JPH0892680A - High strength aluminum-based alloy - Google Patents

Abstract

PURPOSE: To enhance the elongation, heat resistance, strength and specific strength of a quasi-crystalline Al alloy. CONSTITUTION: This Al-based alloy has a compsn. represented by the general formula Al100-a-b-cQaMbXc [where Q is one or more kinds of elements selected from among Cr, Mn, Fe, V, Mo and W, M is Co and/or Ni, X is one or more kinds of elements selected from among Ti, Zr, Hf, Nb, rare earth elements including Y and misch metal, (a) is 1-7at.%, (b) is 0.5-5at.% and (c) is >0 to 5at.%] and has disordered atomic arrangement in a short range of about <=1nm and a texture contg. quasi crystals having a regular eicosahedral structure in a long range of about >=2nm. This alloy is excellent in hardness and strength at high temp.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength aluminum alloy, and more specifically to an aluminum-based alloy excellent in mechanical properties such as high hardness / high strength and elongation and high in specific strength.

[0002]

2. Description of the Related Art Conventionally, aluminum-based alloys having high strength and high heat resistance have been manufactured by a rapid solidification method such as a liquid rapid cooling method. In particular, the aluminum-based alloy obtained by the rapid solidification means disclosed in Japanese Patent Laid-Open No. 1-275732 has an amorphous or microcrystalline structure, and the disclosed microcrystalline material is an aluminum matrix. And a complex composed of a microcrystalline aluminum matrix phase and a stable or metastable intermetallic compound phase.

The aluminum-based alloy disclosed in JP-A-1-275732 has high strength, high heat resistance,
It is an excellent alloy that exhibits high corrosion resistance, and is excellent in workability as a high-strength material, but in the high temperature range of 300 ° C or higher, the excellent properties as a rapidly solidified material deteriorate, so heat resistance In particular, there is room for improvement in terms of heat resistance.
Further, since the alloy of the above publication adds an element having a relatively high specific gravity, the specific strength does not become relatively high, and there is room for improvement in terms of high specific strength. Further, the alloy of the above publication has a low ductility because of a high volume ratio of the intermetallic compound, and there is room for improvement particularly in the point of elongation.

By the way, the present inventors have conducted research and published papers on an Al-Mn-Ce type aluminum alloy having a quasi-crystalline structure, and a part of the research has been given as a seminar text "Nanoscale Structure Control Material" (Company). The Japan Institute of Metals, published January 25, 1993, pages 63-66, summarizes and explains. As explained in this text, Al93Mn4Ce3, Al92Mn6Ce2 with quasicrystalline structure
Has a low melt mass of 7 to 8 at%, has a high tensile strength of 1320 MPa, and its specific strength is about 20% higher than the conventional highest strength amorphous aluminum alloy. Furthermore, quasicrystal is 5
It was observed that the electron diffraction pattern in the 7 nm region had a crystal grain size of 0 nm and showed ring-shaped diffuse spots.

[0005]

The quasicrystalline aluminum alloys researched and announced by the present inventors have high strength and specific strength, but higher elongation and heat resistance are desired for practical use. Be done. Further, it is desired to further increase the strength and specific strength by further reducing the solute element content.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of further studying the structure of the quasicrystal, a matrix made of aluminum has a disordered atomic arrangement at least in the short-range region of about 1 nm or less in the structure and a regular icosahedron structure in the long-range region of about 2 nm or more. It was discovered that an aluminum-based alloy having excellent heat resistance, strength at room temperature and strength and hardness at high temperature, high specific strength, and viscosity can be provided by forming a finely dispersed structure of the quasicrystals. That is, the quasicrystal of the present invention moves the region in which the regular icosahedron structure is formed to the shorter range side than the conventionally announced quasicrystal, and the disordered atomic arrangement is 1
By setting the short range to not more than nm, good viscosity is exhibited.

