JPH07258702A - Aluminum alloy reinforced by dispersing intermetallic compound, its powder and its production - Google Patents

Abstract

PURPOSE:To reduce the production cost of Al alloy reinforced by dispersing intermetallic compound by weighing powders of constituent elements, mixing them with Al powder and subjecting the resultant mixture to mechanical alloying treatment. CONSTITUTION:Powders of elements A, B are weighed in accordance with the stoichiometric compsn. of the constituent elements of an intermetallic compd. acting as reinforcing particles and they are mixed to prepare a powdery mixture I. This mixture I is mixed with Al powder weighted as an element for a matrix. The resultant powdery mixture II is subjected to mechanical alloying treatment, discharged, classified, compacted into a billet, degassed and subjected to hot plastic working typified by hot extrusion. Toughness of the alloy can be improved by this method.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a high temperature range (300 to 50).
The present invention relates to a light weight and high strength intermetallic compound dispersion strengthened Al alloy (powder) having a significantly higher strength than conventional Al alloy wrought materials even at 0 ° C., and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Examined Patent Publication No. 3-20452, ceramic particles are incorporated as reinforcing particles into an Al alloy, or as disclosed in JP-A-3-72047, Mg powder is replaced with Mg ₂ Si particles. It is known that Al-Mg-Si powder is mixed or prepared by an atomizing method and the alloy is incorporated into an Al matrix.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the case where ceramic particles are dispersed and strengthened in an Al matrix,
There is a drawback in that the hardness of 1 and the ceramic particles are too different, so that the machinability of the reinforced material is significantly deteriorated. In addition, there is a problem in the wettability between the Al matrix and the reinforcing particles, so that the particles are often aggregated and the strength is greatly varied, so that the sufficient reinforcing effect may not be obtained. In addition, although hardness and tensile strength are improved, elongation is drastically reduced and impact value and fracture toughness value are also reduced.
There is a possibility that the reliability of the material may be impaired. There is also a problem that hot working such as hot extrusion is difficult. Many of the matrices use pure Al, and many do not show sufficient strength in a high temperature range of 300 ° C. or higher.

On the other hand, the one using Mg ₂ Si powder (or intermetallic compound powder) as a reinforcing material has a drawback that the cost is heavy because it itself is expensive. In addition to Mg ₂ Si, when the intermetallic compound used for the reinforcing material is one containing a high melting point element, it is difficult to use the atomizing method, and the desired component composition cannot be obtained. It was difficult to disperse the compound uniformly. Therefore, the present inventor first creates a precursor composite powder that can later become an intermetallic compound in an Al matrix, and then creates an Al alloy powder in which the precursor composite powder is uniformly and finely incorporated in Al, The above problems were solved by developing and proposing a technique for forming an intermetallic compound dispersion strengthened Al alloy by hot plastic working this. It is an object of the present invention to provide an intermetallic compound dispersion-strengthened Al alloy (powder) that further improves this proposal and simplifies the manufacturing process, and a manufacturing method thereof.

[0005]

According to the present invention, in accordance with the above object, the powders of the respective constituent elements of the intermetallic compound to be the reinforcing particles are weighed so as to have a stoichiometric composition. At the same time, the above problems were solved by providing a method for producing an Al alloy powder by mixing this with pure Al powder or Al alloy powder and subjecting this to mechanical alloying treatment. Further, according to the present invention, as described in claim 4, the Al alloy powder obtained according to any one of claims 1 to 3 is processed by a subsequent step including billet forming and hot working to obtain a metal. The above problems were solved by providing a method for producing an intermetallic compound dispersion strengthened Al alloy that obtains a material in which an intermetallic compound is uniformly and finely dispersed. Further, the present invention is
The above problems are solved by using an intermetallic compound dispersion strengthened Al alloy manufactured by the manufacturing method of claim 4 as described in claim 5. The present invention simplifies the manufacturing process of an intermetallic compound dispersion strengthened Al alloy.

