JPH03253536A - Rapidly solidified aluminum powder alloy excellent in room temperature and high temperature strength - Google Patents

Abstract

PURPOSE:To obtain a rapidly solidified Al powder alloy showing high tensile strength from a room temp. to a high temp. of about 300 deg.C by specifying the content of Si and Fe in an Al-Si-Fe-Cu-Mg alloy. CONSTITUTION:This rapidly solidified Al powder alloy contains, by weight, 5 to 15% Fe, 1 to 8% Si, 1 to 8% Cu, 0.1 to 5% Mg and the balance Al. In this alloy, Fe forms intermetallic compounds with Al, which are finely dispersed at the time of atomizing to increase its high temp. strength. In the case of <5% Fe content, the effect is made insufficient, and even in the case of >15%, the effect is saturated, and furthermore, the intermetallic compounds are largely formed to deteriorate its forgeability. Si enters into solid soln. in Al to strengthen the matrix of Al and to increase its strength, and furthermore, it increases its modulus of elasticity and deteriorates its thermal expansion coefficient. As for the amt. of Si to be added, in the case of <1%, the effect of improving its strength is made insufficient, and in the case of >8%, brittle Al-Si-Fe intermetallic compounds are coarsened to deteriorate its strength.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to rapidly solidified aluminum powder alloys.

[Conventional technology] Aluminum alloys are lightweight and have excellent workability, so
It has been used as a structural material for aircraft and automobiles since ancient times. However, aluminum alloys have lower mechanical properties such as strength, rigidity, and heat resistance than steel, and also have a large coefficient of thermal expansion, which imposes restrictions on their use as structural materials.

Therefore, research on the composition, structure, heat treatment, etc. of aluminum alloys has been continued for many years in order to improve their strength, heat resistance, wear resistance, etc. However, in recent years, research on rapid solidification of aluminum alloys has been actively conducted, and knowledge has been obtained regarding the expansion of the solid solubility limit of alloying elements, the discovery of non-equilibrium crystal phases, and the refinement of crystal grains.
Development of powder metallurgy using rapidly solidified powder became active.

Rapidly solidified powder alloys with significantly improved high temperature strength, fatigue strength, corrosion resistance, etc. have been put into practical use.

For example, Al-Fe-based rapidly solidified powder containing a large amount of Fe has extremely excellent heat resistance, and Al-8% Fe alloys and those to which a third element is added are known. The invention disclosed in Japanese Patent Publication No. 63-9576 relates to the improvement of an Al-Fe-based rapidly solidified powder alloy, in which MO and Z are added as third elements to an Al-8% Fe alloy, and expensive He gas is used. A rapidly solidified powder alloy with excellent high-temperature strength was obtained without any

In addition, as a high-strength alloy at room temperature, A I-Z n-based X
7090 alloy is a typical example, and its composition is Al-
8% Zn-2, 5% Mg-1% C1M-1,5CO.

Aluminum has low rigidity compared to other metals, so
There is a demand for the development of high-rigidity alloys, and values of 100 Pa or more have been obtained for Al-3i-Fe alloys. Al-3i alloy has excellent wear resistance and has been known as silumin, but in Japanese Patent Application Laid-Open No. 125345/1982, a method is proposed in which hypereutectic Si and Fe are added as well as Cu and Mg. Accordingly, an AIAl-8i-Fe-Cu-alloy is disclosed which has improved abrasion resistance, sharpness, and room-temperature strength.

[Problems to be Solved by the Invention] Therefore, the above-mentioned Al-Fe alloy, AI-Z n alloy, and Al-8i-Fe alloy were prepared according to the methods described in the publications and literature, and were heated at room temperature. YoU300℃
The tensile strength was measured, and the obtained results are shown in FIGS. 1 and 2 as Comparative Examples 1 to 3.

The At-Fe alloy of Comparative Example 1 has higher strength than other alloys at a high temperature of 300°C, but its strength at room temperature is quite low. The strength at high temperatures is high, but the strength at high temperatures is very low.

The Al5i-Fe alloy of Comparative Example 3 has a strength comparable to that of the Al-Zn alloy of Comparative Example 2 at room temperature, but its strength at high temperatures is considerably lower than that of the Al-Fe alloy of Comparative Example 1.

However, in recent years, there has been a desire for the development of materials that can be used over a wide temperature range, that is, materials that have high strength from room temperature to high temperatures, for automobile parts, particularly engine parts. The present invention has been made in view of the above problems of rapidly solidified aluminum powder alloys, and an object of the present invention is to provide a rapidly solidified aluminum powder alloy that has high tensile strength from room temperature to high temperatures of about 300°C. .

[Means for Solving the Problems] The rapidly solidified aluminum powder alloy of the present invention, which has excellent strength at room temperature and high temperature, contains Fe; 5 to 15%, Si
; 1 to 8%, Cu: 1 to 8%, Mg: 0.1 to 5%, and the remainder consists of Al and inevitable impurities.