The aluminum alloy composition for forming the above quasicrystals and improving the mechanical properties is represented by the general formula Al100-abc Qa Mb Xc (where Q: Cr, Mn,
Rare earth containing one or more elements selected from Fe, V, Mo and W, one or two elements selected from M: Co and Ni, and X: Ti, Zr, Hf, Nb and Y (yttrium) One or more elements selected from elements or misch metal (Mm), a, b,
c is atomic% and 1 ≦ a ≦ 7, 0.5 ≦ b ≦ 5, 0 <c ≦
It is the composition shown in 5).

The quasicrystal has a disordered atomic arrangement in a short range of about 1 nm or less and a regular icosahedral structure in a long range of about 2 nm or more.
h is a supersaturated quasi-periodic structural phase, and the solute element is Q,
M and X. The quasi-periodic structure means that the above-mentioned disordered structure and ordered structure are observed periodically. The quasicrystal characterized by the present invention has the above-mentioned single-range ordered structure and A
High viscosity is expressed due to the l-rich composition. The solute element content of the quasicrystal is considered to be higher than that of the amorphous alloy phase described below, but the fact that the viscosity is excellent nevertheless is a characteristic peculiar to the quasicrystal structure. In the alloy of the present invention, it is possible to crystallize a quasi-crystal in the primary crystal to increase the amount of molten mass taken therein, and then to adjust the cooling rate so that another phase having a small amount of molten mass is formed. It is preferable for improving strength.

The structure of the aluminum alloy according to the present invention is
Preferably, it may substantially consist of a quasicrystal having a volume ratio of 20 to 80% and one or more of an amorphous alloy, an aluminum crystal and a supersaturated solid solution of aluminum. Although these amorphous alloys, aluminum crystals, and supersaturated solid solutions of aluminum are also Al-rich structures, the strength is lower than that of quasicrystals, and the tendency of viscosity is almost aluminum alloy>quasicrystals> supersaturated aluminum solid solution> or ≒ It is an amorphous alloy.

Since the elements Q and X accelerate the amorphization, if the amount of these elements is large, the tendency of forming an amorphous alloy increases. When the amount of Q and X elements is small, the tendency of forming aluminum crystals or aluminum supersaturated solid solution is large, and when the amount of total solute elements is large, the latter is formed.

On the other hand, since the intermetallic compound has a very low viscosity, it is not preferable to occupy a major proportion of phases other than the quasicrystal, such as an amorphous alloy, an aluminum crystal and a supersaturated solid solution of aluminum. It may have been done.
That is, in the present invention, aluminum and Q, M,
Even if a first intermetallic compound formed with at least one element contained in X and / or a second intermetallic compound contained in Q, M, X and formed with two or more elements is contained Good. These intermetallic compounds contained in appropriate amounts are finely dispersed in the structure and are effective for strengthening the matrix and controlling the crystal grains. The amount is preferably in the range not exceeding the above-mentioned amorphous alloy, aluminum crystal and supersaturated solid solution of aluminum, and particularly preferably in the range of 3 to 10% by volume.

The aluminum-based alloy of the present invention is prepared by melt-melting the alloy having the above composition by a single roll method, a twin roll method, a rotating submerged spinning method, various atomizing methods, a liquid quenching method such as a spray method, a sputtering method, a mechanical alloying method. It can be obtained directly by the ing method, the mechanical gliding method, or the like. In the case of these methods, the production can be carried out at a cooling rate of about 10 @ 2 to 10 @ 4 K / sec, although it depends on the alloy composition. The aluminum-based alloy of the present invention can also be obtained by heat-treating the rapidly solidified material obtained by the above manufacturing method. Alternatively, the aluminum-based alloy of the present invention can be obtained by assembling a rapidly solidified material and subjecting it to heat processing such as compaction and extrusion to precipitate quasicrystals from the supersaturated solid solution. The temperature at this time is preferably 300 to 600 ° C.

