JP3139649B2 - High heat and wear resistant aluminum-based composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve spring having excellent toughness, abrasion resistance, high temperature strength and creep resistance, which is useful when applied to engine parts for automobiles, aircraft, etc., such as valve spring retainers, intake valves, and pistons. The present invention relates to a heat-resistant and highly wear-resistant aluminum-based composite material.

[0002]

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

An Al—Ni alloy containing 5% by weight or more (hereinafter simply referred to as “%”) of Ni (sponsored by the Japan Institute of Light Metals, A
Symposium on Powder Metallurgy for Alloy 1 (March 9, 1987)
Proceedings, p. 58, p. 70) have been proposed. Similarly, JP-A-2-149629 and JP-A-2-14
9631, JP-A-2-149632, JP-A-2-149
No. 633 discloses a "low thermal expansion aluminum alloy having excellent wear resistance and thermal conductivity" comprising an Al-Ni-Si-Cu-Mg based alloy containing 8% or more of Ni and manufactured by a casting method. ing.

Further, Japanese Patent Publication No. 2-56401 discloses an Al-containing alloy containing 7.7 to 15% of Ni and 15 to 25% of Si and having a Si crystal grain size of 15 μm or less.
A "heat- and wear-resistant high-strength aluminum alloy powder" comprising a Ni-Si-based alloy powder is disclosed.

[0005]

A high output is required for an automobile engine. For this reason, a material for an engine part such as an intake valve has a tensile strength of 200 ° C. at 300 ° C.
Mpa or more is required. From this viewpoint, the above JI
Al-Cu-Mg based alloys such as S2024 and 2018
Although the tensile strength at room temperature is excellent, the tensile strength at a high temperature of 200 ° C is at most 300 MPa, and the tensile strength at a high temperature of 300 ° C is 150 MPa, and these Al-Cu-Mg alloys are applied to engine parts such as automobiles in recent years. I can't. In addition, the above Al-Ni alloy and Al-N
In the i-Si-Cu-Mg-based alloy, although the heat resistance and wear resistance are improved by the NiAl ₃ intermetallic compound generated in the structure, the product is manufactured by a casting method. The particle size of the NiAl ₃ intermetallic compound in Example 1 was as large as about 10 μm, and was at most 380 M at room temperature.
At a high temperature of Pa and 300 ° C., it was found that the tensile strength decreased to 160 MPa. For this reason, it is difficult to apply even such an aluminum alloy as an engine part of a recent automobile or the like.

On the other hand, with the above Al-Ni-Si alloy powder, a product is manufactured by a sintering method. That is, an alloy material having a constant composition is melted and sprayed to form the Al-N
An i-Si alloy powder is obtained, and a product is obtained by cold preforming, extruding, and forging the Al-Ni-Si alloy powder. For this reason, in this Al-Ni-Si alloy powder, the particle size of the NiAl ₃ intermetallic compound is 4 μm or less, which is excellent in abrasion resistance and has a tensile strength of 51 μm at room temperature.
345 MPa is obtained at 0 MPa and 250 ° C. However, in general, there are cases where a sufficient extrusion ratio (cross-sectional area ratio before and after extrusion) cannot be obtained with engine parts such as automobiles.

MM in which ceramic particles and fibers are dispersed
C (metal-based composite material) generally has high high-temperature strength, but low forgeability and elongation. Also, when trying to improve forgeability,
Conversely, the high temperature strength decreases. 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-described conventional circumstances, and provides an aluminum-based composite material capable of producing a product excellent in forgeability, stable wear resistance, and particularly, tensile strength at high temperatures and yield strength. With the goal.

[0008]

Means for Solving the Problems The present inventor has found that an excellent heat-resistant aluminum alloy can be obtained by blending Fe and Cu with an aluminum alloy of high Ni and high Si, and has conducted research on such alloys. . A metal matrix composite material in which an aluminum alloy having a specific composition ratio is used as a matrix and nitride and boride particles are dispersed therein has excellent tensile strength and elongation at high temperatures, high forgeability and high wear resistance. It was discovered and confirmed.