The aluminum powder alloy of the present invention is produced as a powder by rapid solidification. Methods for producing rapidly solidified aluminum powder include the gas atomization method, in which the molten aluminum alloy flowing out from the pores at the bottom of the container is pulverized by colliding with a high-pressure gas spray medium, and the rotating pot or rotary pot with many pores on the side. The powdering method using centrifugal force using a plate-shaped disk, the roll method in which molten metal particles are rapidly cooled with a cooling roll, etc. are used.

The cooling rate of the molten metal obtained by these rapidly solidified powder manufacturing methods is 102 to 10'/s. Therefore, the dendrite arm spacing, which indicates the degree of refinement of the solidified structure, is 1/100 or less of that of the melted material, and is generally extremely fine, 10 to 1 μm. Moreover, the supersaturated solid solubility of alloying elements increases significantly. O2, N2, water vapor, etc. are adsorbed on the surface of the rapidly solidified powder, and they separate from the powder at high temperatures to generate gas, so the powder must be degassed before use.

Furthermore, the surface of the rapidly solidified powder is covered with an aluminum oxide approximately 100 mm thick, which is chemically stable and cannot be removed by reduction, so sintering does not proceed and the powder does not undergo plastic deformation during solidification. Then, it is necessary to break the oxide film and bring the metal surfaces into contact with each other for diffusion bonding. Hot extrusion, friction extrusion, hot pressing, hot forging, HIP, etc. are used as methods for physically destroying the oxide film on the powder surface and solidifying the powder.

Next, the reason for limiting the composition range in the rapidly solidified aluminum powder alloy of the present invention will be explained.

Fe・5-15% Fe forms an intermetallic compound with AI, and this intermetallic compound is finely dispersed during atomization, and its dispersion strengthening increases the strength at high temperatures. Although the strength improves as the Fe content increases, the effect is insufficient if the Fe content is less than 5%. However, if the content exceeds 15%, not only the effect will be saturated, but also a large amount of intermetallic compounds will form, resulting in a decrease in forgeability, which is not preferable, so the upper limit was set at 152.

Si; 1 to 8% Si is dissolved in Al, not only strengthens the base of AI and increases the strength, but also increases the modulus of longitudinal elasticity and lowers the coefficient of thermal expansion. If the Si content is less than 1%, the effect of improving strength is insufficient. Furthermore, if the Si content exceeds 8%, Al
-3i-Fe-based brittle intermetallic compounds become coarse;
Strength decreases.

For this reason, the Si content was limited to 1 to 8%.

Curl~8% Cu is added to impart age hardenability.

Aging improves strength, especially at room temperature.

If the Cu content is less than 1%, the effect is not sufficient;
Exceeding this decreases toughness. For this reason, the Cu content was reduced to 1
It was limited to ~8%.

Mg; 0.1 to 5% M is an element added in order to coexist with Cu and impart age hardenability. When Mg is contained, the strength especially at room temperature is improved by aging. Its content is 0,1%
If it is less than 5%, the effect is insufficient, and if it exceeds 5%, the toughness decreases. Therefore, the Mg content was limited to 0.1 to 5%.

In addition, B, V are added to the aluminum rapidly solidified powder alloy of the present invention.
, Zr, MO, Cr or more at 0.1
When it is contained in a composition range of ~5%, it helps in dispersion strengthening of the A I-Fe intermetallic compound and further improves the room temperature and high temperature strength. When the content of these elements is less than 0.1%, the above-mentioned effects are insufficient, and when the content exceeds 5%, the toughness decreases. Therefore, when containing one or more of these elements, the total amount is 0.1 to 5
% is preferable.

[Example] Examples of the present invention will be explained together with comparative examples to clarify the effects of the present invention.

Alloying elements were blended with Al so that the chemical composition was as shown in Table 1. In Table 1, invention examples 1 to 6 contain V, B, and Zr.
This is an invention example in which one or more of Cr is added. Further, Comparative Example 1 is a conventional alloy corresponding to the Al-9i alloy, Comparative Example 2 is a conventional alloy corresponding to the Al-Zn alloy, and Comparative Example 3 is a conventional alloy corresponding to the Al-Zn alloy.
This is a conventional alloy that corresponds to the e-based alloy.

Comparative Examples 4 and 5 are comparative examples that contain V and the Fe content is outside the composition range of the present invention, and Comparative Examples 6 and 7 are comparative examples that contain V and the Si content is outside the composition range of the present invention. 0 Invention Examples 7 to 9 are invention examples that do not contain V, B, etc., and Comparative Examples 8 to 9 are comparative examples that do not contain V, B, etc. and have Si outside the composition range of the present invention.