The reasons for limiting the composition of the aluminum alloy of the present invention will be described in detail below. The general formula Al100-a-
in bc Qa Mb Xc, a is 1 to 7 at% in atomic%,
b is 0.5 to 5 at%, c is 0 (0 is not included) to 5 a
Each of the ranges of t% is limited to within the range, the strength is higher than that of the conventional amorphous high-strength aluminum alloy even at room temperature and high temperature of 300 ° C. or more, and moreover, it can withstand practical working. This is because it has only tenacity. If the amount of Q, M, or X is less than the lower limit, the strength will be extremely low, while if it is more than the upper limit, the structure will tend to become amorphous and the viscosity will be significantly reduced.

In order to obtain a high specific strength material by reducing the amount of solute element having high specific gravity, 3 ≦ (a + b + c) ≦ 8 is preferable.
Range. After balancing Q, M and X elements,
It is also possible to set the range of 3 ≦ (a + b + c) ≦ 7. A material having a tensile strength of about 1200 MPa or more and a high specific strength can be obtained by setting the total amount of the Q, M and X elements to 3 to 5.5 at%. However, in this case, b = 1 to 2
It is preferable to balance at% and c = 0.8 to 1.3% and the amounts of Q, M and X elements.

Q element is Cr, Mn, Fe, V, Mo, W
It is one or two or more kinds of elements selected from, and is an element indispensable for the formation of quasicrystals. Furthermore, by combining with the M element described later, it is possible to easily generate a quasicrystal with a low solution mass and to improve the thermal stability of the alloy structure.

The M element is one or two elements selected from Co and Ni. By combining these elements with the above Q element, it is possible to facilitate the formation of quasicrystals with a low melting mass and to combine with the Q element. It also improves thermal stability. In addition, the M element is an element having a small diffusivity with respect to Al which is the main element, has an effect of strengthening the Al matrix, and forms various intermetallic compounds with Al which is the main element or other elements to form an alloy. Contributes to improved strength and heat resistance.

The X element is Ti, Zr, Hf, Nb,
One or more elements selected from rare earth elements including Y (yttrium) or misch metal (Mm), and these elements are effective in expanding the quasicrystal formation region to a low solute concentration of the added transition metal. In addition, it has an effect of improving the refining effect by cooling the alloy liquid. Therefore, these elements have the effect of improving the mechanical properties by the refinement effect and also improving the viscosity by the formation of quasicrystals with a low solute concentration. Therefore, by using the composition represented by the above general formula, Young's modulus, high temperature / room temperature strength, viscosity, fatigue strength and the like can be further improved. It is desirable for a practical material that the tensile strength at room temperature is 500 MPa or more and the elongation is 5% or more. Further, according to the present invention, it is possible to obtain a very excellent mechanical property that the strength is equivalent to that of high strength steel and the elongation is 15% or more in a wide range of compositions.

In the above, the quasicrystal contained in the alloy structure is preferably 20 to 80% in volume ratio. 20%
If it is less than 8, the object of the present invention cannot be sufficiently achieved, and
If it exceeds 0%, embrittlement of the alloy is caused, and there is a possibility that the obtained material cannot be sufficiently processed. Further, the quasicrystal contained in the alloy structure is more preferably 50 to 80% by volume.

Further, in the present invention, it is preferable that the quasi-crystal, the amorphous phase, the aluminum crystal phase, and the supersaturated solid solution phase of aluminum which constitute the alloy structure are uniformly dispersed. Various intermetallic compounds can be produced by heating an alloy in the form of a quenching material or a solidifying material having a quasicrystalline phase structure and optionally the secondary phase structure described above, preferably at 450 to 600 ° C. The average particle size of these quasicrystals and intermetallic compounds, which is basically determined mainly by the cooling and heating conditions of the alloy liquid, is preferably 10 to 1000 nm. When the average particle size is less than 10 nm, it is difficult to contribute to the strength of the alloy, and when a large amount of particles less than 10 nm are present in the structure, there is a risk of causing embrittlement of the alloy, while the average particle size exceeds 1000 nm. If the particles are too large, the particles become too large, the function of the strengthening phase disappears, the strength cannot be maintained, and the function as a strengthening element decreases.

