JPH07268401A - High strength aluminum alloy (powder) and its production - Google Patents

Abstract

PURPOSE:To produce high strength aluminum alloy powder improved in strength and uniformity by subjecting aluminum material powder to mechanism alloying, oxidizing a part of the mechanical alloying powder and dispersing the produced oxides reinforcing particles. CONSTITUTION:A stage where pure aluminum powder, aluminum alloy powder or the mixture of the powder with at least one kind of auxiliary reinforcing particle powder selected among the group of ceramic powder (excluding oxides), intermetallic compounds and precursory composite body powder is subjected to mechanical alloying in an atmosphere of an inert gas and the powder is discharged into the air, is repeated for plural times. Thus, the oxidized film formed on the surface of the powder at the time of the discharge is pulverized, and simultaneously, is made composite into the aluminum matrix. Moreover, the oxides are mainly constituted of Al2O3 of about <=1mum, and the total content is regulated to about <=10wt.%. Thus, the lightweight aluminum alloy having high strength and excellent in heat resistance and wear resistance can be produced.

Description

Detailed Description of the Invention

[0001]

[Industrial application] High strength aluminum alloy (powder)
And its manufacturing method.

[0002]

2. Description of the Related Art The present inventor has conducted extensive research and development on an intermetallic compound dispersion strengthened aluminum alloy (powder) and a method for producing the same, and as a result of the development, Japanese Patent Application No. 5-2253 has already been published.
The invention of No. 11 or Japanese Patent Application No. 5-265857 was made.

[0003]

However, in the above-mentioned prior invention, the auxiliary strengthening particles were only intermetallic compounds, and there was a problem that the strength near room temperature was insufficient. Here, if the oxide particles can be compounded by a mechanical alloying (hereinafter, referred to as MA) method, it is expected that the strength can be improved. However, when a submicron or smaller oxide, for example, is complexed by the MA method at a high volume ratio from the stage of the starting material, there is a problem that aggregation of the oxide particles is likely to occur and the uniformity is also likely to decrease, and Such oxide fine powder is difficult to handle and is wasteful in terms of cost.

Therefore, the object of the present invention is to combine the oxides generated during the manufacturing process with the auxiliary strengthening particles without using the oxide particles of submicron or less from the stage of the starting material, and to obtain a high strength aluminum alloy. (Powder) and its manufacturing method.

[0005]

In order to solve the above problems, the gist of the present invention is pure aluminum powder or aluminum alloy powder; or this, and ceramic powder (excluding oxide powder) and intermetallic compound powder. MA is applied to a mixture of at least one auxiliary reinforcing particle powder selected from the group consisting of: and a precursor composite powder, and a part of the constituent elements in the MA powder is subjected to the MA treatment step, or A method for producing a high-strength aluminum alloy powder, which comprises partially oxidizing after the treatment and dispersing the resulting oxide as strengthening particles, a powder obtained by the method, and a high-strength aluminum produced using the powder. It is in alloy.

That is, according to the present invention, the step of discharging the powder of MA in an inert gas atmosphere to the atmosphere is repeated a plurality of times to mainly crush the oxide film formed on the powder surface during discharging. And a method for producing an aluminum-based oxide dispersion-reinforced composite material powder (hereinafter referred to as method A), which is characterized in that it is simultaneously compounded in an aluminum matrix, and an aluminum-based oxide dispersion-reinforced composite produced by the method (A). A material powder (high strength aluminum alloy powder) is provided.

The present invention also provides an aluminum-based oxide dispersion strengthened composite material (high-strength aluminum alloy) obtained from the high-strength aluminum alloy powder by a series of manufacturing steps.

The aluminum-based oxide dispersed in this material has the following specifications. Oxide: mainly Al ₂ O ₃ (alumina) Size: 1 μm or less Content: 10 wt% (wt%) or less in total Here, the oxide has a stronger reducing property than Al (it is easily oxidized)
When the constituent elements of the MA powder include Mg and Ca, or Zr or the like at almost the same level, MgO, CaO, and ZrO ₂ respectively.
Will also be the subject. As a rough guide, the standard free energy of formation of oxides at 500 ° C. is | ΔG ₀ | ≧ 220,0
It is an oxide of 00 Cal / g · mol · O ₂ .

