, even if engine parts such as automobiles are manufactured with the heat resistant aluminum alloy of the present invention, the heat resistant aluminum alloy is lightweight and has stable wear resistance, rigidity, thermal expansion characteristics, room temperature strength and Since it can exhibit high-temperature strength, it becomes an engine component that can reliably meet the recent demand for higher output.

[Brief description of drawings]

FIG. 1 is an 800 × magnified micrograph showing the metal structure of Example 1.

FIG. 2 is an 800 × magnified micrograph showing the metal structure of Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohisa Miura 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Yasuhiro Yamada 1, Toyota Town, Aichi Prefecture, Toyota Motor Co., Ltd. ( 72) Inventor Hirofumi Michioka 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Jun Kusunii 3-6-8, Kutaro-cho, Chuo-ku, Osaka Toyo Aluminum Co., Ltd. (72) Invention Aki Tanaka, 3-6-8, Kutaro-cho, Chuo-ku, Osaka City Toyo Aluminum Co., Ltd.

Claims (3)

[Claims] 1. A matrix containing 100% by weight of Ni: 10 to 20% and Si: 8 to 25% by weight, substantially free of Mg, and at least Fe:
A heat-resistant aluminum alloy containing 0.6 to 8.0% and Cu: 0.6 to 5.0%, the total amount of the Fe and Cu is 10% or less, and the balance being Al. Matrix and the whole composite material containing the matrix is 1
It is characterized in that one or two or more kinds of particles of nitrides and borides are dispersed in the matrix in a total amount of 0.5 to 10% by weight when the amount is 00% by weight, and the particles are manufactured by powder metallurgy. Heat resistant and high wear resistant aluminum matrix composite material. 2. The matrix is 100% by weight when the matrix is 100% by weight, and further Zr: 0.3-2.
The high heat resistance and high wear resistance aluminum matrix composite material according to claim 1, containing 0%. 3. When the matrix is 100 wt%, the matrix is wt%, and Ti: 1.0 to 4.
The high heat resistance and high wear resistance aluminum matrix composite material according to claim 1, containing 0%.