JPS63145725A - Heat resistant aluminum alloy member having high strength and ductility - Google Patents

Abstract

PURPOSE:To improve the strength and ductility of an Al alloy member at high temp. as well as to provide superior heat resistance, by hot forming Al alloy powder contg. a specified amt. of Mg produced by mechanical alloying. CONSTITUTION:Dispersion strengthening Al alloy powder contg. 0.3-2.0wt% Mg or further contg. one or more kinds of hard metals or ceramics is produced by mechanical alloying. The alloy powder is hot formed at least once at <=500 deg.C optionally after preforming to obtain an Al alloy member having superior heat resistance which can not be provided in case of a conventional Al alloy and also having superior strength and ductility at high temp.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides heat-resistant, high-strength, The present invention relates to a highly ductile aluminum alloy member.

[Conventional technology]

With recent rapid advances in technology in various fields, there is a strong demand for the development of new materials with even higher functionality. Conventionally, aluminum alloys have been widely used in various fields because they are lightweight and have high strength. However, since the melting point of aluminum alloy is 660'C (absolute temperature 933 K) at its highest, it is generally half that (193 °C, absolute temperature 466 °C).
) It softens significantly at temperatures above ). Therefore, aluminum alloys could not be used as strong summer members at high temperatures. Titanium is well known as a lightweight, heat-resistant metal.

However, the specific gravity of titanium is about 4.5, which is more than 50% larger than that of aluminum alloy. Therefore, there is a strong desire to develop a heat-resistant, high-strength aluminum alloy member that can be used up to a high temperature of about 400°C.

Recently, the following powder metallurgy method has been attracting attention as a new method for manufacturing aluminum alloy members to meet such demands.

Powder metallurgy method using fi+ rapidly solidified aluminum alloy powder.

This method is an alloy of aluminum and transition metal elements that could not be produced using conventional melt casting methods.
In this method, rapidly solidified powder of At--Fe alloy, etc.) is hot-formed to form an aluminum alloy member. According to this method, it is possible to manufacture an aluminum alloy member having significantly superior heat resistance compared to the conventional method.

(2) Powder metallurgy using mechanically alloyed powders.

In this method, several types of raw material powders to be alloyed are placed in a high-energy stirring mill and mixed.

This is a method in which pulverization and pressure welding are repeated, and the thus mechanically alloyed or composited powder is formed into an aluminum alloy member using powder metallurgy means. For example, when aluminum powder and magnesium powder of 4wt/% are mechanically alloyed using an attritor (high energy ball mill), the magnesium powder is not dispersed in the aluminum and is #! Alloys that form a single phase in complete solid solution, i.e.
Alloying in the true sense is achieved.

Another effective method for mechanical alloying is known to process aluminum powder or prealloyed aluminum alloy powder and hard metal powder or ceramic powder in a high energy ball mill. According to this method, a mechanically alloyed powder in which hard particles of hard metal powder or ceramic powder are uniformly and finely dispersed can be obtained. In this case, the hard particles and the aluminum powder or aluminum alloy powder do not necessarily undergo a metallurgical reaction. Therefore, its state is significantly different from that of alloyed powder obtained by ordinary melting and casting methods, and it often exhibits excellent high-temperature strength as a composite-strengthened or dispersion-strengthened alloy.

Such aluminum-based mechanical alloys are attracting attention as a new type of alloy.

The simplest method for mechanical alloying is to feed aluminum powder or aluminum alloy powder alone into a high-energy ball mill. This method also provides a sufficiently strong powder. The first reason why powder with such high strength is obtained is that aluminum powder or aluminum alloy powder undergoes significant work hardening when repeatedly subjected to crushing and pressure welding.

The second reason is that aluminum reacts with oxygen and charcoal contained in the atmosphere or auxiliaries to produce aluminum oxide and aluminum carbide, and these products are finely divided. It is thought that this is to disperse as hard particles to bring about dispersion reinforcement and to prevent the work-hardened state from returning.

