JPH02194102A - Al base alloy powder for sintering - Google Patents

Abstract

PURPOSE:To obtain Al base alloy powder having excellent formability after extrusion-working and improving strength at room temp. and high temp. with heat treatment after forming by using the Al base alloy powder of the specific composition. CONSTITUTION:The composition of the Al base alloy powder is specified so as to contain 2 - 5wt.% Cr and 1 - 2.8% Zr as essential components and 0.5 - 5% the total content of one or two elements selected from 0.5 - 5% Cu and 0.5 - 5% Ni and the balance of Al and inevitable impurities. In these elements, Cr and Zr are made to solid solution under condition of supersaturation in Al matrix at the time of rapidly cooling and solidifying, but precipitated in the matrix at the time of solid-formation in hot-state and heat treatment after that and have action promoting the strength of the sintered body at the room temp. and the high temp. Further, Cu and Ni have action promoting age- hardening with Cr and Zr and increases the peak hardness after age-hardening. Then, this sintered body is most suitable to use for material having complicate shape and needing high strength at the high temp. and the room temp., such as various kinds of engine parts including connecting rod, outer shell of airplane.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention serves as a raw material for Al-based alloy powder sintered bodies that are widely used in various industrial machinery fields such as automobiles, aircraft, railway vehicles, and ships. This invention relates to Al-based metal powder for sintering.

[Prior art] In recent years, as a new technology of Al powder metallurgy, a rapid solidification method has been applied to obtain Al-based alloy powder in which Al contains various transition elements, and the Al-based alloy powder has been used to form a sintered body. Many technologies have been developed to produce sintered bodies with high hot strength by molding.

The above technology uses Al-Fe and Al-Cr whose compositions cannot be obtained in an equilibrium state when rapidly solidified powder is used.

It is an application of the fact that alloys such as Al-Zr and Al-5t can be manufactured, and the size of crystal grains and fine mixture can be adjusted, and it is heat resistant.

This makes it possible to obtain a new material with excellent wear resistance and fatigue strength.

For example, JP-A-59-43802, JP-A-60-23
No. 4936, No. 60-248860, No. 61
-49551 publication, 61-96051 publication, 5
Many techniques are disclosed in Japanese Patent No. 1-130451, and similar techniques are also disclosed in US Pat. No. 4,464,199.

All of the techniques found in the above documents contain approximately 8 to 12% Fe, as well as rare earth elements such as Ce or V, Zr,
Al-Fe containing transition metal elements such as Mo in Al
A system alloy powder is obtained by a rapid solidification method, and the powder is sintered to form an Al-Fe-X compound in an Al matrix (x represents Ce, V as described above).

The present invention relates to an Al-based alloy powder sintered body in which hot strength is increased by dispersing Zr, Mo, etc.).

Much research and development has been conducted on Al-based alloy powders other than the Al-Fe-based alloy powders shown above. Al-Cr-Zr based alloy powder is disclosed.

[Problems to be Solved by the Invention] All of the sintered bodies obtained from the Al-Fe alloy powder have high tensile strength in the temperature range from room temperature to about 300°C. In addition, these sintered bodies take advantage of the fact that Fe and other alloying elements are difficult to diffuse in Al even at relatively high temperatures, and by finely dispersing compounds of alloying elements in the Al matrix, the strength at high temperatures is improved. It is also known that it is a dispersion-strengthened sintered body.

However, the dispersed phase in the above sintered body is thought to be dispersed in the Al matrix during the rapid solidification process or at an early stage when the powder is hot solidified and formed, and therefore is accompanied by plastic deformation. This is a factor that significantly increases the deformation resistance of the sintered body during the solidification molding process. Moreover, since individual dispersed particles (intermetallic compounds) in the above-mentioned dispersed phase are brittle, the dispersed phase easily becomes a source of cracks during plastic working, reducing the deformability of the sintered body. It is the cause of this.