Further, it is preferable that the average interparticle distance between the closest quasicrystalline particles adjacent to each other through another phase is 10 to 500 nm, which is basically determined by the cooling rate and the amount of solute elements. When the average inter-particle distance is less than 10 nm, the obtained alloy has high strength and hardness but becomes insufficient in terms of viscosity, and when it exceeds 500 nm, the strength sharply decreases and a high strength alloy cannot be obtained. This is because the possibility arises.

In the aluminum-based alloy of the present invention,
By selecting manufacturing conditions such as amount of solute element, cooling rate of molten metal, heating temperature and time of laminated material, processing temperature, processing degree, degassing heating temperature of powder-filled billet, alloy structure, quasicrystal, etc. It is possible to control the particle size of the phase, the state of dispersion, etc. By this control, for example, strength, hardness, etc. that meet various purposes of use
Viscosity, heat resistance, etc. can be obtained. Further, as described above, by controlling the average particle size of the quasicrystal or various intermetallic compounds in the range of 10 to 1000 nm and controlling the average interparticle distance in the range of 10 to 500 nm, excellent superplastic working The property as a material can also be given. Hereinafter, the present invention will be described in more detail with reference to examples.

[0022]

EXAMPLES The present invention will be specifically described below based on examples. Example 1 A mother alloy having a composition (atomic ratio) represented by Al94.5Cr3Co1.5Ce1 was melted in an arc melting furnace, and a ribbon (thickness) was formed by a commonly used roll type liquid quenching device (melt spinning device). S: 20 μm, width 1.5 mm) was manufactured. At that time, the roll is made of copper having a diameter of 200 mm, the rotation speed is 4000 rpm, and the atmosphere is Ar of 10 −3 torr or less. As a result of performing TEM observation and electron beam diffraction on the produced ribbon after electrolytic polishing, it was found that the texture of the ribbon was a mixed phase alloy composed of a quasicrystalline phase and an aluminum phase.

In FIG. 1 showing electron diffraction results, the white part is the aluminum crystal phase, and the black part has a diameter of about 30.
The quasi-crystalline phase of nm is uniformly dispersed in the matrix.
The quasi-crystalline phase had a volume ratio of 68% and was found to be the main phase in the alloy structure.

A ribbon quasicrystal obtained by the above method and A
FIG. 2 shows the result of high-resolution electron microscope observation of the quasi-crystal part in the two-phase structure consisting of l. The region (A) having a clear periodic contrast with a diameter of 5 to 10 nm was the Al phase as seen in the electron diffraction pattern (b), but in most other regions, not only the periodic contrast but also the regular icosahedron was used. No contrast showing symmetry 5 times peculiar to the quasicrystal was recognized at all. In addition, only broad halos were observed in the electron diffraction pattern (c) obtained from a minute region of 1 nm in this region. However, when the region of the electron diffraction pattern obtained from the region in which the periodic contrast is not observed is expanded to 3 nm, 10-fold symmetry is recognized as shown in FIG. Therefore, the phase regarded as a quasicrystal is a kind of Al-rich supersaturated quasi-crystal which has a disordered atomic arrangement in a short range region of about 1 nm or less and has an icosahedral structure in a long range region of about 2 nm or more. It was found to be a periodic structure phase.

Example 2 A mother alloy having a composition (atomic ratio) represented by Al99-a-bCra Cob Ce1 was melted in an arc melting furnace, and a ribbon (thickness: 20 μm, Width 1.5m
m) was produced. The strength of each manufactured ribbon was measured at room temperature by an Instron type tensile tester.
Further, the adhesion of 180 ° was bent and the viscosity of the alloy was examined. Table 1 shows the results.

