JP3234379B2 - Heat resistant aluminum powder alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant and wear-resistant powder alloy obtained by joining heat-resistant Al alloy powder.

[0002]

2. Description of the Related Art Parts used in internal combustion engines such as automobiles and motorcycles, such as pistons, connecting rods and brake rotors, must be strong enough to withstand severe movements at high temperatures. On the other hand, in recent years, weight reduction of parts has been desired from the viewpoint of weight reduction of automobiles and the like and energy saving. For this reason, aluminum alloys have come to be used for parts requiring the high-temperature strength. As a heat-resistant aluminum alloy having such high-temperature strength, there is an Al-Si powder alloy containing about 13% by weight or more of Si. The powder alloy has fine primary crystal Si dispersed in the matrix, and is excellent in high temperature characteristics such as heat resistance. The Al-S
The i powder alloy uses the rapidly solidified powder alone or S
Hot plastic working is performed together with a dispersion strengthening material such as iC powder, and the powders are joined together and manufactured.

Further, as another heat-resistant aluminum alloy,
There is a powder alloy in which rapidly solidified powder of an Al-Fe alloy containing Fe in supersaturation is joined and integrated by hot plastic working. For example, JP-A-62-47448 discloses a hot extruded material of a heat-resistant aluminum alloy powder containing 10% by weight or more of Fe in supersaturation.

[0004]

However, since an oxide film is formed on the surface of the Al alloy powder, in order to integrate such heat-resistant Al alloy powder, the oxide film on the powder surface is divided and crushed to form a base. It is necessary to integrate them. For this reason, expensive high-output hot extruders and hot forging machines have conventionally been required. On the other hand, in the case of hot pressing,
Although it can be carried out with a relatively simple apparatus, there is a problem that the strength of the powder alloy is insufficient due to the bonding strength between the powders due to the oxide film on the surface of the powder. Further, the conventional Al alloy powder has a problem that the high-temperature strength is excellent but the wear resistance at high temperature is inferior.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and heat-resistant aluminum powder which is easily bonded and integrated at a high temperature, in other words, has a high compressive strength and further has excellent wear resistance at a high temperature. It is intended to provide an alloy.

[0006]

The heat-resistant aluminum powder alloy of the present invention comprises a heat-resistant aluminum alloy powder, a dispersion strengthening powder and N
The mixed powder of the i-powder is lower than the liquid phase onset temperature of the heat-resistant Al alloy
Heat-resistant aluminum that is joined and integrated by hot working
Powder alloy, the chemical composition of the dispersion strengthening powder
Is 30% to 50% by weight of Si, Ni, Cu, and Fe
Ni: 5 to 20%, Cu: 3 to 15%, Fe: 1 to 10
% Essentially within the range of 20-35%, with the balance
Part is a Si-Al-based alloy powder consisting essentially of Al.
The amount of heat-resistant Al alloy powder and Ni powder
Powder is 20 to 50 wt% with respect to the mixed powder.
And the dispersion strengthening powder is 5 to 80 w
t% (claim 1).

The heat-resistant aluminum powder alloy of the present invention
Means that the particle size of the heat-resistant Al alloy powder is 590 μm or less,
The particle size of powder for chemical conversion and Ni powder is 10 μm or less
(Claim 2).

[0008]

When the mixed powder of the heat-resistant Al alloy powder dispersion strengthening powder and the Ni powder is hot-worked at a temperature equal to or higher than the liquid phase starting temperature of the heat-resistant Al alloy powder, the molten portion of the heat-resistant Al alloy powder reacts with Ni, Since a Ni-Al intermetallic compound having a temperature equal to or higher than the eutectic temperature of the heat-resistant Al alloy is dispersed and generated in the molten portion, high-temperature strength is improved. For example, when Al-Si alloy powder is used as the heat-resistant Al alloy powder, the melt-solidified portion is made of Si and a Ni-Al intermetallic compound. In the case of using the Al-Fe alloy powder consists of Fe ₃ Al and Ni-Al intermetallic compound.
The melting point of the NiAl intermetallic compound is NiAl ₃ 85
5 ° C., 1135 ° C. for Ni ₂ Al ₃ , 1640 for NiAl
° C, Ni ₃ Al is 1397 ° C, and the eutectic point (570 ° C for Al-Si alloy, 640 ° C for Al-Fe alloy) of the original heat-resistant Al alloy disappears, so that a powder alloy excellent in heat resistance is obtained. Can be

