JPH10298684A - Aluminum matrix alloy-hard particle composite material excellent in strength, wear resistance and heat resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an Al matrix alloy-hard particle composite material excellent in heat resistance, room temp. strength, high temp. strength and hardness, high in specific strength and having wear resistance by dispersing hard fine particles into an Al matrix essentially consisting of α-Al phases and having strength and elongation. SOLUTION: The molten metal of an Al alloy having a compsn. shown by the general formula of Albal Ma Xb where M denotes one or two kinds of Fe and Co, X denotes one or >= two kinds among Ti, rare earth metals including Y and misch metals, and as for (a) and (b), by atomic, 3<=a<=8 and 0<=b<=5 are satisfied} is solidified by a melt quenching method such as a single roll method or the like to produce an α-Al solid solution. The matrix essentially consisting of the powder of the α-Al solid solution is mixed with the hard particles of carbide, nitride, oxide, boride or the like of <=10 μm average particle size by 3 to 20 vol.% by a ball mill or the like, and they are dispersed and incorporated therein. This powdery mixture material is solidified by a hot pressing or the like to obtain the Al matrix alloy-hard particle composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aluminum-based alloy-hard particle composite material having excellent mechanical properties such as strength, abrasion resistance and heat resistance.

[0002]

2. Description of the Related Art Conventionally, an aluminum-based alloy having high strength and heat resistance has been manufactured by rapid solidification means such as a liquid rapid cooling method. Particularly, the aluminum-based alloy obtained by the rapid solidification means disclosed in Japanese Patent Application Laid-Open No. 1-275732 is an amorphous alloy or a composite structure alloy of amorphous and microcrystalline.

Next, a eutectic or hypereutectic Al-Si alloy conventionally known as a wear-resistant aluminum-based alloy exhibits excellent wear resistance because hard Si is dispersed in a matrix. . However, since the size of the primary crystal Si of the cast Al-Si alloy is as coarse as several tens of μm or more, it is difficult to process the cast Al-Si alloy. Therefore, it is necessary to finish the cast product as close as possible to the final product. However, Al-Si alloys have poor production properties, and thus have many manufacturing problems.

[0005] Further, as a powder metallurgy method, there is known an alloy in which a high Si-Al alloy of about 35% Si is increased in cooling rate by an atomizing method and primary Si is finely dispersed. However, because of its low hardness and its brittleness, its suitability as a practical alloy was less satisfactory than that of a cast material.

[0006] In order to solve the above-mentioned problems, Si-containing aluminum-based alloys having high strength and wear resistance have been manufactured by rapid solidification means such as a liquid quenching method. In particular, JP-A-5
The aluminum-based alloy disclosed in JP-A-222478 has a composite structure composed of a microcrystalline aluminum base phase, a stable or metastable intermetallic compound phase, and Si particles, and has strength and wear resistance. It is high and has good workability as a high-strength material. However, the size of Si particles and intermetallic compound particles that are crystallized through the process of rapid solidification for high strength is small, leaving room for improvement in terms of wear resistance.

[0007] Japanese Patent Publication No. Sho 6
The alloy described in Japanese Patent Publication No.
Heat resistance and abrasion resistance are improved by dispersing Si, SiC, Si ₃ N ₄ etc. in aluminum-based alloys, but the strength is 30 kg / mm ² or less. There is. Further, the elongation is 1% or less at room temperature, and it is sometimes difficult to process.

[0008]

Accordingly, the present invention provides an excellent heat resistance and a room temperature strength by dispersing hard particles of 10 μm or less in an Al matrix mainly composed of an α-Al phase having strength and elongation. It is another object of the present invention to provide an aluminum-based alloy-hard particle composite material having excellent high-temperature strength and hardness, high specific strength, and abrasion resistance.

[0009]

Means for Solving the Problems] To solve the above problems the present invention have the general formula: Al _bal M _a X _b (where, M: Fe,
One or more selected from Co, X: Ti, Y
A rare earth element containing (yttrium) or one or more elements selected from misch metal (Mm), wherein a and b are atomic percentages and are represented by 3 ≦ a ≦ 8, 0 ≦ b ≦ 5) Excellent in strength, abrasion resistance and heat resistance, characterized in that 3 to 20% by volume of hard particles having an average particle size of 10 μm or less are dispersed in a matrix mainly composed of an α-Al phase. An aluminum-based alloy-hard particle composite is provided.