In the present invention, mechanical alloying generally refers to a method for producing reinforced powder using high-energy poles, regardless of whether there is one type of raw material powder or multiple types of raw material powder.

The applications of mechanical alloying are diverse, and mechanical alloying of aluminum-based alloys is particularly useful as a means of imparting excellent heat resistance. However, even in aluminum alloy members manufactured by a powder metallurgy method using mechanically alloyed powder, all properties are not sufficiently satisfactory for practical use.

In particular, a serious problem with aluminum alloy parts manufactured by powder metallurgy using mechanically alloyed powder is high temperatures (the high temperatures that are problematic for aluminum-based alloys are approximately 200°C to 400°C). ), the strength is high, but the ductility is extremely low.

Typical aluminum alloys exhibit a significant decrease in strength at high temperatures, while their ductility increases.

In addition, heat-resistant aluminum alloys using rapidly solidified powder (
For example, At-Fe alloy members exhibit high strength and relatively low ductility at room temperature, but as the temperature increases, the strength gradually decreases while the ductility gradually increases.

In contrast, aluminum alloy parts manufactured by powder metallurgy using mechanically alloyed powders exhibit high strength and moderate ductility at room temperature, but their strength gradually decreases as the temperature increases. Furthermore, ductility is also reduced.

In other words, although aluminum alloy parts manufactured by powder metallurgy using mechanically alloyed powder have high strength at high temperatures, they have low ductility at high temperatures, making it difficult to use them in a wide range of applications. In between.

Therefore, it is an object of the present invention to provide a dispersion-strengthened aluminum-based alloyed powder prepared by a mechanical alloying method, produced by a powder metallurgy method,
The object of the present invention is to provide an aluminum alloy member having excellent strength and sufficient ductility at high temperatures of °C.

[Means for solving problems]

The present invention provides an aluminum-based mechanically alloyed powder containing at least magnesium, or at least magnesium, one or more hard metals and 1&'
E or at least one of two or more types of ceramics
aluminum-based mechanically alloyed powder containing ai,
In an aluminum alloy member obtained as it is or by preforming and hot forming at least once at a temperature of 500° C. or less, the magnesium content in the aluminum-based mechanically alloyed powder is 0.3. ~
It is characterized by being 2.0 important.

The present inventors have developed an aluminum alloy member manufactured by a powder metallurgy method using aluminum-based mechanically alloyed powder, and which has both practically sufficient strength and ductility even at high temperatures. We conducted extensive research to develop it.

As a result, it was found that if an aluminum-based mechanically alloyed powder containing magnesium within a certain range was used as a raw material, an aluminum alloy member with excellent strength and ductility at high temperatures could be obtained.

This invention has been made based on the above findings.

Next, the present invention will be explained in detail.

(1) Aluminum powder and aluminum alloy powder.

The first reason why powder with excellent heat resistance can be obtained through mechanical alloying of aluminum bases is that it prevents significant work hardening due to stirring in a high-energy goal mill and seizures in the atmosphere and during stirring. It consists in a fine dispersion of particles such as aluminum oxide and aluminum carbide produced by the reaction of aluminum with oxygen and carbon contained in an auxiliary agent (for example, a small amount of methanol) for the production of aluminum.

Therefore, the raw material powder used for mechanical alloying of aluminum groups may be pure aluminum powder, prealloyed aluminum alloy powder, or a mixture of several types of these powders. The types of these raw material powders and their mixing ratios are determined in order to achieve the properties required for the final aluminum alloy member and to pursue better economic efficiency.

(2) Magnesium powder.

The reason why magnesium is included in the aluminum-based mechanically alloyed powder is to improve ductility at high temperatures.

The high temperature ductility of the final unexploded aluminum alloy component is essentially determined by the magnesium content in the aluminum-based mechanically alloyed powder. The method for adding magnesium may be to include magnesium in advance in the aluminum alloy, to add and mix magnesium as a single powder, or to use a combination of these.

Therefore, economy is the criterion for selecting the magnesium addition method. That is, for example, if pure aluminum powder is suitable as a raw material, it is more economical to incorporate magnesium into the aluminum alloy in advance, or to separately mix the magnesium powder with soybean.