On the other hand, in the present invention, a Si-Al alloy powder having the above specific composition is used as the dispersion strengthening powder. This S
Since the i-Al alloy powder is based on Si and Al, it is lightweight, has a high hardness (Hv 700 to 1000), has good heat and wear resistance, and has a Ni-Al heat resistant aluminide, High temperature strength is maintained. Further, the Cu-Al-based hard compound improves wear resistance, and elutes a very small amount of liquid phase stepwise over a wide range of about 530 to 750 ° C. For this reason, the bondability with the heat-resistant Al alloy is good, and the lubrication at high temperatures is exhibited.
The hot working temperature of the Si-Al alloy powder is preferably 6
The temperature is preferably set to 50 ° C. or lower. This is because the rapidly solidified structure is maintained at 650 ° C. or lower, but the structure changes at 650 ° C. or higher.

As described above, the hot working temperature is preferably set slightly higher than the liquid phase starting temperature. There is no effect if the temperature is too high, and the mold temperature should be low. Hereinafter, Si
The reasons for limiting the components of the Al-based alloy powder are shown below. The unit is% by weight. Si: 30 to 50% Si is mainly added for securing wear resistance and reducing the weight. If it is less than 30%, these effects, especially wear resistance, are insufficient, while if it exceeds 50%, the material becomes brittle.

Ni: 5 to 20% Ni is Ni- such as NiAl, Ni ₂ Al ₃ , NiAl ₃ or the like.
It is contained in order to generate an Al-based heat-resistant aluminide. In addition, it contributes to improvement of corrosion resistance. If it is less than 5%, the amount of heat-resistant aluminide will be insufficient, while if it exceeds 20%, the cost will increase and the melting point of the alloy will increase, making it difficult to melt. Cu: 3 to 15% Cu contributes to the improvement of corrosion resistance, Cu ₃ Al, CuA
It is contained in order to produce a hard aluminide having a solid lubricating action such as l ₂ . If it is less than 3%, the amount of aluminide is insufficient, while if it exceeds 15%, the amount of aluminide becomes excessive and the material becomes brittle.

Fe: 1 to 10% Fe, like Ni, has an effect of improving heat resistance and hot strength. If it is less than 1%, such an effect is insufficient, while if it exceeds 10%, a large amount of brittle Fe-Al intermetallic compound is generated, and the material becomes brittle. The Ni, Cu, and Fe components are 20 to 35% in total. If less than 20%, Ni-A
Since the total amount of l-type and Cu-Al-based heat-resistant aluminides is insufficient, excellent high-temperature strength and lubricating action cannot be expected. On the other hand, if it exceeds 35%, the specific gravity increases,
Weight reduction is impaired and dissolution becomes difficult.

In addition to the above essential alloy components, one or more of Zr, V, Ti, Ce, Nb, B and Co can be contained as an alloy component in a total amount of 1 to 5%. These components contribute to improvement in heat resistance. If it is less than 1%, the effect is almost negligible, while if it exceeds 5%, the melting point becomes too high and dissolution becomes difficult. In addition to the above alloy components, the balance is unavoidably mixed with impurities and Al, that is, substantially A
l. The rapidly solidified powder of the Si-Al alloy has a solid solution of the alloy element in a supersaturated state, and most of the high-content Si is crystallized as fine particles of about 0.5 to 3 μm. Al-Ni, C around the network
The structure becomes a structure in which a composite intermetallic compound of u and Fe is formed, and the matrix is strengthened.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Heat-resistant Al alloy powder and Si as raw materials of the present invention
-Al-based alloy powder is obtained by melting the raw material alloy by 50 to 2
It is dissolved at a high temperature of about 00 ° C., and is cooled to 10 ³ by an appropriate powder production means such as water or gas atomization method or rotary water flow method.
It is obtained by quenching at a cooling rate of about 〜１０10 ⁶ ° C./sec. By such rapid cooling, for example, in the case of an Al—Fe alloy, an Al alloy powder in which θ-FeAl ₃ is finely dispersed is obtained. The rotating water flow method is, as disclosed in Japanese Patent Application Laid-Open No. 17605/1992, to form a cooling water layer that swirls down on the inner peripheral surface of a cooling cylinder, and the molten metal flow is formed on the cooling water layer. Alternatively, there is provided a method in which droplets obtained by spraying the metal stream with an inert gas are supplied, divided by a rotating cooling liquid layer, and rapidly solidified to obtain metal powder. According to this production method, a cooling rate of 10 ⁵ ° C / sec or more can be easily obtained even with relatively large particles having an average particle size of 200 µm.