In the method A according to the present invention, the oxide to be the reinforcing particles is not used as the starting material for MA, but is generated in the processing step of the method A and finely and uniformly dispersed in the matrix.

The present invention also includes the case where an auxiliary reinforcing particle powder is used in combination. Here, the auxiliary reinforcing particles include ceramic particles such as nitrides and borides, or intermetallic compound particles.

In addition to the method A, the present invention further includes MA supplied while injecting air supplied from an air compressor or the like or a mixed gas of air and an inert gas from a cylinder into the MA container.
The method (referred to as method B) is performed.

In the present invention, when the auxiliary reinforcing particles are used in combination, the composite ratio is 40 wt% or less and the size is 10 μm or less. In the present invention, alcohol may be used as a dispersant during the MA process, but the (carbon) content in the raw material needs to be 1 wt% or less.

Next, the high-strength aluminum alloy (powder) and the method for producing the same according to the present invention will be described in more detail with reference to the flow chart shown in FIG.

[0014] In weighing the materials (and mixtures) (figure 101) the present invention, the raw material for obtaining a high-strength aluminum alloy (powder) (starting material) is a pure Al powder becomes a matrix or Al alloy powder or, Alternatively, the powder is used in combination with auxiliary reinforcing particles. The purity of the pure Al powder is 99.5% or more, preferably 99.9% or more. In the case of Al alloy powder, Mg, Zn, Cu, Si, Cr, Mn, Fe, T
At least one element of i, Ni, and Zr is contained in an amount of 10 wt% or less in total, and the rest has an alloy composition of Al and inevitable impurities. Both have a particle size of 150
It is preferably μm or less.

On the other hand, as the auxiliary reinforcing particles, in the case of ceramic powder (particles), nitrides (Si ₃ N ₄ , TiN, A
1N, etc.), borides (TiB ₂ , etc.), etc. can be used.

The intermetallic compound particles used as the auxiliary reinforcing particles include, for example, Japanese Patent Application No. 5-22531.
The intermetallic compound or precursor composite powder disclosed in Japanese Patent Application No. 1 and Japanese Patent Application No. 5-265857 is particularly suitable.

Among these, Japanese Patent Application No. 5-225311 discloses an intermetallic compound dispersion strengthened aluminum alloy which comprises mixing Al powder or Al alloy powder with intermetallic compound powder and subjecting the mixed powder to MA treatment. It is an alloy obtained by treating the powder obtained by the method for producing powder, but the above intermetallic compound powder used here can also be used in the present invention. The following are listed as intermetallic compounds. (1) For the purpose of pursuing lightweight and high strength (specific gravity in parentheses): Mg ₂ Si (1.96), Al ₃ Ti (3.3), Ti
Al (3.8) etc. (2) When pursuing improvement of high temperature strength: Al ₃ V, Ni ₃ Al, Al ₃ Ni, Al ₃ Fe, Fe
Al ₃ Zr, Al ₃ Mn, Al ₃ Ti, etc. (3) For the purpose of pursuing high strength and low cost: Mg ₂ Si, CuAl _{3 Japanese} Patent Application No. 5-265857 is a metal that serves as reinforcing particles. A powder of each constituent element of the intermetallic compound (for example, a constituent element of the compound of the above (1) to (3)) is weighed and mixed according to the stoichiometric composition, and the mixed powder is mechanically alloyed to obtain a precursor composite. Pure Al powder or Al on the body
An alloy obtained by treating a powder obtained by a method for producing an aluminum alloy powder in which a precursor composite is formed by adding alloy powder and performing MA again. The above-mentioned precursor composite used here is It can also be used in the present invention.

When the ceramic powder is used, its size is preferably 1 μm or less. In the case of powder of intermetallic compound or precursor composite, size of 106 μm or less is preferable. This is because crushing occurs over time as the MA progresses.

In this step (101), the raw materials are weighed. When auxiliary reinforcing particles are used, or when they are mixed with pure Al or pure Al powder, the ratio is 40 wt% by weight.
Below. If it is 40 wt% or more, the toughness is extremely reduced, and it cannot be put to practical use.