The aluminum-based composite material of the present invention has a Ni: 2 ratio by weight of 100% by weight of the matrix.
-15%, Si: 0.2-15%, Fe: 0.6-8.
0%, Cu: 0.6 to 5.0%, and Mg: 0.5 to
3% (however, Cu + Mg ≦ 6%) and Zr: 0.3 to 3
% And Mo: 0.3 to 3% (however, Zr + Mo ≦ 4
%), And the remainder is made of a heat-resistant aluminum alloy composed of unavoidable impurities and Al as a matrix, and a nitride when the entire composite material containing the matrix is 100% by weight;
One or more of the boride particles is 0.5 to 1 in total.
0% by weight is dispersed in the matrix, and is manufactured by a powder metallurgy method.

In the matrix constituting the aluminum-based composite material of the present invention, Ti: 0.5 to 4.0 by weight% (hereinafter, unless otherwise specified,% means weight%).
%. This aluminum-based composite material is prepared by melting and spraying a heat-resistant aluminum alloy constituting a matrix having the above composition, into fine powder, nitride,
It can be manufactured by a powder metallurgy method in which a boride fine powder is uniformly mixed to form a mixed powder, and the mixed powder is subjected to pressure molding and then sintered. Usually, this mixed powder is put in a case, and in this state, cold preforming (CIP or the like) and hot extrusion are performed.

The mixing ratio and action of 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 for the matrix.
00%. [Ni: 2 to 15%] Ni is, together with Al, NiAl
Create an intermetallic compound such as 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, NiAl ₃ intermetallic compounds have lower hardness,
Richer in toughness.

For this reason, it is necessary to add 2% or more of Ni as a matrix hardening agent for ensuring high-temperature strength. If the Ni content exceeds 15%, the high-temperature strength of the matrix can be ensured, but the precipitation of coarse crystals deteriorates the workability and elongation, which deteriorates the forgeability. [Si: 0.2 to 15%] An alloy in which fine Si is dispersed in Al has excellent high-temperature strength and wear resistance.
90 alloy and the like.

When producing a composite material using an aluminum alloy as a matrix by a rapid solidification powder metallurgy method,
If Si is added in excess of 15%, coarse primary crystal Si crystallizes out of the product even when an alloy powder is produced by the rapid solidification method, which is not preferable. If the amount of Si is less than 0.2%, the effect of addition is not recognized, which is not preferable. [Fe: 0.6 to 8.0%] In general, it is considered that the addition of Fe is not preferable, and even if it is contained, it is desirably 0.5% or less. However, the experimental results of the inventors have revealed that the room temperature strength and the high temperature strength at 300 ° C. of the obtained matrix are improved by adding Fe. When Fe is less than 0.6%, the effect of improving the ordinary temperature strength of the matrix and the high temperature strength at 300 ° C. is small, and when Fe is more than 8%, the matrix becomes brittle.

[Cu: 0.6-5.0%] Cu imparts age hardening to the heat-resistant aluminum alloy and strengthens the matrix. When the content of Cu is 0.6% or more, there is hardening for improving the room-temperature strength of the matrix. When the content of Cu exceeds 5%, coarse crystals are formed and the high-temperature strength of the matrix is reduced. Note that Cu and M
If the total amount of g is 6% or less, the forgeability of the matrix can be maintained.

[Mg: 0.5 to 3.0%] Generally, Mg is known as a component for strengthening an Al alloy like Cu. If the amount of Mg exceeds 3%, a coarse compound is precipitated and forgeability is deteriorated, which is not preferable. However, as described above, when the total amount of Cu and Mg is 6% or less,
If so, the effect of addition can be maintained.

[Zr: 0.3-3.0%] Zr is a high temperature
Known as an additive to improve strength and creep resistance
Have been. That is, Zr: 0.3 was added to the matrix of the present invention.
-3.0% is effective for matrix toughness
To improve. Addition of less than 0.3% of Zr improves toughness.
Less effect, coarser if Zr exceeds 3.0%
Intermetallic compounds (ZrAl _Three) Crystallize and
No.