The matrix of the aluminum-based alloy-hard particle composite material of the present invention comprises an α-Al (supersaturated solid solution) phase. Here, when the amount of the M element is 3 atomic% or more, the amount of solid solution in the equilibrium state is exceeded, so that α-Al containing a solute becomes a supersaturated solid solution. In addition, the matrix is composed of one or more kinds of intermetallic compounds generated by α-Al, aluminum and other elements (M, X), or one or more intermetallic compounds generated by other elements (M, X). It may be composed of a composite phase contained in Al supersaturated solid solution crystal grains as two or more secondary phases. Here, the intermetallic compound is effective for strengthening the matrix and controlling the crystal grains.

The composite material of the present invention is prepared by solidifying a molten Al alloy having the composition of the above general formula by a liquid quenching method such as a single roll method, a twin roll method, various atomizing methods, and a spraying method. The oxide, carbide, nitride,
It can be obtained by mixing hard particles such as boride with a ball mill or the like and uniformly dispersing the hard fine particles. In the case of these methods, the base alloy can be formed into a supersaturated solid solution or a composite structure of a supersaturated solid solution and an intermetallic compound at a cooling rate of about 10 ² to 10 ⁴ K / sec, although it slightly varies depending on the alloy composition.

The aluminum-based alloy powder having an average particle diameter of preferably 20 to 30 μm is mixed with hard particles having an average particle diameter of preferably 1 to 10 μm by a ball mill or the like. It is effective to perform the ball milling in a dry manner. In the case of the wet method, the powder may be oxidized, and then, when the powder is solidified and formed, the hard particles have poor bonding properties and the hard particles may fall off, which may not contribute to the wear resistance. Mixed powder hot extrusion, hot pressing, HIP
It is made into a composite material by solidifying it. The porosity of the composite material is preferably as small as possible, and particularly preferably 2% by volume or less. The aluminum-based alloy is, for example, 25
Heat treatment at 0 to 450 ° C. for 30 minutes or more can precipitate the intermetallic compound. Here, the heat treatment temperature is 45
When the temperature exceeds 0 ° C., almost all of the X and M components are precipitated, so that the supersaturated solid solution cannot be maintained. On the other hand, when the heat treatment temperature is less than 250 ° C. and the heat treatment time is less than 1 hour, there is no remarkable effect. The heat treatment may be performed before or after solidification.

Hereinafter, the reasons for limitation of the present invention will be described in detail. 3～8At% content a of M (Fe, Co) in atomic% in the general formula _{Al bal M a X b, X} (T
(i, the rare earth element) b is limited to the range of 0 to 5 at%, respectively, as long as it is within the range, the room temperature strength is higher than the conventional (commercially available) high-strength aluminum alloy, and the high-temperature strength at 300 ° C. or higher is higher. This is because it has a high Young's modulus and at the same time has ductility enough to withstand practical processing. The remainder of a and b, that is, 100-ab is Al.

The M element is one or two elements selected from Fe and Co, and improves the thermal stability. The X element is one or two selected from rare earth elements containing Ti and Y (yttrium) or misch metal (Mm).
More than one kind of element. Since these elements are elements having a low diffusivity with respect to Al, the concentration segregation of the X element in the aluminum matrix during rapid solidification has the effect of strengthening the matrix in a high X concentration region, whereas the low X concentration A in the segregation zone
Excellent growth is maintained at base l. Therefore, X
The low diffusivity of the elements is a beneficial property. Further, the elements contained in the X component form various intermetallic compounds with the main element Al or other elements, and contribute to improvement of the strength of the alloy and heat resistance. In addition, during cooling of the molten alloy, many of the elements of the X component crystallize out of the molten aluminum as fine crystals to form nuclei, refine the Al crystals, improve the mechanical properties, and improve the ductility of the alloy. Let it.