Next, the magnesium content in the aluminum-based mechanically alloyed powder will be explained.

When magnesium is added to aluminum, the strength of the aluminum alloy member increases with almost no decrease in ductility.

However, the effect of magnesium content fQi on the strength and ductility at room and high temperatures of an aluminum alloy member formed by powder metallurgy using an aluminum-based mechanically alloyed powder is quite complex.

In other words, in terms of strength, as the magnesium content increases, the strength at room temperature increases, but on the other hand, the strength at high temperatures rather gradually decreases.In particular, when the magnesium content exceeds a certain amount, the strength at high temperatures increases. strength is significantly reduced.

Next, in terms of ductility, as mentioned above, aluminum alloy parts formed by powder metallurgy using aluminum-based mechanically alloyed powders that do not contain magnesium have moderate ductility (e.g. 10 in tensile elongation
%), but on the other hand, the higher the temperature, the lower the ductility.

□On the other hand, when magnesium is added, the decrease in ductility is suppressed up to a certain temperature. In other words, as the magnesium content increases, the temperature range in which the decrease in ductility is suppressed is expanded to a much higher temperature side, and furthermore, when the magnesium content increases and exceeds a certain amount, the ductility at high temperatures increases significantly. .

The absolute value of ductility (tensile elongation, etc.) varies depending on the type of raw aluminum alloy, the type, size and volume ratio of hard particles, mechanical alloying conditions, hot forming conditions, etc. The effect of magnesium content on increasing ductility is basically the same.

That is, if the magnesium content in the aluminum-based mechanically alloyed powder is less than 0.3% by weight, the ductility at high temperatures will be insufficient.On the other hand, if it exceeds 2.0% by weight, the ductility at high temperatures will be insufficient. Although the size increases, the strength decreases significantly and practicality is lost.

For the above reasons, the magnesium content in the aluminum-based mechanically alloyed powder should be within the range of 0.3% by weight to 2.0% by weight.

(31 Hard metal and ceramics The first reason for including hard metal powder (hard metal particles) or ceramic powder (ceramic particles) as a raw material for aluminum-based mechanically alloyed powder is mechanical alloying. This is because it is effective in promoting work hardening and suppressing recovery from work hardening.Furthermore, the second reason is that the properties of the final aluminum alloy member, such as increased strength and rigidity, increased wear resistance, This is because they are effective in reducing the coefficient of thermal expansion and the like.

The type, size and amount of the hard metal powder and ceramic powder particles are selected depending on the properties required of the final aluminum alloy member.

As hard metal powders, for example powders of molybdenum, tungsten, iron, nickel, cobalt, manganese, chromium, panasium and titanium can be used.

As the ceramic powder, for example, powders such as 5iC1 alumina and sorconia can be used.

In general, the larger the volume fraction of hard metal particles or ceramic particles in the aluminum alloy member and the larger the size of the particles, the more difficult it is to hot form the aluminum-based mechanically alloyed powder. , the ductility of the final aluminum alloy member decreases.

Therefore, the volume fraction of the hard metal particles or ceramic particles is preferably 30% or less. Furthermore, it is preferable that the hard metal particles or ceramic particles hardly react with the aluminum element or the alloying element in the aluminum alloy. However, the reaction is limited to the interface between the aluminum base and hard metal particles or ceramic particles.
This is because it increases the wettability between the ground and particles and creates a favorable composite state. On the other hand, when the reaction product forms a large phase, the handling properties of the aluminum alloy member are generally reduced in many cases.

As described above in fil~(3), the aluminum-based mechanically alloyed powder used in the present invention is an aluminum-based mechanically alloyed powder containing at least magnesium, or at least one or two types of aluminum-based mechanically alloyed powder containing at least magnesium.
Hard metals and IP over @! An aluminum-based mechanically alloyed powder containing at least one glaze of one or more ceramics should be used.

The above-mentioned aluminum-based mechanically alloyed powder containing at least magnesium is one mechanically alloyed using any one of the following materials (1) to (2) as raw materials.