The Al-based alloy powder sintered body was developed based on the purpose mentioned above, and after sintering and hot forming, it can be processed by hot forging, rolling, extrusion, etc. in the same way as ordinary ingots. (Therefore, the term “sintered body” that can be used in the present invention)
(means the molded material before being processed into a product), Al-
If we try to plastically process Fe-based alloy powder sintered bodies into products (or parts) of various shapes, we not only need press equipment such as extruders and forging machines that have a large capacity commensurate with large deformation resistance. From the viewpoint of preventing cracking during plastic deformation, processing conditions such as temperature and press speed must be carefully selected.

On the other hand, regarding the Al-Cr-Zr alloy powder, is it sudden?
When 4I solidifies, Cr and Zr are forcibly dissolved in Al to form a supersaturated solid solution. It is known that when such a powder is heat-treated after sintering, the supersaturated solid solution phase decomposes and contributes to strengthening, forming a so-called precipitation-strengthened At-based alloy sintered body. However, Al-C
Most of the research to date on r-Zr alloy powders has focused on the Al-Cr-Zr ternary alloy itself, and has not focused on products solidified using Al-Cr-Zr ternary alloy powders. There are not many examples of investigating the characteristics.

The present inventors investigated the properties of Al-Cr-Zr alloy powder sintered bodies containing only Al-Cr-Zr in various proportions, and found that sufficient strength for practical use could be obtained with only the above three components. It turns out there isn't.

The technique disclosed in JP-A-59-116352 further adds Mn to the ternary alloy of Al-Cr-Zr,
Although the resulting sintered body has increased strength, this sintered body has the following problems.

For example, Materials published in April 1986
Science and Technology, Va.
1, 2, pages 394-399, Al-Cr-Zr-
Research on Mn alloy powder has been published, and it is disclosed that the sintered body obtained from this alloy powder is easily affected by the heating conditions during hot extrusion or the like.

Therefore, in order to develop the desired characteristics in a sintered body obtained from this Al-based alloy powder, processing at a relatively low temperature such as room temperature extrusion is required, which requires an extrusion press with great power. Moreover, when the sintered body is subjected to low-temperature extrusion, its strength and deformation resistance in the as-extruded state become too high, making it difficult to forge parts with complex shapes using extruded rods. The amount of forging presses to be applied increases, and cracks are more likely to occur. Furthermore, according to the research conducted by the present inventors, it has been revealed that when the forging process is performed, the strength of the forged material is considerably lower than that of the extruded material.

The present invention was made to solve these technical problems, and its purpose is to have excellent formability after extrusion processing and to increase strength at room temperature and high temperature by heat treatment after forming. A, which is the raw material for the resulting sintered body
The object of the present invention is to provide l-based alloy powder.

[Means for solving the problem] The Al-based alloy powder of the present invention that achieves the above object is
In addition to containing r: 2 to 5% and Zr: 1 to 2.6% as essential components, Cu: 0.5 to 5% and Ni: 0.
5 to 5% of one or two types selected from 0.5 to 5% in total
%, and the remainder consists of Al and unavoidable impurities.

In addition to the above components, B: 0.1 to 0.5%, F
e: 0.5-2.0%, Ti: 0.5-2%
The object of the present invention can be more effectively achieved by containing 1 fl or two or more selected from the group consisting of 0.1 to 1% in a total of 0.1 to 2%.

[Function] The present inventors focused on the age hardenability of the Al-Cr-Zr based alloy powder sintered body, and investigated the actions and effects of various fourth elements on the Al-Cr-Zra base alloy as described above. Various studies were conducted, including the effects of Mn in conventional techniques.

First, it has been found that the addition of Mn element to the Al-Cr-Zr system does not have the effect of increasing age hardenability, but rather acts on the transition structure and contributes to work hardening. Therefore, in order to improve the strength of a sintered body by adding Mn, it is necessary to introduce high-density dislocation by adding plastic deformation before the precipitation of Mn starts. It is essential to work harden the powder by cold processing the powder or by performing low temperature processing such as cold extrusion before interforming. That is, the strength of the sintered body obtained from the Al-Cr-Zr-Mn alloy powder is closely related to the intricately intertwined high-density dislocation structure in the alloy powder.
This is considered to be the cause of the complicated problems mentioned above.