Mechanical alloying (1A2, 1 in the figure)
B2) Method A is, after 101, 1A2, 1A3, 1 in FIG.
A4, 105, 106, 107, 108, and 109 are carried out in this order. Method B is 1B after 101 in FIG.
2,1B3,105,106,107,108,109
It is carried out in the order of. The substantial difference between the two methods is that mechanical alloying is performed in an inert gas atmosphere (1A2).
Whether it is performed in an oxidizing atmosphere while injecting air or a mixed gas of air and an inert gas (1B2).

In the present invention, the mixed powder is ball-milled, and MA is performed preferably using a high energy type attritor (1A2, 1B2). An example of the attritor is shown in FIG. In the attritor 1 of FIG. 2, the rotation of the shaft 2 causes the agitator 3 to rotate, which causes the ball 4 to move. MA is performed on the raw material by the movement of the ball 4. During MA processing, gas is introduced from the gas inlet 5 to keep the atmosphere in the processing container constant. Further, cooling water is introduced from the water inlet 6 to keep the temperature constant. In FIG. 2, 7 is a gas outlet and 8 is a water outlet. The maximum number of balls 4 is 1
It is preferably an inch, preferably a 3/8 inch steel ball. The ratio of the total weight of the balls to the powder added is 150: 1 to 20: 1, preferably 140: 1 to 40: 1, the ratio of the total weight of the balls to the total weight of the powder. Shaft 2
The rotation speed of is preferably 250 rpm. In the case of Method A, the atmosphere in the processing container is Ar, He, N ₂
Etc. in a non-oxidizing atmosphere. In the case of Method B, it is performed in an oxidizing atmosphere while injecting air or a mixed gas of air and an inert gas. The peripheral speed of the tip of the agitator 3 is 3.5.
It is necessary to perform the treatment at a speed of m / sec or less and a time of 20 hours or less, preferably 10 to 15 hours, using a ball of 1 inch at the maximum. Costs rise within 20 hours,
Fe mixes in to reduce the elongation of the finished product. As the balls 4, various kinds of balls such as WC type super hard balls, ZrO ₂ type or SiN ₄ type ceramics can be used in addition to steel balls. In addition, at the time of mechanical alloying,
Considering the dispersibility of the powder or the lubricating effect, an appropriate amount of methanol or ethanol is added as a dispersant. The addition amount is [dispersant amount (ml) / total powder weight (g)] × 100 = 1
Set to ~ 5. However, 1 to 5 is preferable for methanol and 1 to 3.5 is preferable for ethanol. When the amount of the dispersant is small, pure Al adheres to the ball surface in the attritor, and sufficient mechanical alloying cannot be performed. On the contrary, if the amount is too large, the treated powder becomes too fine and is rapidly oxidized and ignited after being discharged.
Not only a powder recovery device in an inert gas atmosphere or a vacuum is required, but also briquette molding needs to be performed in a non-oxidizing atmosphere, resulting in high cost. Further, as the particles become finer, the surface area becomes larger and the amount of oxidation also increases, and the carbon that remains as a residue reacts with Al to form aluminum carbide and embrittle the material. It is preferable that the amount of carbon mixed from the alcohol residue is 1% by weight or less.

As described above, in the method A, the inside of the processing container in the MA is kept in an atmosphere of an inert gas such as argon and the crushing / dispersion / compositing of the powder is mainly performed while suppressing the oxidation of the MA powder.
Perform A. Therefore, the method A is a particularly effective method for MA when compounding pure Al powder and auxiliary reinforcing particles or Al alloy powder and auxiliary reinforcing particles. Further, this method is a particularly effective method when an intermetallic compound or a precursor composite thereof is used for the auxiliary reinforcing particles. This is because these auxiliary reinforcing particles used as the starting material are generally coarse particles in many cases, and it takes a comparatively long time to be finely crushed and uniformly dispersed / complexed in the aluminum matrix. B
Then, only the amount of oxidation increases abnormally before this uniform dispersion / composite is achieved.
As indicated by B in the above, adhesion easily occurs at the bottom of the container and
This is because it is difficult to obtain uniform MA powder by discharging. In particular,
When using a precursor composite that still has ductility, this aggregation is likely to occur, and the MA is dissolved multiple times to eliminate the aggregation, resulting in a uniform M
A powder is obtained. In the case of an intermetallic compound or its precursor complex, Method A is advantageous because it has high activity and burns when it is pulverized in an oxidizing atmosphere.