A method for producing an intermetallic compound dispersion strengthened Al alloy according to the present invention will be described below with reference to FIG.
First, each constituent element A of the intermetallic compound that becomes the strengthening particles,
B, C ... (Normally two or more types. Here, A,
The case of B2 element will be described. ) Each powder is prepared. Next, powders of the elements A and B2 are weighed and mixed according to the target stoichiometric composition of each constituent element of the intermetallic compound to prepare a mixed powder I. Here, the stoichiometric composition means the chemical composition originally represented by the structural formula, and for example, in the case of Al ₃ Ti, the composition ratio of Al atoms and Ti atoms is 3: 1, that is, Al -25 at (atom)% Ti is Al ₃ T
The stoichiometric composition of i means that if Mg ₂ Si, then Mg
And Si is 2: 1, Mg-33.3 at% Si has a stoichiometric composition. This stoichiometric composition AB is
Even if the composition is shifted to either the B side or the B side, an intermetallic compound having the stoichiometric composition AB is generated in the subsequent hot working and exhibits a strengthening effect. Therefore, about 10 wt% around this stoichiometric composition AB is a composition range showing significance. For example, if B element is added based on A element and Xwt% is stoichiometric composition AB,
A- (X-10) wt% to A- (X + 10) wt% are significant. Next, the mixed powder I is 40% by weight of the whole.
Pure Al powder or Al alloy powder is weighed as a matrix element as described below, and this is added to the mixed powder I and mixed to prepare a mixed powder II. If the mixed powder I is 40% by weight or more of the whole, workability such as extrusion is deteriorated and impact value is also decreased, which is not preferable. If the amount is too small, the original strengthening effect cannot be obtained. Further, the reinforcing particles used in the present invention need to be an element having excellent friability, and for example, Si is used. If the crushability is poor, fine powder having a preferable quality cannot be obtained. Further, the present invention is effective when the ratio of the Al powder used is 90 atomic% or less of the whole. If it is more than this, a desirable result cannot be obtained.

Next, the mixed powder II is subjected to a ball mill treatment, preferably a mechanical alloying treatment using a high energy type attritor. An example of this 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. The raw materials are mixed by the movement of the balls 4. During the mixing operation, gas is introduced from the gas inlet 5 to keep the mixed atmosphere constant. Further, cooling water is introduced from the water inlet 6 to keep the temperature constant. In addition, 7 is a gas outlet, 8
Is the water outlet. The ball 4 is preferably a steel ball having a maximum size of 1 inch, preferably 3/8 inch. The rotation speed of the shaft 2 is preferably 250 rpm. The mixed atmosphere is a non-oxidizing atmosphere using Ar, He or the like. The peripheral speed of the tip of the agitator 3 is 3.5 m /
Within 20 seconds, using a 1-inch ball at the maximum, 20
It is necessary to carry out the treatment within a time of preferably 10 to 15 hours. Cost rises over 20 hours and Fe
Mixes in with the product and reduces the growth of the finished product.

The mechanical alloying is carried out by adding an appropriate amount of methanol or ethanol as a dispersant in consideration of the dispersibility of powder or the lubricating effect. The amount added is [dispersant amount (ml) / total powder weight (g)] × 100 = 1.
Set to ~ 5. When the amount of the dispersant is small, pure Al adheres to the ball surface in the attritor, and sufficient mechanical alloying treatment 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. Therefore, not only an inert gas atmosphere or a vacuum powder recovery device is required,
It is necessary to perform briquette forming 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. 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 residue of alcohol is 1% by weight or less.