■At least 1f of magnesium powder, aluminum powder, and aluminum alloy powder! 1II0 ■ Aluminum-magnesium alloy powder.

(2) At least one of aluminum-magnesium alloy powder, aluminum powder, and aluminum alloy powder.

The aluminum-based mechanically alloyed powder containing at least one of the above-mentioned magnesium, one or more hard metals, and one or more ceramics includes the following Use one that is mechanically alloyed using one of them as a raw material.

■ Magnesium powder, at least one of aluminum powder and aluminum alloy powder, and
Seed or 2 f! Hard metal powder of II or higher and l&or 2a! At least one of the above ceramic powders.

(2) At least one of aluminum-magnesium alloy powder, one or more hard metal powders, and one or more ceramic powders.

(2) Aluminum-magnesium alloy powder, at least one of aluminum powder and aluminum alloy powder, and at least one of one or more hard metal powders and one or more ceramic powders.

As explained above, the raw materials for the aluminum-based mechanically alloyed powder used in the present invention include aluminum powder, aluminum alloy powder, magnesium powder, aluminum-magnesium alloy powder, hard metal powder, and ceramic powder. So you can use
This is extremely advantageous in terms of raw material selection.

(4) Hot-forming Hot-forming is essential in order to obtain an aluminum alloy member that is dense and has good mechanical properties from an aluminum-based mechanically alloyed powder. The reason is that the surface of the aluminum-based mechanically alloyed powder is covered with an oxide film, so it is necessary to apply sufficient plastic deformation to break this film and achieve bonding between each metal. .

In order to apply cold plastic deformation, an excessive forming force is required, so cold plastic deformation is not appropriate.

As the hot forming method, a method capable of imparting sufficient plastic deformation, such as extrusion or forging, should be used.

However, if the hot forming temperature exceeds 500℃, the recovery of the highly processed structure obtained by mechanical alloying will proceed, and the reaction between the 9 dispersed particles and the aluminum base will proceed, producing harmful reaction products. It's not appropriate.

Therefore, the hot forming temperature should be 500°C or less.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 Pure aluminum powder of -36 to +250 mesh was added to -
Magnesium powder of 20 to +50 mesh was mixed at a ratio within the scope of the present invention and outside the scope of the present invention, and each was charged into an attritor (high energy goal mill) and mechanically alloyed under the same conditions. An aluminum-based mechanically alloyed powder was prepared.

Each of the aluminum-based mechanically alloyed powders thus obtained was cold-pressed to prepare a green compact. Next, the green compact is hot-pressed at a temperature of 400°C to form a billet, and the resulting billet is hot-extruded at a temperature of 450°C to form a round bar alloy member of the present invention. Specimen N
11L1 to 3, and comparative specimen parts 1 to 4 in the shape of round bar alloy members were prepared. Table 1 shows the magnesium content of specimens Flies 1 to 3 of the present invention and comparative specimens M1 to M4.

It should be noted that the mechanically alloyed aluminum-based mechanically alloyed powder was analyzed to contain 0.2% by weight or less of iron and silica as major impurities. The extrusion ratio for hot extrusion is 20″′
There is C.

Each specimen thus prepared was subjected to a tensile test at room temperature and high temperature (200 to 300°C), and the tensile strength and elongation (ductility) of each specimen were measured. The measurement results are also shown in Table 1.

As shown in Table 1, comparative specimens Nα1 and 2, in which the magnesium content in the aluminum-based mechanically alloyed powder is less than the range of the present invention, have excellent tensile strength at room temperature and high temperature. The higher the temperature, the lower the elongation, and the reliability as a heat-resistant member is insufficient.

Comparative specimens Na 3 and 4, whose magnesium content in aluminum-based mechanically alloyed powders exceeds the scope of the present invention, exhibit high tensile strength and moderate elongation at room temperature; However, the tensile strength at high temperatures decreases significantly, making it unsuitable for use as a heat-resistant member.