Suitable heat-resistant Al alloy powders include Al-Si alloy powder having a Si content of about 13 to 30% by weight and Al-Fe alloy powder disclosed in the above-mentioned JP-A-62-47448. High-temperature, high-strength Al alloy powder can be used. Preferably, it has a tensile strength of 20 kgf / mm ² or more at 300 ° C. after being integrated by hot working. Such a heat-resistant Al alloy essentially contains, in addition to the above alloy, one or more transition metals of Fe, Mn, Ni, and Cr in a total amount of 15 to 25 wt%, and if necessary, the essential alloy component. In addition to Mo, V,
A material containing one or more of Ti, Zr, and Co in a total amount of 3 wt% or less and the balance substantially consisting of Al can be exemplified. In addition, in the Al alloy powder containing Fe,
After hot working, a temperature range in which a liquid phase is not formed (for example, in the case of Al-Fe alloy powder containing Fe of 38 wt% or less, 50
0 to 630 ° C.) to obtain Al
-Ni-Fe intermetallic compound can be generated, and a heat and wear resistant aluminum powder alloy can be obtained.

The compounding amount of the heat-resistant Al alloy powder and the Ni powder is such that the latter powder is 20 to 50 wt% based on the mixed powder.
Good degree. If it is less than 20% by weight, the effect of promoting the bonding of the Ni powder is insufficient, while if it exceeds 50% by weight, the reduction in weight is impaired. Although the particle size of the powder is not particularly limited, usually, the heat-resistant Al alloy powder is 590 μm or less, and the Ni powder is 1 μm or less.
Those having a size of 0 μm or less are used. To improve wear resistance,
In the present invention, a Si-Al alloy powder is added to the mixed powder as a dispersion strengthening powder. The particle size of this powder is preferably 10 μm or less in order to ensure uniformity of the material, and its blending amount is preferably about 5 to 80% by weight based on the mixed powder after addition. If it is less than 5 wt%, the reinforcing effect is small, while 80 w
If it exceeds t%, the material becomes brittle.

Appropriate hot working means such as hot extrusion, hot forging, hot isostatic pressing, and hot uniaxial compression can be applied as the means for joining and integrating the mixed powder. In the present invention, an Al-Ni phase is generated by the action of the Ni powder, and the powders are joined to each other via this phase. Therefore, the powder can be easily formed by uniaxial compression molding. In addition, when the material is subjected to hot working, it may be preliminarily formed by cold compression in consideration of handleability of the raw material powder. Next, specific examples and comparative examples of the present invention are shown in Table 1 below.

[0018]

[Table 1]