On the other hand, the present inventors have investigated the effects of Cu on Al-Cr-Zr alloys.
We investigated the effects of and Ni.

According to this study, it was found that these elements have the effect of increasing age hardening ability. That is, by blending an appropriate amount of at least one of these elements, the age hardening ability can be effectively exhibited through heat treatment after forming without adversely affecting the formability of the sintered body, and the resulting product can be heated at room temperature. It has been found that the high temperature strength can be increased.

The effects of each component in the Al-based alloy powder according to the present invention and the reasons for limiting their numerical values are as follows.

Cr: 2 to 5% Zr: 1 to 2.5% Cr and Zr form a supersaturated solid solution in the Al matrix during rapid solidification, but precipitate in the matrix during subsequent hot solidification and heat treatment, resulting in sintering. It has the effect of increasing the strength of the compact at room temperature and high temperature. In order to exhibit this age hardening effect, it is necessary to simultaneously add 2% or more Cr and 1% or more Zr. However, if Cr exceeds 5% or Zr exceeds 2.5%, toughness decreases.

One or two types selected from Cu: 0.5-5% and Ni: 0.5-5% (however, the total is 0.5-5%) Cu and Ni have the above-mentioned age hardening effect caused by Cr and Zr. It has a promoting effect and increases the peak hardness after age hardening.

In order to obtain this effect, 1 fffi of Cu and Ni is required.
Alternatively, it is necessary to add at least 0.5% of the two types in total, but if it exceeds 5%, the toughness will decrease.

B: 0.1-0.5% Fe: 0.5-2% Ti: 0.5-2% and Mn: 0.1-1% 1 fffi or two or more selected from the group consisting of (
However, the age hardenability can be increased by adding Cu and Ni (total of 0.1 to 2%), but in addition to these elements, B, Fe,
By containing one or more selected from the group consisting of Ti and Mn, the effects of the present invention can be achieved more effectively. That is, B, Fe.

Elements such as Ti and Mn are dispersed as intermetallic compounds in the matrix and not only contribute to strengthening by preventing the movement of translocation, but also prevent grain boundary movement by precipitating at grain boundaries and promote recrystallization. Prevent strength loss. In order to exhibit this effect, it is necessary to add it within the above range, but if it is added beyond these ranges, it will lead to a decrease in toughness.

As mentioned above, the Al-based alloy powder according to the present invention is made by turning a melted alloy into a fine powder by a rapid solidification method in order to add a large amount of an element that has a small solid solubility limit in an equilibrium state. Various atomization methods can be used as examples, but the method is not limited in any way, but in order to obtain the desired fine powder, it is preferable to set the quenching rate to 102 deg/sec or more.

[Examples] Example 1 Alloys having various compositions shown in Table 1 below were melted and rapidly solidified by N2 gas atomization to obtain powders with a particle size of 74 μm or less. The cooling rate at this time is 1 based on the microstructure observation results of 7075 alloy made by the same method.
It was estimated to be 0.03 deg/sec or more.

Each powder obtained in Table 1 is mixed with an aluminum alloy (AA) of Ommφ.
Standard 5052) capsules are filled, and each capsule is filled with 3
While heating the capsule to 00° C., the inside of the capsule was vacuum degassed through a degassing tube provided at one end of the capsule, and the powder was vacuum sealed in the capsule. The time required for deaeration was approximately 2 hours.

Next, the capsule was subjected to hot extrusion processing, and the outer skin of the capsule was turned and removed from the obtained extruded rod to obtain a round rod (Al-based alloy powder sintered body) with a diameter of about 15 mm. The capsule heating temperature was 350°C, and the time required for heating was about 1 hour.

The following various tests were conducted on each round bar sample thus obtained.

First, in order to find the optimal heat treatment conditions, each sample was
Vickers hardness at room temperature (Hv) when kept at ℃ for various times
) was measured.