On the other hand, the specimen Nll~3 of the present invention was heated to 300°C.
The tensile strength at the temperature of
It shows an elongation of 1096 or more even at temperatures of ℃, and has excellent heat resistance.
It exhibits excellent characteristics as a high-strength, high-ductility material.

Example 2 A JIS or American Aluminum Association (AA) standard alloy containing ρ and magnesium within the range of the present invention, and having a second
3004.5005 and 2618, which have the chemical composition shown in the table, and do not contain magnesium.
A total of four types of aluminum alloy powders of 3003 having the chemical composition shown in Table 2 were prepared into powders by air atomization. In addition, all grain summers are 1100
It's Metush.

The four types of aluminum alloy powder prepared as described above were
Attritor (high energy%'-&-lumil) respectively
and mechanically alloyed under the same conditions to prepare an aluminum-based mechanically alloyed powder.

Furthermore, mechanical alloying was also performed on a separately prepared mixed powder obtained by mixing the above-mentioned 3003 aluminum alloy powder with magnesium powder in a content within the range of the present invention. The magnesium content in the obtained aluminum-based mechanically alloyed powder was measured at 1.261 points.

Each of the aluminum-based mechanically alloyed powders thus obtained was cold-pressed to prepare a green compact. Next, the green compact is hot-pressed at a temperature of 400°C to form a billet, and the resulting billet is hot-extruded at a temperature of 450°C to form a round bar alloy member of the present invention. Specimen N
a4, 5 and 7, comparison specimen Na in the form of a round bar alloy member
Round bar alloy members No. 5 and No. 2618 were made from vQ.

Since the aluminum-based mechanically alloyed powder used as the raw material for 2618t is a heat-treatable alloy, the round bar alloy member of 2618 was further solution-treated at 520°C for 1 hour, then water-quenched, and then heated to 200°C. A test specimen N116 of the present invention in the form of a round bar alloy member was prepared by subjecting it to heat refining (T6 heat refining) consisting of artificial aging at a temperature of 8 hours at a temperature of .degree.

Each specimen thus prepared was subjected to a tensile test at room temperature and high temperature (200 to 300°C), and the tensile strength and elongation (ductility) of each specimen were measured. The measurement results are shown in Table 3.

As shown in Table 3, the comparative specimen Na5 exhibited a decrease in elongation at high temperatures.

On the other hand, the specimens Na4, 5 and 7 of the present invention were
All exhibited excellent tensile strength at room temperature and high temperature, and also exhibited high elongation at room temperature and high temperature.

Specimen 6 of the present invention made from 2618 alloy powder showed high elongation at room temperature and high temperature, and exhibited excellent tensile strength at room temperature and 200°C.

Example 3 One or more of the aluminum powder bed, aluminum alloy powder, and magnesium powder were further mixed with various hard metal powders or ceramic powders, and the magnesium-containing powder of the present invention was mixed with an attritor. Aluminum-based mechanically alloyed powders within the scope or outside the scope of the present invention were prepared.

Each of the aluminum-based mechanically alloyed powders thus obtained was cold-pressed to prepare a green compact. Next, the green compact is hot-pressed at a temperature of 400°C to form a billet, and the resulting billet is hot-extruded at a temperature of 450°C to produce the present invention in the form of a round bar alloy member. Sample height 8
and 9, and comparative specimen Nα in the form of a round bar alloy member.
6 and 7 were prepared.

Table 4 shows the types of raw material powders for specimens 8 and 9 of the present invention and comparative specimens 6 and 7, respectively.
Content, average diameter, and analytical values of magnesium content in mechanically alloyed powder are shown.

...The extrusion ratio of hot extrusion is 20.

・Tensile tests were conducted on each specimen thus prepared at room temperature and high temperature (200 to 300°C), and the tensile strength and elongation (ductility) of each specimen were measured. are also shown in Table 4.

As shown in Table 4, the elongation of specific soft specimens Ntx 6 and 7 whose magnesium content was less than the range of the present invention decreased as the temperature increased.