After the above steps, the powder is discharged. The powder thus discharged is classified, and powder finer than 48 mesh is used thereafter. Preferably, it is finer than 150 mesh. Next, this mechanical alloying powder is filled in a closed mold and compressed to form a billet.
The shape is a shape suitable for extrusion, for example, a cylindrical shape. Next, this billet is heated in a vacuum heat treatment furnace to degas.
Since there is adsorbed moisture or hydroxide on the powder surface and gas is generated during heating, degassing of the formed billet should be sufficient. Usually, it is carried out at 350 to 500 ° C. for 2 hours or more. A material (complete alloy product) is produced by subjecting the degassed billet to hot plastic working. A typical method is hot extrusion. It is carried out at 410 to 500 ° C. and an extrusion ratio of 5 or more, preferably 10 or more. At the time of heating and plastic deformation, a reaction occurs due to frictional heat between adjacent powders and the like, and an intermetallic compound is dispersed and generated in the Al matrix.
That is, the powder mechanically alloyed by the mechanical alloying process reacts in the steps from billet forming to hot working to obtain a raw material in which the intermetallic compound is finely dispersed in the Al matrix. . The total amount of oxygen after hot working depending on the amount of oxidation of the alloy powder is set to 5% by weight or less. This is because if the amount of oxidation exceeds this, the elongation decreases, the extrudability deteriorates, and it becomes difficult to perform hot working for imparting shape later.

[0010]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. As an example, an intermetallic compound dispersion strengthened Al alloy in which Mg ₂ Si is dispersed in reinforcing particles will be described with reference to FIG. First, pure M
g, each powder of pure Si was prepared, and each powder described above was weighed so as to be Mg-38 wt% Si, which is the stoichiometric composition of Mg ₂ Si. In this example, Mg = 37.2 g, Si
= 22.8 g, and a total of 60 g was prepared. As the Mg powder, one having a purity of 99.9% or more and a particle size of 100 mesh or less was prepared. Pure Si powder has a purity of 98% or more and a particle size of 2
The one having 50 mesh or less was used. At the same time, the pure A described above
240 g of 1 powder was prepared and mixed well. next,
This mixed powder was put into the apparatus shown in FIG. 2 and mechanically alloyed. That is, the agitator rotation speed is 25
At 0 rpm, 5.5 cc of methanol was added,
Processed over time. After cooling, the treated powder was discharged. 1.2 cc of methanol was added prior to discharge. Next, the powder having a particle size of 106 μm or less was classified, and thereafter, the powder was used. next,
This powder is formed into a billet, and the vacuum atmosphere is 6 × 10 ⁻³ To.
heating at a temperature of 400 ° C. under rr for 5 hours,
Degassing treatment was performed. The billet that had been degassed was hot extruded at an extrusion ratio of 10 and a temperature of 450 ° C. to obtain a raw material.

[Comparative Example] A method of preparing a precursor composite powder that can be an intermetallic compound, which has been developed earlier, and then processing by mixing with Al powder is used as a comparative example, and this is referred to the process shown in FIG. However, it will be described below. First, 37.2 g of Mg powder and 22.8 g of Si powder having the same quality as those in the above-described embodiment are prepared and mixed. Next, only this mixed powder is mechanically alloyed. 250 rpm agitator rotation speed
m, 3 cc of methanol was added, and the mixture was treated for 3 hours. By this treatment, Mg and Si are converted into Mg ₂ S
A precursor composite powder that can be i was obtained. Next, 240 g of pure Al powder having the same quality as that of the example was put into the Mg ₂ Si precursor composite powder in the attritor and mixed. Then, the mixed powder was subjected to mechanical alloying treatment again. At an agitator rotation speed of 250 rpm, 2 cc of methanol was added and the mixture was treated for 2 hours. After cooling, the treated powder was discharged. 0.5 cc of methanol was added prior to discharge. Next, this powder was used in the same manner as in the example to obtain a particle size of 10
Particles having a size of 6 μm or less were classified and used thereafter. Similarly, after forming a billet with this powder, degassing treatment was carried out at a temperature of 350 ° C. for 3 hours in a vacuum atmosphere under the same conditions. Then, hot pressing was performed under the same conditions as for the billet that had been degassed to obtain a comparative material.