The results are shown in Table 2 below, in correspondence with the powder numbers. In Table 2, the symbols F and T mean the respective peak hardnesses of the as-extruded and heat-treated materials. Also, as a representative example,
No. 1.2 (based on example powder) and No. 12
．． The measurement results for No. 13 (using the comparative powder) are shown in FIG.

As a result, for all samples, approximately 350℃×24
It was found that the peak intensity can be obtained by time.

Therefore, the present inventors conducted a test at 350°C x 2 for all samples.
A tensile test was conducted on these heat-treated materials after heat treatment for 4 hours. The results are also listed in Table 2 below. The tensile test was conducted in accordance with ASTM B557M, ASTM 602, and ASTM E21, and the yield strength (σ., 2) and strength (σa) of the smooth test piece at room temperature, the strength (087 g) of the notched test piece, and the strength at 250°C High temperature strength (σ,) was measured. For evaluation of toughness, the ratio (σsrs/σ) of the strength (σNTS) and proof stress (σ.2) is used.

, 2) was used.

The following considerations can be made from the results shown in Figure 1. First, No. 13
Although the Al-Cr-Zr ternary alloy powder sintered body exhibits clear age hardenability, its strength level is low.

Moreover, the Al-Cr-Zr-Mn alloy powder sintered body No. 12 shows high strength even in the as-extruded state and has poor formability), and no age hardenability is observed.

On the other hand, the hardness of the sintered body No. 1.2 (based on the example powder) in the extruded state was Al-Cr-Zr-
The peak hardness is lower (good moldability) than Mn-based hardness, and the peak hardness is higher, and the effect of adding Cu and Ni is significant.

Furthermore, as is clear from the results in Table 2, the sintered body obtained from the alloy powder of the present invention has low hardness as extruded;
It is understood that it has high strength and high toughness after heat treatment.

Thick groove J1 No. 1 created by the method described above. Using each extruded material (F material) No. 2 (made using the example powder) and No. 12 (made using the comparative example powder), the deformation resistance when heated to 350°C was measured, and the deformation resistance was measured at the same temperature. It was hot forged to a thickness of 5 mm. The holding time required for heating was about 1 hour. Also, the deformation resistance is 15mm* x 30mmh
A weight was dropped onto the sample, and the drop hammer method was used to calculate the correlation between the potential energy of the weight and the amount of deformation of the sample.

Then, the plate material obtained by the above forging process was heated to 350°C.
After further aging treatment for 24 hours, the room temperature strength was measured.

The results are shown in Table 3 below, and from this result No. 1
It is understood that the extruded material obtained from the Al-Cr-Zr-Mn alloy powder of No. 2 has higher deformation resistance than the extruded material obtained from the alloy powder of the present invention. Also, it is clear when comparing and considering the results in Table 2 above and Table 3 below, that No.
, 12, the strength after heat treatment of forged material is lower than that of extruded material, whereas No.
It is understood that this decrease in strength is not observed in the material of the present invention of No. 1.2.

Table 3 [Effects of the Invention] As described above, according to the present invention, by using the Al-based alloy powder having the above composition, it is possible to achieve improved strength at room temperature and high temperature, and to obtain an Al-based alloy powder with excellent formability and toughness. An alloy powder sintered body was realized. This sintered body is ideal for various uses such as connecting rods and other engine parts, and the outer skins of aircraft and flying objects, which have complex shapes and require high strength at room and high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a graph showing age hardening curves of various At-Cr-Zr based alloy powder sintered bodies.

Claims (2)

[Claims] (1) In addition to containing Cr: 2 to 5% (meaning by weight %, the same applies hereinafter) and Zr: 1 to 2.8% as essential components, Cu: 0
．． 5-5% and one or two selected from Ni: 0.5-5% in a total of 0.5-5%, with the remainder consisting of Al and inevitable impurities. Alloy powder. (2) B: 0.1-0.5%, Fe: 0.5-2%, T
The sintered material according to claim (1), wherein the sintered product contains a total of 0.1 to 2% of one or more selected from the group consisting of i: 0.5 to 2% and Mn: 0.1 to 1%. Al-based alloy powder for use.