As described above, in the present invention, the base structure of the alloy comprises a single phase of α-Al (supersaturated solid solution) or the above-mentioned composite phase. The average particle size of various intermetallic compounds that may constitute the base structure is preferably from 10 to 1000 nm. When the average particle size is less than 10 nm, the strength of the alloy does not increase, and the number of intermetallic compounds per unit area becomes too large, which may cause the alloy to become brittle. On the other hand, when the average particle size of the intermetallic compound exceeds 1000 nm, the particles become too large and do not function as a reinforcing element, so that the strength of the alloy cannot be maintained. Further, in order to balance strength, hardness and ductility at a high level, the average interparticle distance of the intermetallic compound is preferably from 10 to 500 nm. When the average interparticle distance of the intermetallic compound particles to be strengthened by the dispersion strengthening mechanism is in the range of 10 nm to 500 nm, the strength and ductility are particularly good, and the properties as a superplastic material are imparted at a high temperature.

Next, the hard particles which are dispersed phases in the matrix will be described. Hard particles are generally H
Particles of a compound having a hardness of v1000 to 2000 and having a hardness substantially higher than that of the base (including a complex compound in which two or more compounds are compounded). The hardness difference is at least three times or more, preferably five times or more. The hard particles are preferably selected from carbides, nitrides, oxides and borides. Carbides TiC, SiC, WC, etc. NbC, nitrides AlN, TiN, etc. _{Si 3 N 4, c-BN} , oxide such as _{Al 2 O 3, SiO 2,} TiO 2, borides T
It is selected from iB, FeB and the like. The average particle size of the dispersed hard particles is 10 μm or less. If it exceeds 10 μm, the strength and machinability decrease. The reason why the dispersion amount of the hard particles (the ratio to the whole composite material) is limited to 3 to 20% by volume is that the wear resistance is insufficient at 3% by volume or less, and the strength and toughness decrease at 20% by volume or more. is there.

[0017]

As described above, wear resistance can be added by dispersing hard particles in a base alloy having high temperature, room temperature strength, ductility, fatigue strength, Young's modulus and the like. On the other hand, the composite Al alloy mixed with the conventional hard particles has improved properties such as strength and sharply reduced elongation, but the alloy of the present invention has high toughness due to the excellent properties of the matrix.

Representative properties of the composite material of the present invention are as follows. Tensile strength (room temperature): 750 to 900 MPa, equivalent to steel material Specific gravity: 3.0 to 3.3, about 20% heavier than general aluminum alloy wrought material Specific strength: 2.3 × 10 ⁴ m Ultra super duralumin (A70) which is a representative of 3.0 × 10 ⁴ m high strength aluminum alloy
1.5) Ductility: 2 to 5% as compared with 75) High temperature strength: 1.5 to 2 times of A7075 in terms of hardness at 400K Abrasion resistance: described in [0026] The composite material of the present invention is used at high temperature It is suitable as a lightweight sliding material.

The aluminum alloy of the present invention can control the alloy structure, the particle size of each phase, the dispersion state, and the like by selecting appropriate production conditions. That is, the structure of the alloy can be selected from either a single phase or a multi-phase by controlling the addition amounts of the M and X components, controlling the cooling rate, and heat treatment. The particle size of each phase can be controlled by the powder particle size, and the dispersibility can be controlled by the ball mill mixing conditions. By this control, strength, hardness, ductility, heat resistance and the like can be adjusted. Hereinafter, the present invention will be specifically described based on examples.

[0020]

【Example】

Example 1 A master alloy having a composition (atomic ratio) represented by Al ₉₃ Fe _3.5 Ti _3.5 was melted in a high-frequency melting furnace, and a powder having an average particle diameter of 23 μm was manufactured by a high-pressure gas atomization method (Ar gas). The gas pressure at that time was 80 kg / cm ² . As a result of X-ray diffraction, the produced powder had a structure composed of an α-Al phase. 5% by volume of SiC powder having an average particle size of 3 μm
After mixing and mixing for 3 hours in a ball mill,
A mixed powder of Al-based alloy-SiC in which C was uniformly dispersed was obtained.