On the other hand, the specimen Nα of the present invention in which the magnesium content was within the range of the present invention and also contained molybdenum
8 shows excellent tensile strength at room temperature and high temperature,
Furthermore, it showed high tensile elongation at room temperature and high temperature. Molybdenum contained in the specimen Nt18 of the present invention is a metal that is hard and does not easily react with aluminum. However, by mechanically alloying a relatively succulent mixture of fine molybdenum particles, it is possible to considerably improve the heat resistance, strength, and ductility of the aluminum-based vitremechanically alloyed powder and the final aluminum alloy member. can.

Magnesium-containing needles are within the scope of the present invention and Si
The specimen t4α9 of the present invention containing C exhibited a tensile strength that deteriorated at room temperature and high temperature.

In this way, when 10 to 30 bi% of SiC fine powder is mixed and mechanical alloying 2 is performed, S
A composite powder in which iC particles are uniformly dispersed is obtained. Therefore, the final alloy member obtained from this powder has not only heat resistance but also wear resistance, low coefficient of thermal expansion, and ductility at high temperatures that are significantly superior to conventional aluminum alloys.

As described above, the aluminum alloy member of the present invention using hard metal powder or ceramic powder as raw material powder has many practical uses.

〔Effect of the invention〕

As explained above, the aluminum alloy member of the present invention has heat resistance that cannot be obtained with conventional aluminum alloys, and has excellent strength and ductility especially at high temperatures, so it can be used in a wide range of applications. Many excellent industrial effects are brought about, such as the possibility of

Claims (8)

[Claims] (1) In an aluminum alloy member obtained by hot-forming an aluminum-based mechanically alloyed powder containing at least magnesium at a temperature of 500°C or less, either as it is or after being preformed, at least once. , a heat-resistant, high-strength, high-ductility aluminum alloy member, characterized in that the magnesium content in the aluminum-based mechanically alloyed powder is 0.3 to 2.0% by weight. (2) The aluminum-based mechanically alloyed powder is obtained by mechanically alloying magnesium powder as a raw material with at least one of aluminum powder and aluminum alloy powder. No. (
The heat-resistant, high-strength, high-ductility aluminum alloy member described in item 1). (3) The aluminum-based mechanically alloyed powder is obtained by mechanically alloying aluminum-magnesium alloy powder as a raw material.
The heat-resistant, high-strength, high-ductility aluminum alloy member described in . (4) The aluminum-based mechanically alloyed powder is characterized in that it is formed by mechanically alloying aluminum-magnesium alloy powder as a raw material with at least one of aluminum powder and aluminum alloy powder.
A heat-resistant, high-strength, high-ductility aluminum alloy member according to claim (1). (5) Aluminum-based mechanically alloyed powder containing at least magnesium and at least one of one or more hard metals and one or more ceramics, either as is or in advance. In an aluminum alloy member obtained by forming and hot forming at least once at a temperature of 500° C. or less, the magnesium content in the aluminum-based mechanically alloyed powder is 0.3 to 2.0. A heat-resistant, high-strength, high-ductility aluminum alloy member, characterized by weight%. (6) The aluminum-based mechanically alloyed powder contains magnesium powder as a raw material, at least one of aluminum powder and aluminum alloy powder, one or more hard metal powders, and one or more hard metal powders. The heat-resistant, high-strength, high-ductility aluminum alloy member according to claim (5), which is formed by mechanically alloying at least one of two or more types of ceramic powders. (7) The aluminum-based mechanically alloyed powder contains aluminum-magnesium alloy powder as a raw material, at least one of one or more hard metal powders and one or more ceramic powders. Claim No. 5 (5) is characterized in that it is formed by mechanically alloying
) A heat-resistant, high-strength, high-ductility aluminum alloy member. (8) The aluminum-based mechanically alloyed powder contains aluminum-magnesium alloy powder as a raw material, at least one of aluminum powder and aluminum alloy powder, and one or more hard metal powders and The heat-resistant, high-strength material according to claim (5), which is formed by mechanically alloying at least one of one or more types of ceramic powders;
Highly ductile aluminum alloy member.