On the other hand, MA is performed by forcibly injecting air or a mixed gas of air and an inert gas into the MA processing container (method B), mainly using pure Al powder or Al alloy powder as the starting material. It is advantageous to use the stable oxide particles even if the auxiliary reinforcing particles are used together, including safety. Alcohol is often used as a dispersant in MA, and this has the effect of vaporizing and shielding MA powder. Therefore, unless the above-mentioned gas is forcedly sent into the container, the progress of oxidation of MA powder is delayed. .

Emission (1A3, 1B3) Emission is to be conducted into the atmosphere in principle. In the case of Method A, if the MA powder is remarkably refined (average grain size of 15 μm or less), it may be ignited at the moment of discharge, so that the MA powder and the inside of the container should be cooled sufficiently. It is preferable that the recovery container also has a cooling function.

Evaluation of MA Powder (1A4, Method A Only) The MA powder obtained by Method A is in the state shown in FIGS. 3 and 4. FIG. 3 illustrates a case where auxiliary reinforcing particles are used as a starting material and the number of discharges is one. In this state, an oxide film formed by contact with the atmosphere during discharge after MA is formed around each powder particle, and the amount of oxide particles slightly mixed in MA is not sufficient. In FIG. 4, MA is performed a plurality of times. Oxide due to crushing / dispersion of oxide film is dispersed at a sufficient ratio. The MA powder obtained by the method B also resembles the properties of the MA powder when discharged a plurality of times by the method A. Here, in the evaluation of MA powder of Method A (1A4), whether to re-use MA or to move to a subsequent hot working step or the like is as shown in Table 1. In method A, MA is satisfied until this criterion is satisfied.
Repeat.

[0026]

[Table 1]

Classification (105) The discharged powder is classified, and MA powder of 300 μm or less, preferably 106 μm or less is used thereafter.

Billet molding (106) Mechanical alloying powder is put in a closed mold and compressed to obtain a block body by billet molding. The shape is a shape suitable for extrusion, for example, a cylindrical shape.

Canning (107) The block body is sealed in an aluminum can and degassed (canning). This is not absolutely necessary.

The degassed (108) billet is heated in a vacuum heat treatment furnace for degassing. 40
It is performed at 0 to 500 ° C. for 3 hours or more.

Hot plastic working (109) A material (complete alloy product) is produced by hot working the billet that has been degassed. A typical method is hot extrusion. It is carried out at 400 to 550 ° C. and an extrusion ratio of 5 or more, preferably 10 or more. In addition, hot isostatic press (H
I) and powder forging method.

The obtained material is given a shape by machining or hot forging method to obtain a product.

[0033]

EXAMPLES Example 1 (Method A) Using Al powder having a purity of 99.99%, Al ₃ Fe powder as auxiliary reinforcing particles, and using the attritor of FIG.
Method A was carried out according to the flowchart in FIG. As conditions for MA using the attritor shown in FIG. 2, with respect to Sample 1, the agitator rotation speed was 250 rpm, discharge was carried out for 4 hours, and discharge was carried out again at 250 rpm for 1 hour. Sample 2 was performed at 250 rpm for 5 hours, and M
A was not done. The composition ratio of this aluminum alloy powder is as shown in Table 2.

[0034]

[Table 2]

To the alloy powder obtained by the above MA,
The steps 105 to 109 in FIG. 1 were performed to obtain an aluminum alloy. The specific gravity of the alloy obtained by the sample 1 is 2.9.
3, the specific gravity of the alloy obtained by the sample 2 was 2.90.

The tensile strength (MPa) and hardness of Samples 1 and 2 are as shown in Tables 3 and 4.

[0037]

[Table 3]

[0038]

[Table 4]

As can be seen from Table 3, MA.
By repeating the discharge, it can be seen that the strength increased significantly without increasing the specific gravity.

5 and 6 show metallographic diagrams of Samples 1 and 2. It is understood that the sample 1 has the Al ₂ O ₃ particles of 1 μm or less dispersed more preferably. FIG. 7 illustrates FIG.