Example 2 The powder prepared in Example 1 was packed in a copper
After vacuum deaeration (1 × 10 ⁻⁵ torr) at ° C., a round bar having a diameter of 12 mm was obtained by warm extrusion at 360 ° C. at an extrusion ratio of 10. This extruded rod is placed in an Al matrix composed of an α-Al phase,
It had a structure in which SiC particles were uniformly and finely dispersed. FIG. 1 shows a structure photograph of the composite material observed with an optical microscope. The tensile strength and elongation at room temperature of this alloy were 776 MPa and 2.8%, respectively.

Example 3 Inventive alloys 1 to 19 having the compositions shown in Table 1 were produced as powders in the same manner as in Example 1, and then mixed with the dispersed particles shown in Table 1 by a ball mill for 3 hours. The mixed powder was extruded in the same manner as in Example 2, and the hardness and tensile strength of the obtained bulk material were examined. The results are shown in FIG. 6 (Table 1).

Comparative Example 1 FIG. 6 (Table 1) shows the base alloy composition and the type, amount and diameter of the dispersed particles. 20 to 24 were molded in the same manner as in Example 3. From FIG. 6 (Table 1), the alloy No. No. 20 has no hard particles added. No. 21 has low strength and hardness due to a small amount of hard particles added. No. Nos. 22 and 24 were no. 23 Hardness is high but strength is low due to large hard particle diameter.

The composition of FIG. 6 (Table 1) is as follows, and comparative materials are indicated by *. _{1 Al 93 Fe 3.5 Ti 3.5 2} Al 93 Fe 3.5 Ti 3.5 3 Al 93 Fe 3.5 Ti 3.5 4 Al 93 Fe 3.5 Ti 3.5 5 Al 92.5 Fe 3.5 Ti 3.5 Ce 0.5 6 Al 92.5 Fe 3.5 Ti 3.5 Ce 0.5 7 Al 92.5 Fe _{4 Co 3 Nd 0.5 8 Al 92.5} Fe 3.5 Co 3.5 Nd 0.5 9 Al 92.5 Fe 3 Co 4 Nd 0.5 10 Al 92.5 Fe 4 Co 3 Ce 0.5 11 Al 92 Fe 4 Co 3 Nd 0.5 Ti 0.5 12 Al 92.5 Fe 3.5 Co 4 _{Ce 0.5 Ti 0.5 13 Al 92.5 Fe} 4 Co 3 Ce 0.5 Ti 0.2 14 Al 93 Fe 3.5 Ti 3.5 15 Al 93 Fe 3.5 Ti 3.5 16 Al 93 Fe 3.5 Ti 3.5 17 Al 93 Fe 3.5 Ti 3.5 18 Al 93 Fe 4 Co 3 _{19 Al 93 Fe 3 Co 4 20} * Al 93 Fe 3.5 Ti 3.5 21 * Al 93 Fe 3.5 Ti 3.5 22 * Al 93 Fe 3.5 Ti 3.5 23 * Al 93 Fe 3.5 Ti 3.5 24 * Al _92.5 Fe _3.5 Ti _3.5 Ce _0.5

Comparative Example 2 The hardness and test results of an A390 sintered material (tempered T ₆ ) known as a wear-resistant alloy were measured, and the results are shown in FIG. 6 (Table 1) (No. 25).

Example 4 and Comparative Example 2 The alloy No. 3 shown in Example 3 was used. 1, 2, 5, 8, and 18 and the alloy No. 1 shown in Comparative Example 1. 20, 21, 2
2 was processed into a test piece 1 as shown in FIG.
As shown in the figure, contact with the counterpart material 2 (eutectic cast iron) and load 10k
The wear test was performed under the conditions of gf / mm, speed 1 m / s, lubricating oil = Nisseki Refoil (NS-4GS), and test time 20 minutes. FIG. 4 shows the results. For the evaluation of the amount of wear, the test material was measured for the width of the wear mark, and the mating material was measured for the Vickers indentation (load: 1 kg) on the sliding surface before the abrasion test, and the indentation diameter was measured again after the test. The difference was taken as the amount of wear.