The physical properties of the examples and comparative examples obtained by the above treatment were compared, and the following results and conclusions were obtained.
First, the results of X-ray diffraction of the mechanical alloying powder and the material extruded using the powder in Example are respectively shown in FIG.
As shown in FIG. In the powder state shown in FIG. 4, Al, Mg, S
Only each peak of i is observed, and Mg which is an intermetallic compound
It can be seen that the formation of ₂ Si did not occur. On the other hand, after hot extrusion in FIG. 5, the peaks of Al, Mg ₂ Si, and Si are recognized, and it can be seen that the reaction of 2Mg + Si → Mg ₂ Si occurs. Next, FIGS. 6 and 7 show the metallographic structures which are magnified 400 times that of the examples and comparative examples. Mg less than 1 μm
₂ Si and up to 3μm or less of Si are uniformly dispersed,
It turns out that they have almost the same organization. Table 1 shows the values of the tensile strength, elongation and hardness of the examples and comparative examples.

[0013]

[Table 1]

According to Table 1, the physical properties at room temperature (RT), that is, the tensile strength, elongation and hardness, are almost the same. On the other hand, in the high temperature range (300 ° C.), the elongation of the example according to the present invention is significantly higher than that of the comparative example.
Therefore, it was confirmed that the present invention is suitable as a material requiring elongation at high temperature.

[0015]

According to the present invention, the following effects can be obtained. That is, since the process for manufacturing the precursor composite, which is performed in the comparative example, can be omitted, the process is simplified. As a result, the time for mechanical alloying processing can be shortened, and the manufacturing cost can be reduced. Further, since the powder is less likely to be oxidized, the toughness can be improved. Since the constituent elements of the raw material are mixed at the same time, a large difference does not occur between the adjusted composition ratio and the component composition ratio of the manufactured extrusion material. That is, it is easy to obtain a material having a target composition. Then, an excellent elongation at high temperature can be obtained. Further, in the step of passing through the precursor composite of Mg ₂ Si, the precursor composite easily aggregates. In this case, the discharged mechanical alloying powder can be improved by subjecting it to mechanical alloying treatment again, but in the present invention, such agglomeration does not occur. Therefore, A in which Mg ₂ Si particles are dispersed
This is a more advantageous method for producing an 1-alloy.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of an attritor used in an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a manufacturing process according to the present invention.

FIG. 4 is an X-ray diffraction chart of the powder of the example.

FIG. 5 is an X-ray diffraction chart of the material after hot working according to the same example.

FIG. 6 is a photograph as a drawing substitute for a metallographic structure of the material of the example.

FIG. 7 is a photograph as a drawing, which shows a metallographic structure of a material of a comparative example.

FIG. 8 is an explanatory diagram of a manufacturing process of a comparative example.

[Explanation of symbols]

 1 Attritor 3 Agitator 4 Ball

Claims (6)

[Claims] 1. A powder of each constituent element of an intermetallic compound which becomes a strengthening particle is weighed so as to have a stoichiometric composition, and this is mixed with pure Al powder or Al alloy powder, and mechanical alloying treatment is applied to this. A method for producing an Al alloy powder, comprising: 2. The method for producing an Al alloy powder according to claim 1, wherein the powder of each constituent element of the intermetallic compound is 40% of the whole.
A method for producing an Al alloy powder, characterized in that the content is less than or equal to wt% and the element is excellent in friability. 3. The method for producing an Al alloy powder according to claim 1, wherein alcohol is used as a dispersant during the mechanical alloying process, and the amount of carbon mixed from the residue of the alcohol is 1% by weight or less. And a method for producing an Al alloy powder. 4. The Al alloy powder obtained by any one of claims 1 to 3 is processed in a subsequent step including billet forming and hot working to uniformly form an intermetallic compound.
A method for producing an intermetallic compound dispersion-strengthened Al alloy, characterized in that a finely dispersed material is obtained. 5. An intermetallic compound dispersion strengthened Al alloy manufactured by the manufacturing method according to claim 4. 6. The total oxygen content of the material after hot working is 5% by weight.
The intermetallic compound dispersion strengthened Al alloy according to claim 5, wherein: