WO1992007676A1

WO1992007676A1 - Hypereutectic aluminum/silicon alloy powder and production thereof

Info

Publication number: WO1992007676A1
Application number: PCT/JP1991/001488
Authority: WO
Inventors: Yoshinobu Takeda; Tetsuya Hayashi; Toshihiko Kaji; Yusuke Odani; Kiyoaki Akechi
Original assignee: Sumitomo Electric Industries, Ltd.; Toyo Aluminium K.K.
Priority date: 1990-10-31
Filing date: 1991-10-31
Publication date: 1992-05-14
Also published as: EP0592665B1; EP0592665A4; DE69120299D1; EP0592665A1; DE69120299T2

Abstract

A hypereutectic aluminum/silicon alloy powder wherein a primary crystal of silicon has a grain diameter of as minute as 10 νm or less is produced by the atomization process which comprises preparing a melt of a hypereutectic aluminium/silicon alloy containing phosphorus and spraying the melt by means of air or an inactive gas to effect rapid cooling for solidification. The obtained alloy powder contains 12 to 50 wt% of silicon and 0.0005 to 0.1 wt% of phosphorus. This powder can provide a solidified powder with improved mechanical properties in a high yield without any limitation to the grain size.

Description

Specification

Hypereutectic aluminum-silicon alloy powder and method for producing the same

Technical field

The present invention relates to a hypereutectic aluminum-silicon-based alloy powder and a method for producing the same, and in particular, to a hypereutectic aluminum-silicon-based alloy powder having a stable fine silicon primary crystal. And its manufacturing method.

Background art

The addition of silicon (S i) to aluminum (A 1) has remarkable effects such as lowering the coefficient of thermal expansion, improving rigidity, and improving wear resistance. A1-Si-based alloys utilizing this effect have already been widely used.

Among such A11-Si-based alloys, steel materials are classified as AC or ADC according to the JIS standard, and are used in large quantities as aluminum alloys such as engine blocks. A1-Si-based alloys as wrought materials are classified into the 4000 series, and are added to various parts by extrusion, forging, etc. from forged billets.

It is well known that hypereutectic Al-Si alloys are produced by a sintering method. Hypereutectic A 1 -Si-based alloys obtained by sintering have excellent properties such as low coefficient of thermal expansion, high rigidity, high wear resistance, and are suitable for use in various fields. It is expected. However, hypereutectic A 1 -Si-based alloy The presence of large silicon primary crystals degrades their mechanical properties and machinability during machining.

It is also well-known that hyperfine eutectic A 1 —Si-based alloy ferrite is added with a refining agent, particularly phosphorus (P), in order to refine the primary crystal of silicon. However, even if a refiner is added during the production of a hypereutectic Al-Si alloy, the refinement of the primary crystal of silicon is limited. In particular, in the case of A1-Si alloys having a silicon content exceeding 20% by weight, coarse silicon primary crystals exist even when a refiner is added. The alloy's mechanical properties and machinability during machining are still poor.

On the other hand, in recent years, a rapidly solidified powder manufacturing method such as an atomizing method can produce a powder from a molten metal at a large cooling rate that was impossible with the melt-casting method. As a result, the primary crystal of silicon can be refined and contains silicon having a eutectic composition or more, and further, iron (Fe) and nickel (Ni) as the third alloy components. It is possible to produce hypereutectic A1-Si-based alloy powders containing transition metal elements X such as chromium (Cr) and manganese (Mn). As an alloy produced by powder metallurgy using these powders, Al — 17 S i — X, A 1-20 S i-X, A Powder metallurgy alloys such as 1-25Si-X have been put to practical use.

In order to further improve the mechanical properties of the powder metallurgy alloys described above, it is necessary to further refine the silicon crystals and to make the silicon crystal grain size uniform. In addition, It is extremely important to reduce the amount of coarse silicon crystals that cause fracture even at a small amount and cause variations in material strength. In addition, the primary silicon crystals in the powder are unlikely to become fine due to hot solidification such as forging or extrusion, but rather become coarse due to osto-growth. It was but connexion, Ru Shi Li co down decisively important size of primary crystal in the alloy powder _c

By the way, it is known that the primary crystal of silicon can be refined by increasing the cooling rate when producing powder. However, the cooling rate is largely determined by the atomizing method and equipment, and increasing the cooling rate by other industrial methods has not been realized due to economic and productivity problems.

In addition, in the conventional atomizing method, since the cooling rate depends on the particle size of the powder, as long as the obtained powder has a certain width of particle size distribution, the particle size of the existing silicon primary crystals in all powders There are large variations. For example, in the past, a coarse silicon primary crystal having a particle size of about 20 was unavoidable in a powder having a particle size of about 400 m.

Therefore, conventionally, in order to remove particles having coarse primary crystals of silicon, a coarse powder having a low cooling rate is sieved and removed, and a solidified body is produced using only the fine powder. Was being done. However, according to this method, the economic efficiency is deteriorated due to a decrease in the material yield, and the fluidity of the powder and In addition, there were problems such as the remarkable decrease in the handling properties such as the properties, and the increased risk of dust explosion.

The present invention has been made in view of the above-described conventional circumstances, and it has been found that the atomization method allows the silicon primary crystals to be fine and uniform, and particularly suppresses the crystallization of coarse silicon primary crystals. It is an object of the present invention to provide a possible hypereutectic A 1 —Si alloy powder composition and a method for producing the same.

Disclosure of the invention

In view of the above-mentioned problems of the prior art, the inventors of the present application have conducted various experiments and studies, and as a result, have found that an aluminum silicon-based material to which a primary crystal silicon refiner containing phosphorus is added is added. It is obtained by melting a molten alloy or an aluminum-silicon alloy ingot containing a phosphorus-containing primary crystal silicon refiner in advance. The molten alloy is prepared using air or an inert gas. It was found that by atomizing, an extremely fine hypereutectic aluminum-silicon alloy powder of primary silicon could be obtained.

In the hypereutectic aluminum-silicon alloy powder according to the first aspect of the present invention, silicon is contained in an amount of from 12% by weight to 50% by weight, and phosphorus is contained in an amount of 0.0005% by weight or more. Contains 0.1% by weight or less.

The particle diameter of the primary crystal silicon in the hypereutectic aluminum silicon-based alloy powder of the present invention is the same as that of the primary crystal silicon in the hypereutectic aluminum-silicon alloy obtained by the conventional fabrication method. Much smaller than the size, usually less than 10 m. The aluminum-silicon alloy powder of the present invention has a silicon content of 12% by weight or more and 50% by weight or less, preferably 20% by weight or more and 30% by weight or less. If the silicon content is less than 12% by weight, primary silicon does not crystallize. On the other hand, if the silicon content exceeds 50% by weight, the amount of primary crystal silicon is too large even if the primary crystal of silicon is refined no matter how much, and it was made from the obtained powder. The machinability of the solidified body is poor, and its mechanical strength is also poor.

The phosphorus content in the aluminum silicon alloy powder of the present invention is from 0.0005% to 0.1% by weight, preferably from 0.0005% to 0.05% by weight. It is as follows. If the content of phosphorus is less than 0.0005% by weight, no refining effect is obtained and no improvement in mechanical strength is observed. On the other hand, even if the phosphorus content exceeds 0.1% by weight, the effect of miniaturization is not further improved. In particular, aluminum-silicon alloy powder having a phosphorus content of 0.02% by weight or more and 0.1% by weight or less has excellent machinability during machining.

More preferably, concrete aluminum-silicon alloy powder of the present invention contains silicon in an amount of from 12% to 50% by weight, and copper in an amount of from 2.0% to 3.0% by weight. In the following, magnesium is 0.5% by weight or more and 1.5% by weight or less, manganese is 0.2% by weight or more and 0.8% by weight or less, and phosphorus is 0.005% by weight or more and 0.05% by weight. %, The balance being aluminum and unavoidable impurities. Copper, magnesium, and manganese sources Aluminum-silicon alloy powders containing silicon have higher mechanical strength.

According to the method for producing a hypereutectic aluminum-silicon alloy powder according to the second aspect of the present invention, first, a molten metal of a hypereutectic aluminum-silicon alloy containing phosphorus is prepared. . The molten metal is sprayed and rapidly solidified using air or an inert gas.

The melt of a hypereutectic aluminum silicon-based alloy containing phosphorus can be either a molten aluminum-silicon-based alloy to which a primary silicon-containing alloy refiner containing phosphorus is added, or a molten metal containing phosphorus. In the production method of the present invention, the primary silicon refiner containing phosphorus may be any molten alloy obtained by melting an aluminum silicon-based alloy ingot containing a crystalline silicon refiner in advance. For example, primary crystal silicon refining agents used in conventional manufacturing methods, such as Cu—8 wt% P, Cu

- 1 5 wt% P, PC i _5, mixed salt mainly composed of lights down like, or A 1 - C u- P refiner is used.

The primary crystal silicon refining agent is usually used in an amount of 0.0005% to 0.1% by weight, preferably 0.02% to 0.05% by weight. Is done. When the amount of the primary crystal silicon refiner is less than 0.005% by weight, the effect of the addition of the primary silicon refiner is not sufficient. Further, even if the primary crystal silicon refiner is added in an amount exceeding 0.1% by weight, no further improvement in the effect is observed. In the production method of the present invention, the aluminum silicon alloy melt is subjected to an atomizing treatment according to a known method.

In the production method of the present invention, the alloy melt is subjected to the atomizing treatment while being kept at a temperature of 100 ° C. or higher and 130 ° C. or lower than the liquidus temperature of the aluminum-silicon alloy. It is preferable. Even when the primary silicon refiner is added to the aluminum-silicon alloy, it is preferable to keep the alloy at the above temperature.

Here, the liquidus temperature means the temperature at which the alloy of the composition is completely melted. For example, the liquidus temperature of an aluminum-silicon alloy containing 25% by weight of silicon is about 780 ° C.

If the molten alloy is maintained at a temperature lower than the liquidus temperature of the aluminum silicon-based alloy at (liquidus temperature + 100), the dissolution of the phosphorus will be insufficient and the amount of added phosphorus will be insufficient. In contrast, the amount of phosphorus contained in the alloy is reduced, and it is difficult to obtain an alloy powder containing the correct amount of phosphorus. Also, if the molten alloy is kept at a temperature exceeding 1300 ° C, the crucible and the furnace material will be seriously damaged, and depending on the contained alloy element, it will partially evaporate and have the desired composition. An alloy may not be obtained.

More preferably, the molten alloy is kept at a temperature of 100 ° C higher than the liquidus temperature of the aluminum-silicon alloy and lower than 1300 ° C for at least 30 minutes. Later, the atomize process Manage. Even when the holding time is shorter than 30 minutes, the dissolution of the phosphorus is insufficient, and the amount of the phosphorus contained in the alloy becomes small relative to the amount of the added phosphorus. It is difficult to obtain an alloy powder containing the above amount. However, this is not the case when using the A 1 —Cu—P inoculant (retention time may be shorter than 30 minutes).

The aluminum-silicon alloy to which the method of the present invention is applied is not particularly limited, and elements other than aluminum and silicon, for example, magnesium, manganese, iron, nickel, zinc General aluminum silicon-based alloys containing the same may also be included. The production method of the present invention is particularly useful for aluminum-silicon alloys having a high silicon content (20 to 40% by weight).

As described above, according to the present invention, a hypereutectic aluminum silicon alloy powder in which extremely fine primary crystals are uniformly dispersed can be obtained. Further, when manufactured under the above preferable conditions, a hypereutectic aluminum-silicon alloy powder having a desired composition can be obtained.

The solidified body produced from the hypereutectic aluminum-silicon alloy powder of the present invention has extremely excellent machinability and mechanical properties.

According to the method for producing a hypereutectic aluminum silicon alloy powder according to the third aspect of the present invention, first, a molten metal of a hypereutectic aluminum-silicon alloy containing phosphorus is prepared. It is. The hypereutectic aluminum silicon-based alloy powder is produced by spraying and rapidly solidifying the molten metal using air. Only alloy powder with a particle size of 400 m or less is selected.

In the production method of the present invention, the inoculation method used in the melt-casting method is applied, and first, phosphorus is inoculated into a molten hypereutectic aluminum-double-silicon alloy for atomization.

By inoculating and dispersing the uniformly molten molten alloy with phosphorus, nuclei for solidification can be prepared in advance, and uneven nucleation due to supercooling can be suppressed. The inoculated phosphorus must be uniformly dispersed in the molten metal as solid particles at the spray temperature. At the same time, if undissolved components other than phosphorus are present in the molten metal, coarse crystals can easily be formed. The inoculated molten metal can be once cooled and solidified, then melted again and returned to the original inoculated molten metal state.

Next, the inoculum is sprayed by an air atomizing method and rapidly solidified. The air atomization method is used as a method for producing powder by rapid solidification because it is more economical than other methods and because the surface of the powder is stabilized by moderate oxidation, handling is easy. This is because there are advantages such as

It is known that the rapid solidification condition is that the higher the cooling rate, the finer the structure becomes. However, in the production method of the present invention, a large number of crystallization nuclei of silicon primary crystals are previously contained in the molten metal. The presence makes it possible to control the maximum crystal grain size of the primary silicon in a fine and narrow range with respect to the grain size of the obtained powder without strongly depending on the cooling rate which is difficult to directly control. In other words, fine and relatively uniform primary crystals of silicon can be obtained even at a lower cooling rate (the particle size of the obtained powder is relatively large) as compared with the conventional atomizing method. When the particle size of the obtained alloy powder is selected to be equal to or less than 400 // in, the maximum crystal grain size of the primary crystal silicon can be controlled to be equal to or less than 100 // m. Preferably, if the particle size of the obtained alloy powder is selected to be less than 200 zm, the maximum crystal grain size of primary silicon can be controlled to be 7 m or less. More preferably, if the grain size of the obtained alloy powder is selected to be 100 m or less, the maximum crystal grain size of primary silicon can be controlled to 5 m or less. If the particle size of the obtained alloy powder is selected to be 50 / zm or less, the maximum crystal grain size of primary silicon can be controlled to 3 zm or less.

In order to stably obtain the above-mentioned effects, the concentration of the inoculated phosphorus is preferably in the range of 0.05% by weight or more and 0.02% by weight or less.

As described above, according to the third aspect of the present invention, the primary crystal silicon of the hypereutectic aluminum-silicon alloy powder produced by the atomization method is refined and uniformized, The dependence of the primary crystal silicon particle size on the alloy powder particle size can be significantly reduced as compared with the conventional case. As a result, By using a crystalline aluminum-silicon alloy powder, it is possible to produce a solidified powder having improved mechanical properties at a high yield without restriction on the powder particle size.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a photograph of the crystal structure by an optical microscope showing the structure of primary silicon in the alloy powder obtained in Example 1.

(Magnification X 400).

FIG. 2 is a photograph of a crystal structure by an optical microscope showing a structure of primary crystal silicon in the alloy powder obtained in Comparative Example 1 (magnification: X400).

FIG. 3 is a photograph of the crystal structure by an optical microscope showing the structure of primary silicon in the forged alloy (magnification: X400).

FIG. 4 is an optical micrograph showing the metallographic structure of the hypereutectic aluminum 25-% by weight silicon alloy powder obtained in Example 3 and inoculated with phosphorus (magnification: X 40%). 0).

FIG. 5 is an optical micrograph (magnification: X400) showing the metal structure of the hypereutectic aluminum-125% by weight silicon alloy powder obtained in Example 3 but not inoculated with phosphorus.

FIG. 6 shows the relationship between the maximum grain size of silicon primary crystals in the hypereutectic aluminum alloy 25% by weight silicon alloy powder and the tensile strength at room temperature of the solidified body obtained from the powder in Example 3. It is a graph which shows a relationship.

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 A molten aluminum alloy having the composition shown in Table 1 was maintained at a temperature of 950 ° C, and Cu-8% by weight P was melted so as to obtain the phosphorus content shown in Table 1. Was added. After maintaining the molten metal at a temperature of 950 ° C. for 1 hour, the molten metal was pulverized by an air atomizing method (see alloy powders N 0.1 to N 0.4 in Table 1).

After classifying the alloy powder thus obtained into 142-180 mesh (175-350; particle size of m), the size of primary silicon in the powder was determined. It was measured by observing the structure with an optical microscope. The results are shown in Table 1. A micrograph of the alloy powder N 0.1 by an optical microscope is shown in FIG.

Comparative Example 1

Alloy powder N 0.5 was prepared under the same conditions as alloy powder No. 1. However, in this case, Cu—8% by weight of P was not added to the molten aluminum alloy.

After classifying the alloy powder obtained in this way into a mesh of 142 to 180 mesh (particle size of 175 to 350 m), the size of the primary crystal silicon in the powder is optically determined. It was measured by observing the structure with a microscope. The results are shown in Table 1. A micrograph of the alloy powder N 0.5 by an optical microscope is shown in FIG.

Comparative Example 1 A

Aluminum alloy having the same composition as alloy powder No. 1. Was maintained at a temperature of 950 ° C., and Cu—8 wt% P was added so that the phosphorus content shown in Table 1 was obtained. After holding at a temperature of 950 ° C. for 1 hour, the molten metal was poured into a mold having a diameter of 30 mm and a height of 80 mm to prepare an alloy material (No. 6).