A390 alloy (No. 25) and Comparative alloy No. In the case of No. 22, the mating material was also used as the comparative alloy 20, 20
In the case of 1, the test material itself wears much, but in the case of the present invention, the wear amount of both itself and the mating material is small, and it is understood that the material of the present invention has good compatibility with the mating material.

Example 5 Of the extruded materials shown in Example 3, Alloy No. 2 and the alloy No. 2 of the present invention. 7 shows the results of the high temperature hardness test.
As a comparative material, the high-temperature hardness of a practical high-strength Al alloy 7075-T6 treated material is also shown. It can be seen that the material of the example of the present invention has a higher hardness than the 7075-T6 material and has improved heat resistance.

[0029]

As described above, the alloy of the present invention is excellent in strength at room temperature and excellent in heat resistance, and has a high strength and a low specific gravity due to a small amount of rare earth element added. An aluminum-based alloy having wear resistance can be provided by using a material as a matrix and uniformly dispersing hard particles therein. In addition, by having excellent heat resistance, excellent characteristics produced by the rapid solidification method and characteristics produced by heat treatment or thermal processing can be maintained even under the influence of heat during processing.

[Brief description of the drawings]

FIG. 1 is a photograph showing a metal structure by an optical microscope in Example 2.

FIG. 2 is a view of a wear test piece.

FIG. 3 is an explanatory diagram of a wear test method.

FIG. 4 is a graph showing the results of a wear test in Example 4.

FIG. 5 is a graph showing the results of a high-temperature hardness test in Example 5.

FIG. 6 is a table (Table 1) showing compositions and test results of Example 3 and Comparative Examples 1 and 2.

[Explanation of symbols]

 1 Test piece (test material) 2 Counterpart material

Continuation of the front page (51) Int.Cl. ⁶ identification symbol FI // C22F 1/00 603 C22F 1/00 603 621 621 627 627 628 628 628 630 630 630D 650 650A 687 687 (72) Inventor Masahiro Koguchi Chuo-ku, Tokyo 1-9-9 Yaesu Imperial Piston Ring Co., Ltd. (72) Inventor Akihisa Inoue 35-35 Kawachimoto Hasekura, Aoba-ku, Aoba-ku, Sendai City, Miyagi Prefecture 11-806 Kawauchi House (72) Inventor Noto Kawamura Aoba, Sendai-shi, Miyagi Prefecture 2-1-1 Katahira-ku, Tohoku University Institute for Materials Research

Claims (5)

[Claims] 1. A general formula Al _bal M _a X _b (where, M: F
one or two elements selected from e and Co, X: T
one or more elements selected from the group consisting of rare earth elements containing i and Y (yttrium) or misch metals (Mm), and a and b are atomic percentages of 3 ≦ a ≦ 8, 0 ≦ b ≦
5) Hard particles having an average particle size of 10 μm or less are contained in a matrix mainly composed of α-Al solid solution having a composition represented by 5).
An aluminum-based alloy-hard particle composite material having excellent strength, abrasion resistance and heat resistance characterized by being dispersed in 0% by volume. 2. The aluminum-based alloy according to claim 1, wherein said hard particles are one or more selected from carbides, nitrides, oxides and borides. Hard particle composite material. 3. The method according to claim 1, wherein the matrix comprises the α-Al phase solid solution,
The aluminum-based alloy having excellent strength, wear resistance and heat resistance according to claim 1 or 2, wherein the element M or M and X comprises an intermetallic compound formed by themselves or by combining with aluminum. Particle composite material. Wherein the general formula Al _bal M _a X _b strength according to any one of powder of rapidly solidified material from claim 1 which solidified molded with the hard particles up to 3 having a composition of, wear resistance and heat resistance Aluminum based alloy-hard particle composite material with excellent properties. 5. The strength according to claim 4, wherein the rapidly solidified material is heat-treated at 250 to 450 ° C. before or after solidification molding.
Aluminum-based alloy-hard particle composite material with excellent wear resistance and heat resistance.