(Left below) These compositions were heated in a high frequency heating furnace to prepare a molten aluminum alloy. Next, this molten aluminum base metal was heated to 1150°C and dropped from a nozzle with a nozzle diameter of 5 mm, and a gas pressure cuff was applied to the falling molten aluminum alloy.
A rapidly solidified powder alloy was obtained by blowing air at gf/c1G.

The obtained rapidly solidified aluminum powder alloy was sieved to 100 meshes or less, and this powder was preformed at room temperature using a mold at a molding pressure of 4 tons/c1. The obtained preform was preripened in nitrogen at 800 torr for 1 hour at 450°C, then inserted into an extrusion mold heated to 415°C, and extruded at an extrusion ratio of 12·l.

Among the obtained extruded materials, the alloy to which Cu and Mg were added was subjected to post-extrusion heat treatment (T6).

Although the heat treatment conditions differ depending on the composition, the solution temperature was selected at an appropriate temperature determined from the solidification curve, and the aging conditions were selected by determining the aging curve so that the hardness of each alloy would be the highest.

A test piece having a parallel portion diameter of 6.5 mm and a total length of 72 mm was prepared by machining from the extruded material prepared as described above, and was subjected to a tensile test. To explain the tensile test method, the tensile test at room temperature was conducted at a tensile rate of 1 stroke/min, and the number of samples tested was three. In the tensile test at 300°C, the test piece was heated in advance at 300°C for 100 hours, and this f&30
After holding for 15 minutes in a furnace heated to 0°C, the tensile rate was 1 a.
Tested at m/min. The test was conducted using three pieces.

The obtained results are the tensile strength at room temperature shown in Figure 1, the tensile strength at 300°C shown in Figure 2, and the Fe content and 300°C shown in Figure 3.
Fig. 4 is a diagram showing the relationship between the Si content and the tensile strength at normal temperature.

As is clear from Figures 1 and 2, Invention Examples 1 and 2 are superior to the conventional alloys of Comparative Examples 1 to 3 in both the tensile strength at room temperature and the tensile strength at 300°C. ,
It was confirmed that the alloy of the present invention has excellent tensile strength from room temperature to high temperature.

As can be seen from the diagram in Figure 3 showing the relationship between Fe content and tensile strength at 300°C, Comparative Example 4 contained only 1% Fe, so its tensile strength was extremely low. but,
In Invention Example 3 containing 5% Fe, the desired tensile strength is obtained, and the tensile strength increases linearly up to Invention Example 4 containing 15% Fe. However, in Comparative Example 5 containing 18% Fe, the improvement in tensile strength is saturated. This revealed that excellent tensile strength at 300° C. can be obtained in the Fe composition range of the present invention.

As can be seen from the diagram in Figure 4 showing the relationship between Si content and tensile strength at room temperature, Comparative Examples 6 and 8, which do not contain Si, and Comparative Examples 7 and 9, which contain 12% Si, have tensile strength. Although the tensile strength was extremely low, as the Si content increased, the tensile strength increased rapidly and reached a maximum value around 3 to 4% Si. As a result, in the Si composition range of the present invention,
It was confirmed that excellent tensile strength was obtained at room temperature.

As is clear from Figure 4, the series that contains V, B, etc. (indicated by ○ or △ in the figure) is different from the series that does not contain V, B, etc. (indicated by ○ or △ in the figure). It was found that superior room-temperature strength can be obtained than that of .).

[Effects of the Invention] As explained above, the aluminum rapidly solidified powder alloy of the present invention contains Fe, thereby finely dispersing the intermetallic compound with Al, increasing the strength at high temperatures through dispersion strengthening, and increasing the strength of Si. This product strengthens the matrix by solid solution, lowers the coefficient of thermal expansion, and improves the strength at room temperature.By adding Cu and M, the strength at room temperature is improved by age hardening. A rapidly solidified aluminum powder alloy with excellent high-temperature strength is obtained, and is extremely useful for reducing the weight of automobile parts.

[Brief explanation of drawings]

Fig. 1 is a bar graph showing the tensile strength at room temperature of the inventive example and comparative example, and Fig. 2 is a bar graph showing the tensile strength of the inventive example and comparative example at 300°C.
A bar graph showing the tensile strength at
A diagram showing the relationship with tensile strength at 00°C, Figure 4 shows the relationship between Si
It is a diagram showing the relationship between content and tensile strength at room temperature. Figure 1 Figure 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Invention 1 Invention 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Invention 1 Invention 2 Third
Figure 4

Claims (1)

[Claims] (1) In terms of weight ratio, Fe: 5 to 15%, Si: 1 to 8%,
A rapidly solidified aluminum powder alloy having excellent room temperature and high temperature strength, containing 1 to 8% Cu, 0.1 to 5% Mg, and the remainder consisting of Al and inevitable impurities.