The size of the primary crystal silicon in the thus obtained alloy material was measured by observing the structure using an optical microscope. The results are shown in Table 1. Fig. 3 shows a micrograph of the structure of the alloy alloy under an optical microscope.

From the comparison of the micrographs by the optical microscope shown in FIGS. 1 to 3, the size of the primary crystal silicon in the alloy powder obtained by the method of the present invention was determined by the size of the lithium obtained in Comparative Example 1. It is clear that the particles are finer and more uniformly dispersed than the size of the primary silicon in the alloy powder of the same composition, which does not contain copper.

(Hereinafter the margin)

Table 1 α composition Si primary crystal

Particle size

No.Si s u Mg Mn P ί m) Example 1 1 25 2.5 1.0.0 0.5 0.50 240 丄 to 5

2 25 3.5 0 0.5 0 0.5 0 0.0055 1 to 6

3 25 3.ό 1. 0 0, 0 0. 0545 1 to 5

4 25 2.5 1.0.5 0.50 125 1 to 5 Comparative Example 1 5 25 2.5 1.0.5 0.5 to 0.0005 3 to 20 Comparative Example 6 25 2.5 1.0.0 50.0240 5 to 80 Next, the machinability of the compacts made from the alloy powder and the alloy body obtained in the above Examples and Comparative Examples was tested.

After classifying the alloy powders No. 5 to No. 5 obtained in Example 1 and Comparative Example 1 into 142 mesh (350; particle size below), a pressure of 3 tons Z cm was applied. It was cold preformed into a size of 3 0 111 111 height and 800 111 111 height at ² . Thereafter, these compacts were hot extruded into a round rod having a diameter of 10 mm at an extrusion temperature of 450 ° C. and an extrusion ratio of 10. Similarly, the alloy product N 0,6 obtained in Comparative Example 1A was extruded into a round bar having a diameter of 10 mm.

The round bar extruded material thus obtained was dry-cut with a cutting speed of 100 mZ using a cemented carbide tool, and the wear of the tool after cutting for 10 minutes was measured. The results are shown in Table 2. Indicated Table 2 Tool wear (mm) Example 1 (alloy N 0.1) 0.0 3

Comparative Example 1 (Alloy N 0.5) 0.12

Comparative Example 1 A (structure N 0, 6) 1.01 From the results shown in Table 2, it is clear that the machinability of the compact produced from the alloy powder of the present invention is extremely excellent.

Example 2

As shown in Table 3, the molten metal obtained by dissolving the aluminum alloy metal containing phosphorus was kept at a temperature of 950 ° C for 1 hour. Thereafter, the molten metal was powdered by an air atomizing method (see Alloy powders No. 11 to No. 15 in Table 3).

After classifying the alloy powder thus obtained into 100 meshes (particle diameter of less than 147 μπι), the size of primary silicon in the powders was determined using an optical microscope. It was measured by observing the tissue. The results are shown in Table 3.

Comparative Example 2

Alloy powders No. 16 to No. 18 were prepared under the same conditions as alloy powders No. ll to No. 15. However, in this case, Aluminum alloy ingots that do not contain phosphorus were used.

After classifying the alloy powder thus obtained into 100 mesh (particle size of less than 147 / zm), the size of the primary silicon in the powder was determined using an optical microscope. It was measured by observing the tissue. The results are shown in Table 3. Table 3 Alloy composition Si primary crystal grain size

No, Si Cu Mg Mn P (m) Example 2 1 1 25 2.5 1 0 0.5 0.0041 1 ~: L 0

1 2 25 2.5 1 0 0.5 0.0116 1 ~: L 0

1 3 25 2.5 1 0 0.5 0.0395 1〜5

1 4 2δ 3.5 9 0 0.S 0.0075 1 ~ 1 0

1 5 25 2.δ 1 0 0.0 0.0152 1 ~ 1 0 Comparative example 2 1 6 2ό 2.a 1 0 0.5 <0.0005 1 ~ 2 0

1 7 25 3.5 2 0 0.5 <0.0005 1 ~ 2 0

1 8 25 2.5 1 • 0 0.0 Q.0005 1-2. Next, the transverse rupture strength of the alloy powders obtained in the above Examples and Comparative Examples was tested.