[Mo: 0.3 to 3.0%] Like Mo, Mo is also an element which can improve heat resistance with the same amount of addition, but in the present invention, Mo is replaced by Zr and Mo.
The forging property and the creep resistance can be secured by adding such that the total amount thereof is 4% or less . total
If the amount exceeds 4%, the forgeability is rather reduced, so it is preferable.
Not good.

[Ti: 0.5-4.0%] Ti is Zr
Similarly, it is known as an additive element for improving the high-temperature strength, but according to the experimental results of the present inventors, the matrix at 300 ° C.
It has been found that the yield strength in steel is improved. The compounding ratio of Ti is 0.5 to 4.0%. 0.5% Ti
If it is less than 10%, the effect of improving the yield strength at high temperatures is small, and T
Addition of more than 4.0% i is undesirable because it reduces the toughness of the matrix.

[Nitride, boride: 0.5 to 10 in total
%] The wear resistance of an aluminum-based composite material obtained by dispersing nitride and boride particles in a matrix made of a heat-resistant aluminum alloy is improved. This nitride,
If the amount of boride is less than 0.5%, the effect of wear resistance due to the addition is not recognized. If the amount exceeds 10%, the tensile strength, elongation, and machinability of the aluminum-based composite material are unpreferably reduced.

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

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

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples which embody the present invention. Tables 1 and 2 show the compositions of Examples and Comparative Examples, and Tables 3 and 4 show the characteristic values. The numbers in front of the elements having the compositions shown in the matrix composition columns in Tables 1 and 2 are 100% matrix.
It is the percentage of the element in it. The numbers preceding the respective nitrides and borides in the nitride and boride column indicate the percentage of nitrides and borides based on 100% of the total composite.

A powder of a molten Al matrix having a composition shown in Table 1 was powderized by an atomizing method, classified by a 100-mesh sieve, and a predetermined amount of a fine powder of nitride or boride having a particle size of 1 to 20 μm was added thereto. To obtain a mixed powder. These mixed powders were loaded into a tube with pure Al bottom and cold preformed under a vacuum condition at a surface pressure of 3 ton / cm ² to produce a preform of φ30 mm × L80 mm. These preforms were placed at 450 ° C for 30
After heating for 1 minute, hot extrusion was performed at a relatively large extrusion ratio "10" to obtain 9 kinds of aluminum-based composite materials No. 1 to 9 shown in Table 1 having a diameter of 10 mm. In each of the aluminum-based composite materials of these examples, nitride and boride particles are dispersed in a heat-resistant aluminum alloy matrix.

[0024]

[Table 1] After pulverizing a melt of an aluminum alloy having a composition of No. 51, No. 52, No. 57 and No. 58 shown in Table 2 by an atomizing method, it was classified by a 100-mesh sieve to obtain an aluminum alloy powder. No53, No54,
No. 55 was prepared by pulverizing a molten Al matrix having a composition shown in Table 2 by an atomizing method, and then classifying the powder with a 100-mesh sieve. A fine powder of a nitride or boride having a particle size of 1 to 20 μm was added in a predetermined amount. The mixture was mixed with the matrix powder to obtain a mixed powder. No. 56 was prepared by pulverizing a molten Al matrix having the composition shown in Table 2 by an atomizing method, and then classifying the powder using a 100-mesh sieve. Then, 15% of a fine powder of silicon carbide having a particle size of 2.6 μm was mixed with the mixed powder by 15%. And

Each of these mixed powders was loaded into a tube with pure Al bottom and cold preformed under a vacuum condition at a surface pressure of 3 ton / cm ² to produce a preform of φ30 mm × L80 mm. These preforms were placed at 450 ° C for 30
For 5 minutes and hot extrusion was performed at a relatively large extrusion ratio of “10”.
Thus, eight types of aluminum-based composite materials and aluminum alloys were obtained.

[0026]

[Table 2]

[0027]

[Table 3] σ: tensile strength (MPa), YP: yield strength (MPa),
δ: Elongation (%) Specific wear (mm ³ / kg · mm), Critical upsetting rate (%) “-” is almost 0 and cannot be measured, blank is not measured

[0028]

[Table 4] σ: tensile strength (MPa), YP: yield strength (MPa),
δ: Elongation (%) Specific wear amount (mm ³ / kg · mm), Critical upsetting rate (%) “-” is almost 0 and cannot be measured, and blank column indicates unmeasured. For the samples of the aluminum-based composite materials No. 1 to No. 9 of the examples, the tensile strength and elongation at room temperature, the tensile strength and elongation at 150 ° C.
For o9, the tensile strength, yield strength and elongation at 300 ° C. were measured. Table 3 shows the results.

From Table 3, it can be seen that the aluminum-based composite materials of Examples Nos. 1 to 9 all have a tensile strength (σ) at room temperature (RT) exceeding 500 MPa, and even at 150 ° C.
It exceeds 50MPa. Therefore, each sample of this example indicates that the heat resistance is improved. As shown in Table 4, the comparative examples also show tensile strength and elongation at room temperature, tensile strength and elongation at 150 ° C, and tensile strength and yield strength at 300 ° C for Nos. The elongation was measured.

Comparative Examples No51, No52, No57, N
o58 is the same as the matrix composition of the present invention, and the tensile strength (σ) at room temperature exceeds 500 MPa, and even at 150 ° C. exceeds 450 MPa. The aluminum alloy of Comparative Example No. 51 has the same matrix composition as that of Example No. 1. Similarly, No. 52 has the same matrix composition as No. 2 and No. 57, and No. 8 and No. 58 has the same matrix composition. No remarkable adverse effect on the strength due to the addition of a material or boride is observed.

Comparative Examples No. 53 and No. 54 are those in which nitrides and borides are blended in a matrix consisting only of Al, Ni and Si, and have a tensile strength (σ) at room temperature of 500 PM.
at 150 ° C. below 450 a. In addition, when the nitride was added to the matrix containing no Zr and Mo of No. 55 of Comparative Example, the tensile strength (σ) at room temperature was 500 PMa or less, and the tensile strength (σ) at 150 ° C. was 450 PMa or less. is there. No. 56 of the comparative example has Ni, Fe, Si (only 0.6% ) in the matrix ,
Since it does not contain Zr and Mo , the tensile strength (σ) at ordinary temperature and 150 ° C. is as low as 400 PMa or less.

Further, in Example No. 8, since 1% of Ti was added, the yield point at 300 ° C. did not include Ti.
9 has been improved. Therefore, the intended strength can be obtained by using the Al matrix composition of the present invention. [Evaluation 2] A test piece T / P of φ10 mm × 15 mm was cut from an aluminum-based composite material and an aluminum alloy having the compositions shown in Tables 1 and 2 and each sintered body obtained in the same manner as in Evaluation 1. Then, 5 to 8 tubes were prepared. Then, as shown in FIG. 1, each test piece T / P was sandwiched between the dies, and at 450 ° C., the forging speed was changed at a forging speed of 70 mm / sec, and the forging to obtain the limit upsetting ratio (%) was performed. The test was performed. The results are shown in Tables 3 and 4.

The limit upsetting rate (%) is ε _hc = (h ₀
−h _c ) × 100 / h ₀ . Example No1 ~
No. 9 has a critical upsetting ratio (450 ° C.) of 6 which indicates forgeability.
0% or more and excellent forgeability. On the other hand, in the comparative example,
51, No. 52 and No. 56 are marginal upsetting rates (450
° C) is 60% or more and has excellent forgeability. However, No. 53 and No. 54 containing nitride and boride have a critical upsetting ratio of 50% because the matrix Ni is 15% and the Si is 20%.
% Or less, and the others could not be measured. Comparative Example No.
In the case of No. 55, Ni of the matrix is 10%, Si is 25%, and the elongation at 300 ° C. is 0.2%. Therefore,
The forgeability is not improved only by blending nitride and boride into the Al matrix. This indicates that the setting of the matrix composition is necessary.

The excellent forgeability of the composite material of the present invention is due to the addition amounts of Ni, Si, and Fe (particularly, Si) of 15%, 15%, and 8% or less, respectively. [Evaluation 3] Next, wear tests were performed on the aluminum-based composite materials of Examples 1 to 9 and the aluminum alloys of Comparative Examples 51 to 58. The amount of abrasion was measured using a LFW tester under the test conditions in which a ring-shaped mating member immersed in oil was used as SUJ2, and a test piece was pressed against the SUJ2 under a load of 150 N, a time of 15 minutes and a sliding speed of 18 m / min.