[0026]

[Table 1] Composition (at%) Tensile strength 180 ° Al Cr Co Ce (MPa) adhesion bending Inventive example 1 Remainder 2 1 1 530 Possible Inventive example 2 Remainder 2 1.5 1 970 Possible Inventive example 3 Remainder 2 2 1 1020 Possible Inventive example 4 Remainder 3 1 1 1120 Possible Present invention example 5 Remaining 3 1.5 1 1340 Possible Present invention example 6 Remaining 3 2 1 1290 Possible Present invention example 7 Remaining 3 2.5 1 1250 Possible Present invention example 8 Remaining 3 3 1 965 Possible Present invention example 9 Remaining 4 1 1 1250 Possible Present invention example 10 Remaining 4 1.5 1 1280 Possible Present invention example 11 Remaining 4 2 1 1180 Possible Present invention example 12 Remaining 4 2.5 1 1010 Possible Present invention example 13 Remaining 5 1 1 1140 Possible Comparison Example 1 Remaining 8 1 1 990 Not possible Comparative example 2 Remaining 0 1 1 190 Possible

From Table 1, it was found that the alloy of the present invention is an alloy having a relatively low mass but excellent strength and excellent viscosity. The structure of the alloy was almost the same as in Example 1 as a result of TEM observation and electron diffraction.

Example 3 In Examples 1 and 2, by increasing the cooling rate during the production of the ribbon, it was possible to allow the amorphous phase to be mixed in the structure of the alloy. Further, by heating the thin strips obtained in Examples 1 and 2 to 450 to 600 ° C., the intermetallic compound was precipitated and the tensile strength could be increased.

Example 4 An aluminum-based alloy powder having the composition shown in Table 2 of FIGS. 4 and 5 was prepared by gas atomization. After filling the produced aluminum-based alloy powder in a metal capsule, degassing was performed to produce an extrusion billet. This billet was extruded by an extruder at a temperature of 300 to 600 ° C. to be solidified. Extruded material (solidified material) obtained under the above manufacturing conditions
Mechanical properties of room temperature (hardness, strength at room temperature,
Elongation) and mechanical properties at high temperature (1 at 300 ° C
The strength after holding for a time) was examined, and the results are shown in FIGS. 4 and 5 (Table 2).

From the results of Table 2, the alloy of the present invention (solidified material)
Compared with the conventional high-strength amorphous aluminum alloy, although having a small molten mass, it has excellent hardness and strength at room temperature, and has a very high elongation compared to the conventional alloy, and high temperature ( It can be seen that it has excellent properties in the environment (300 ° C.). In addition, although heating is performed in preparing the solidified material, it is understood that the alloy is excellent in heat resistance because the change in properties due to heating is small and the difference in strength between room temperature and high temperature is small.
Further, a TEM observation test was cut out from the extruded material obtained under the above manufacturing conditions, and the structure of the alloy and the grain size of each phase were observed. According to the results of TEM observation and electron diffraction, the quasicrystal has a disordered atomic arrangement in a short range region of about 1 nm or less, and a positive 2 in a long range region of about 2 nm or more.
It was a kind of Al-rich supersaturated quasi-periodic structural phase having an octahedral structure. In addition, the quasicrystal in the structure has a volume ratio of 20.
It was -80%.

Further, the alloy structure is a mixed phase of aluminum or a supersaturated solid solution phase of aluminum and a quasi-crystalline phase, and various intermetallic compound phases were present in this alloy depending on the alloy species. Further, the average particle size of the quasi-crystal phase and the intermetallic compound phase was 10 to 1000 nm, and the average interparticle distance was 10 to 500 nm. In the composition in which the intermetallic compound was deposited, the intermetallic compound was uniformly and finely dispersed in the alloy structure.

[0032]

INDUSTRIAL APPLICABILITY As described above, the alloy of the present invention has excellent hardness and strength at room temperature and high temperature, and has improved elongation, which has been a problem of conventional high hardness / high strength materials (amorphous aluminum alloys). In addition to being excellent in heat resistance, the addition amount of solute elements, especially rare earth elements such as Y and Ce, is small, so that it is also useful as a high specific strength material having high strength and small specific gravity. Furthermore, the AlMnC that the present inventors have previously studied
Even when compared with the e-type quasicrystalline alloy, the alloy of the present invention is excellent in the above-mentioned characteristics. In particular, in the present invention, due to the peculiarity of the structure, a certain amount of the quasi-crystalline phase having high heat resistance and high hardness is present, so that it has excellent high strength and heat resistance.