The alloy powders N 0.11 to N 0.18 obtained in Example 2 and Comparative Example were converted to 100 mesh (particle size of less than 147 / zm). After classification, cold preforming was performed at a pressure of 3 ton Z cm ² to a size of 30 mm in diameter × 80 mm in height. Thereafter, these compacts were hot extruded into a flat plate having a width of 2 mm and a thickness of 4 mm at an extrusion temperature of 450 ° C. and an extrusion ratio of 10. After the flat plate extruded material thus obtained was subjected to T6 treatment, the transverse rupture strength was measured at a gauge distance of 30 mm based on JISZ223. The results are shown in Table 4. Table 4

From the results shown in Table 4, it is clear that the die strength of the alloy powder containing phosphorus of the present invention is about 10% higher than that of the alloy powder containing no phosphorus. The alloy powder of the invention of No. 13 having a phosphorus content exceeding 0.02% by weight The force to lower the transverse rupture strength slightly compared to No. 16 of the alloy powder. It can be used sufficiently.

Example 3

The following hypereutectic aluminum-silicon alloys were prepared from metal.

A-17: 2 0 2 4 bullion + 1 7 wt% S i

A-20: 20 24 bullion + 20 wt% S i

A— 2 5: 2 0 2 4 bullion + 25 w t% S i

B— 2 5: 2 02 4 bullion + 25 wt% S i-5 w

% F e

C-25: 20 24 bullion + 25 wt% S i + 5 w t

% F e + 2 w t.% N i

D-25: Al + 25 wt.% S i + 2.5 wt.% Cu + 1 t.% M g + 0.5 t.% F e + 0.5 wt.% Mn

E-25: 99.9% purity A 1 bullion + 25 t.% S i Inoculate each of the above alloys with phosphorus at the ratio shown in Table 5 or release without inoculation Each alloy melt was rapidly cooled and solidified by spraying at a pneumatic pressure of 5 to 10 kgZmm ² by a pneumatic atomizing method.

The obtained alloy powder was continuously collected, classified by air, and further classified by sieving. The particle size of the silicon co down primary crystals of these alloy powders as a result of determining by quantitative image analysis microscope, the maximum particle diameter D _e of the powder particle size D _p and S i primary _crystal; the relationship first Table 5 shown in Table 5

S i Primary crystal maximum particle size D _{S j} (β m) Powder particle size Dp (^ m) 200 D Dp 100 D Dp 50 <D Dp

≤ 400 ≤ 200 ≤ 100 ≤ 50 Alloy P inoculation

Α-Π 0.008 w t.% 5 4 3 2

Α-Π None.1 5 8 7 5

A-20 0.008 w t.% 6 5 3 2

A-20 None 2 0 8 7 6

A-25 0.008 w t.% 8 5 3 2

A-25 None 2 0 1 2 6 5

B-25 0.012 w t.% 7 4 3 2

B-25 None 1 8 8 8 4

C-25 0.007 t.% 7 4.2 2 2

D-25 0.010 w t.% 8 5 2 2

E-25 0.015 wt.% 9753 The metal structure of the hypereutectic aluminum silicon alloy powder obtained by inoculating phosphorus with the above A-25 alloy is 400 times larger. It is shown in FIG. 4 by an optical micrograph. The hypereutectic obtained by inoculating phosphorus with the A-25 alloy The microstructure of the aluminum-silicon alloy powder is also shown in Fig. 5. In FIGS. 4 and 5, the dark gray area is the primary silicon crystal, the light gray area is the matrix, and the black area is the void / embedding resin area.

Next, cold pressing was performed without classifying the two powders obtained with or without phosphorus inoculation using the A-25 alloy. These compacts were subjected to degassing heat treatment at a temperature of 45 CTC for 30 minutes. Then, after preheating these compacts at the same temperature, they were forged at a surface pressure of 6 tons Z cm ² and subjected to a T6 heat treatment.

The mechanical properties of the solidified body of each of the obtained powders were measured. Table 6 shows the measurement results. Table 6

In addition, the hypereutectic aluminum mini-silicon alloy powder obtained for the A-25 alloy was classified based on the maximum grain size of the silicon primary crystal. For each of the classified powders, the tensile strength at room temperature of the solidified product of each powder produced under the same conditions as above was measured. The results of these measurements are shown in FIG. From the above results, according to the production method of the present invention, the size of the silicon primary crystal in the powder can be controlled to be small and extremely narrow, so that the coarse silicon crystal is used as a starting point. The resulting fracture is significantly reduced and the mechanical strength of the solidified powder is improved. In addition, even when cutting the obtained solidified body, effects such as stabilization and control of chipping and wear of the cutting tool can be obtained.