<Examples of the Present Invention (Sample No. 2 in Table 1)> (1) Al-Si alloy powder having an average particle diameter of 200 μm (27
% Si, balance Al), Ni powder having an average particle diameter of 5 μm, Si-Al alloy powder for dispersion strengthening having an average particle diameter of 50 μm (44
% Si, 33% Al, 4% Fe, 7% Cu, 12% N
i) was prepared and uniformly mixed according to the formulation shown in Example No. 2 of Table 1 to prepare a mixed powder. All units are% by weight. (2) The mixed powder was mixed at the molding temperature shown in the table at 700 MPa.
a) Uniaxial compression (hot pressing) was performed to obtain a molded product having an outer diameter of 64 mm. The relative density of this compact was 99.9%. <Comparative Example (Sample No. 1 in Table 1)> The difference between Comparative Example No. 1 and Example No. 2 of the present invention is that Si- Al alloy powder is not used.
Only the difference between the contents of the l-Si powder and the Ni powder is shown. <Comparative Example (Sample No. 3 in Table 1)> The difference between Comparative Example No. 3 and Example No. 2 of the present invention is that No. 3 is Al-Si in Example No. 2.
It shows the one using only the powder. (3) Test specimens were taken from these compacts, and
The compressive strength at 00 ° C. was measured. Table 1 shows the results. From the above Table 1, it can be seen that Example No. 2 of the present invention and Comparative Example
It can be seen that No. 1 has significantly improved high-temperature compressive strength compared to Comparative Example No. 3. (4) As a result of EPMA analysis using the compacts of Example No. 2 and Comparative Example No. 1 of the present invention after hot pressing, N
i ₂ Al ₃ was identified. Furthermore, 570 ° C.
After holding for 2 hours at, a heat treatment for furnace cooling was performed, and EPMA analysis was performed using the obtained sample. In addition to Ni ₂ Al ₃ , NiAl ₃ was identified. On the other hand, Ni was not recognized. From this, it is presumed that the Ni powder portion was replaced with Ni ₂ Al ₃ and NiAl ₃ .

Incidentally, Comparative Example No. 1 in Table 1 above was used.
In comparison with the compressive strength of Example No. 2 of the present invention at 400 ° C., which is a high temperature, the former Comparative Example No. 1 is slightly higher in numerical value, but slightly higher. Therefore, as long as the two are compared, the effect of the dispersion strengthening powder (Si-Al-based alloy powder) used in the examples of the present invention is not clear. Therefore, the present inventors have developed a method of evaluating the wear resistance at high temperatures by measuring the surface roughness Ra. As a result of the following experiment for measuring μm, data as shown in Table 2 were obtained.

[0021]

[Table 2]

From Table 1 above, Example No. 2 of the present invention is different from Comparative Example No. 1 in terms of high-temperature compressive strength by mixing a Si—Al alloy powder having a specific composition as a dispersion strengthening powder. Although the difference is small, high temperature abrasion resistance was improved as compared with the latter.

[0023]

As described above, in the heat-resistant aluminum powder alloy of the present invention, the mixed powder of the heat-resistant Al alloy powder and the Ni powder is joined and integrated by hot working at a temperature equal to or higher than the liquid phase starting temperature of the heat-resistant Al alloy. Therefore, the original heat-resistant Al formed by the reaction between the molten portion of the heat-resistant Al alloy powder and Ni
High temperature strength and heat resistance are improved by a Ni-Al intermetallic compound having a melting point equal to or higher than the eutectic temperature of the alloy. At this time, in the present invention, in particular, by mixing a Si—Al alloy powder having a specific composition as the dispersion strengthening powder with the mixed powder, the heat and wear resistance can be further improved.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuo Nagata 1-1-1 Hama, Amagasaki City, Hyogo Prefecture Inside Kubota Technology Development Laboratory Co., Ltd. (56) References JP-A-1-92329 (JP, A) JP JP-A-1-279701 (JP, A) JP-A-55-19476 (JP, A) JP-A-61-124549 (JP, A) JP-A-63-277728 (JP, A)

Claims (2)

(57) [Claims] 1. A heat-resistant Al alloy powder, a dispersion strengthening powder, and N
The mixed powder of the i-powder is lower than the liquid phase onset temperature of the heat-resistant Al alloy
Heat-resistant aluminum that is joined and integrated by hot working
Powder alloy, wherein the chemical composition of the dispersion strengthening powder is 30 wt% Si:
５０50%, Ni: Cu, Fe is Ni: 5-20%, C
u: 3 to 15%, Fe: 1 to 10%, total: 2
0-35%, with the balance being substantially from Al
Si-Al alloy powder and heat-resistant Al alloy powder
Powder and the amount of Ni powder are such that the latter powder is
And 20 to 50% by weight, and the powder for dispersion strengthening is
It is characterized in that it is 5 to 80 wt% with respect to the mixed powder.
Heat-resistant aluminum powder alloy. 2. The heat-resistant Al alloy powder has a particle size of 590 μm or less.
Below, the particle size of the dispersion strengthening powder and the Ni powder was 10
The heat-resistant aluminum powder according to claim 1, which has a size of not more than μm.
Powder alloy.