Example 2 (Example of Method A Using Precursor Complex) Using Al powder having a purity of 99.99%, the precursor complex described in Japanese Patent Application No. 5-265857 as auxiliary reinforcing particles. Was used. Further, the experiment was performed according to the flowchart of FIG. 1 using the attritor of FIG. That is, the powder (M of the constituent elements of the intermetallic compound (Mg ₂ Si) that becomes the reinforcing particles
(g and Si) were weighed and mixed according to the stoichiometric composition (molar ratio 2: 1), and the mixed powder was mechanically alloyed to obtain a precursor composite powder. This powder is a mechanical alloy of Mg and Si,
It is not yet an intermetallic compound.

The conditions for mechanical alloying of Samples 3 to 5 of Example 2 are shown in Table 5 below.

[0043]

[Table 5]

The ratio of pure Al powder and Mg ₂ Si (precursor composite) was set to Al-20 wt% (Mg ₂ Si (20 wt% Mg ₂ Si based on the total amount of the alloy) (after MA)).

For each sample, C in the powder after MA completion
The contents of (carbon) and Al ₂ O ₃ were as shown in Table 6 below.

[0046]

[Table 6]

In addition, the obtained MA powder was added with 105-1 in FIG.
The strength and hardness of the material obtained by applying the process of No. 09 were as shown in Tables 7 and 8.

According to the present Example 2, it is understood that even when the precursor composite powder of the intermetallic compound is used as the auxiliary reinforcing particles of the starting material, the strength can be greatly increased by applying the method shown in the present invention. It

[0049]

EFFECTS OF THE INVENTION The effect of the present invention is to discharge the MA-treated powder, expose it to the atmosphere to oxidize the surface, and then perform MA again (method A), or perform MA while oxidizing (method B). The contents of. (1) The strength is remarkably increased, especially at room temperature. (2) In Method A, the coagulation of the auxiliary reinforcing particles is eliminated by performing the MA again, and uniform MA powder is obtained, so that the uniformity of the material is improved. (3) Since the crushed material of the oxide film on the powder surface is used as the reinforcing particles, it is possible to strengthen the dispersion by using extremely fine particles. Therefore, even if the compounding ratio is small, the bulk becomes large, and therefore the weight of the material does not increase so much while showing a large reinforcing effect. (4) As described above, since the size of the crushed coating (oxide coating) is extremely small and dispersed in a large volume, it does not act as a hard spot during cutting and is generally easy to cut. Become. As for the tool, a conventional tool steel is sufficient. (5) It is not necessary to use a submicron-sized oxide powder at a high volume ratio as a starting material, and it is possible to prevent the generation of such powder aggregates.

As described above, the high-strength aluminum alloy obtained by the present invention is lightweight, has high strength, and is excellent in heat resistance, so that it can be applied to vehicle engine parts, brake disc rotors, and the like. It also has excellent wear resistance and can be applied to compressor vanes.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a process according to the present invention.

FIG. 2 is a conceptual diagram illustrating an attritor used in an embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating a structure of particles discharged after MA is performed by performing method A.

FIG. 4 is a conceptual diagram illustrating the structure of particles discharged after performing method A and performing MA multiple times.

5 illustrates the structure of the powder of Sample 1 of Example 1 60
It is a 0X micrograph.

FIG. 6 illustrates the powder structure of Sample 2 of Example 1 60
It is a 0X micrograph.

FIG. 7 is a schematic structural diagram illustrating the structure of the powder in FIG.

[Explanation of sign]

 1 Attritor 2 Shaft 3 Agitator 4 Ball 5 Gas inlet 6 Water level inlet 7 Gas outlet 8 Water outlet

[Table 7]

[Table 8]

Claims (3)

[Claims] 1. Pure aluminum powder or aluminum alloy powder; or at least one selected from the group consisting of ceramic powder (excluding oxides), intermetallic compound powder, and precursor composite powder. Mechanical alloying is applied to the mixture of auxiliary reinforcing particle powder and
A method for producing a high-strength aluminum alloy powder, which comprises partially oxidizing a part of the constituent elements in the mechanical alloying powder during or after a treatment step and dispersing the resulting oxide as reinforcing particles. 2. A high-strength aluminum alloy powder obtained by the manufacturing method according to claim 1. 3. A high-strength aluminum alloy obtained by treating the high-strength aluminum alloy powder obtained by the manufacturing method according to claim 1.