Industrial applicability

As described above, the compact produced from the hypereutectic aluminum-silicon alloy powder according to the present invention has extremely excellent machinability and mechanical strength. Therefore, it is useful as a part for various mechanical structures. Further, according to the method for producing a hypereutectic aluminum-silicon alloy powder of the present invention, the primary crystal silicon of the hypereutectic aluminum-silicon alloy powder can be made finer and uniform. The dependence of the primary silicon particle size on the powder particle size can be significantly reduced as compared with the conventional case. As a result, it is possible to produce a solidified powder having improved mechanical properties as compared with the conventional one at a high yield.

Claims

The scope of the claims

1. A hypereutectic aluminum-mu-silicon alloy powder containing 12% to 50% by weight of silicon and 0.05% to 0.1% by weight of phosphorus.

2. The hypereutectic aluminum-silicon alloy powder according to claim 1, comprising at least 0.05% by weight of phosphorus and 0.05% by weight of phosphorus.

3. The hypereutectic aluminum-silicon-based alloy powder according to claim 1, comprising 0.02% by weight or more and 0.1% by weight or less of phosphorus.

4. The hypereutectic aluminum-silicon alloy powder according to claim 1, wherein the primary crystal silicon has a crystal grain size of 10 μm or less in the alloy powder.

5. Copper is 2.0% by weight or more and 3.0% by weight or less, magnesium is 0.5% by weight or more and 1.5% by weight or less, and manganese is 0.5% by weight or less.

Claim 1. Claim 2 containing not less than 2% by weight and not more than 0.8% by weight, not more than 0.05% by weight of phosphorus and not more than 0.05% by weight of phosphorus, and the balance being aluminum and unavoidable impurities. Hypereutectic aluminum-silicon alloy powder.

6. a step of preparing a melt of a hypereutectic aluminum-silicon alloy containing phosphorus;

Spraying the molten metal using air or an inert gas to rapidly cool and solidify the molten metal;

Of hypereutectic aluminum-silicon alloy powder with Construction method.

7. The step of preparing a molten aluminum-silicon alloy includes adding a primary crystal silicon refiner containing phosphorus to the molten aluminum-silicon alloy. 7. The method for producing an aluminum mini-silicon alloy powder according to item 6.

8. The step of preparing a molten aluminum-silicon alloy includes melting a solid of an aluminum-silicon alloy containing a primary crystal silicon refiner containing phosphorus in advance. 7. The method for producing a hypereutectic aluminum-silicon alloy powder according to claim 6.

9. The step of spraying and rapidly solidifying the molten metal is performed at a temperature 100 ° C. higher than the liquidus temperature of the aluminum silicate alloy. 7. The method for producing a hyper-eutectic aluminum alloy silicon-based alloy powder according to claim 6, comprising spraying the molten metal.

100. The step of spraying and rapidly solidifying the molten metal is carried out at a temperature of at least 100 ° C higher than the liquidus temperature of the aluminum alloy silicon-based alloy and at least 300 ° C or lower. The method for producing a hypereutectic aluminum silicon-based alloy powder according to claim 9, further comprising spraying the molten metal after holding the molten metal for about one minute.

1 1. A step of preparing a melt of hypereutectic aluminum-silicon alloy containing phosphorus. Preparing a hypereutectic aluminum-silicon alloy powder by spraying and rapidly solidifying the molten metal using air;

A method for producing a hypereutectic aluminum-silicon alloy powder comprising: a step of selecting the alloy powder having a particle size of 400 ^ m or less.

12. The hypereutectic aluminum silicon silicon according to claim 11, wherein the step of selecting the alloy powder includes selecting the alloy powder having a particle size of 200 μππ or less. Production method of base alloy powder.

13. The step of selecting the alloy powder includes selecting the alloy powder having a particle size of 100 Aim or less.

2. The method for producing hypereutectic aluminum silicon-based alloy powder according to item 1.

14. The hypereutectic aluminum silicon-based alloy powder according to claim 11, wherein the step of selecting the alloy powder includes selecting the alloy powder having a particle size of 50 m or less. Made of ia sword method o