Further, by controlling the total amount of solute elements as in claims 2 to 4, a preferable specific strength can be obtained.

Further, since it has excellent heat resistance, it has excellent characteristics produced by the rapid solidification method even if it is subjected to the thermal influence at the time of processing according to claim 8, and it is produced by heat treatment or heat processing according to claim 9. It is possible to maintain the specified characteristics.

[Brief description of drawings]

FIG. 1 is a photograph showing a metal structure obtained by TEM observation of an alloy in Example 1 and an electron beam diffraction result.

FIG. 2 is a photograph showing a metal structure obtained by high-resolution TEM observation and electron beam diffraction results in Example 1.

FIG. 3 is a photograph showing a metallographic structure obtained by high-resolution TEM observation and electron beam diffraction results in Example 1.

FIG. 4 is a chart showing alloy composition and characteristics in Example 4.

5 is a chart showing alloy composition and characteristics in Example 4. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 000006828 Wakeikei Co., Ltd. 1 Izumicho, Kanda, Chiyoda-ku, Tokyo (71) Applicant 000004075 Yamaha Corporation 10-1 Nakazawa-cho, Hamamatsu-shi, Shizuoka (72) Inventor Inoue Akihisa Kawauchi, Aoba-ku, Sendai City, Miyagi Prefecture Kawauchi House 11-806 (72) Inventor Hisami Kimura 44 Fujihirabashi, Arahama, Watari Town, Watari District, Miyagi Prefecture

Claims (10)

[Claims] 1. A general formula Al100-abc Qa Mb Xc (provided that Q: one or more elements selected from Cr, Mn, Fe, V, Mo and W, one or more elements selected from M: Co and Ni, or Two elements, X: Ti, Zr, Hf,
It is one or more elements selected from rare earth elements including Nb, Y (yttrium) or misch metal (Mm), and a, b, and c are atomic percentages of 1 ≦ a ≦ 7,0.
5 ≦ b ≦ 5, 0 <c ≦ 5) and has a disordered atomic arrangement in a short range region of about 1 nm or less, and a regular icosahedron structure in a long range region of about 2 nm or more. A high-strength aluminum-based alloy having a structure including a quasicrystal having the same. 2. The method according to claim 1, wherein 3 ≦ (a + b + c) ≦ 8.
The high-strength aluminum-based alloy described. 3. The method according to claim 1, wherein 3 ≦ (a + b + c) ≦ 7.
The high-strength aluminum-based alloy described. 4. The high-strength aluminum-based alloy according to claim 1, wherein 3 ≦ (a + b + c) ≦ 5.5. 5. A structure substantially consisting of a quasicrystal having a volume ratio of 20 to 80% and one or more of an amorphous alloy, an aluminum crystal and a supersaturated solid solution of aluminum. The high-strength aluminum-based alloy according to any one of 1 to 6 above. 6. The structure further comprises aluminum and said Q,
A first intermetallic compound formed with at least one element contained in M, X and / or a second intermetallic compound formed with two or more elements contained in Q, M, X The high-strength aluminum-based alloy according to claim 1. 7. The high-strength aluminum-based alloy according to any one of claims 1 to 6, which is a rapidly solidified material. 8. The high-strength aluminum-based alloy according to claim 1, which is obtained by solidifying and molding a rapidly solidified powder. 9. A high-strength aluminum-based alloy obtained by heat-treating the rapidly solidified material according to claim 7 or the solidified molded material according to claim 8. 10. The high-strength aluminum-based alloy according to any one of claims 1 to 9, which has a tensile strength at room temperature of 500 MPa or more and an elongation of 5% or more.