The results are shown in Tables 3 and 4. From Table 3, the specific wear (LFW test) of the samples of Examples Nos. 1 to 9 was 1.3 × 10 ⁻⁷ mm ³ / kg · mm or less, and was balanced with high-temperature strength, forgeability, and wear resistance. It is an aluminum-based composite material. Comparative Example N containing no nitride or boride
o51, No52 and No56 show that the critical upsetting ratio (450 ° C.) indicating forgeability from Table 4 may be 75% or more,
The specific wear amount is as large as 4.0 × 10 ⁻⁷ and the wear resistance is low. Comparative Examples No. 53 and No. 54 contain nitrides and borides, and thus have a specific wear amount of 2 × 10 ⁻⁹ and 3 × 10 ⁻⁹ , but a good wear resistance, but a critical upsetting ratio indicating good or poor forging property of 40.5. %, 45.0%
And low.

Therefore, in order to obtain an aluminum-based composite material having a good balance of strength, heat resistance, forgeability and abrasion resistance, it is necessary to select a matrix composition and specify the amounts of nitrides and borides. is there. Therefore, according to the above evaluation, the aluminum-based composite material produced by sintering the powders of the aluminum-based composite materials of Examples Nos. 1 to 9 was lightweight, and exhibited wear resistance, forgeability, tensile strength at room temperature and high temperature. Excellent strength.

[0037]

As described in detail above, the aluminum-based composite material of the present invention uses an aluminum alloy containing predetermined amounts of Ni, Si, Fe, Cu and Mg, Zr and Mo as a matrix. It is lightweight, has excellent wear resistance because nitride and boride particles are dispersed in the matrix, and is almost similar to an aluminum alloy composed of a matrix in which nitride and boride particles are not dispersed. Has strength.

Therefore, the aluminum-based composite material of the present invention can contribute to weight reduction of valve spring retainers, intake valves, pistons and the like, which are engine parts of automobiles and the like. Furthermore, since this aluminum-based composite material can exhibit stable wear resistance, toughness, forgeability, rigidity, thermal expansion characteristics, room temperature strength and high temperature strength, it surely responds to the demand for high output in recent years, In addition, since the weight can be reduced, it is possible to provide an engine part with low fuel consumption.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a method for measuring a critical upsetting ratio in Evaluation 2.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C22C 1/10 C22C 1/10 J (72) Inventor Hirofumi Michioka 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Jun Kusui 3-6-8 Kutaro-cho, Chuo-ku, Osaka-shi Toyo Aluminum Co., Ltd. (72) Inventor Shoei Tanaka 3-6-8 Kutaro-cho, Chuo-ku, Osaka-shi Toyo Aluminum Co., Ltd. (56 References JP-A-6-158200 (JP, A) JP-A-3-294446 (JP, A) JP-A-60-204857 (JP, A) JP-A-56-116851 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 21/00-21/18 C22C 32/00 B22F 1/00 C22C 1/04-1/10

Claims (2)

(57) [Claims] 1. When the matrix is 100% by weight
By weight%, Ni: 2 to 15%, Si: 0.2 to 15%,
Fe: 0.6-8.0% and Cu: 0.6-5.0%
And Mg: 0.5-3%(However, Cu + Mg ≦ 6%)
And Zr: 0.3-3% and Mo: 0.3-3%(T
(Zr + Mo ≦ 4%)And the rest are unavoidable impurities
A heat-resistant aluminum alloy consisting of
100% by weight of the entire composite material containing the matrix
One or more of nitride and boride particles
Are dispersed in the matrix in a total amount of 0.5 to 10% by weight,
High durability, characterized by being manufactured by powder metallurgy
Heat and wear resistant aluminum matrix composite material. 2. The high heat and wear resistant aluminum-based composite material according to claim 1, wherein the matrix contains 100% by weight of Ti and 0.5 to 4.0% by weight of Ti.