JP2807374B2 - High-strength magnesium-based alloy and its solidified material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength and ductile magnesium-based alloy obtained by a rapid solidification method and a magnesium-based alloy integrated solidified material obtained by integrating and solidifying a material obtained by a rapid solidification method.

[0002]

2. Description of the Related Art Conventional magnesium-based alloys include Mg-
Al-based, Mg-Al-Zn-based, Mg-Th-Zn-based, M
g-Th-Zn-Zr system, Mg-Zn-Zr system, Mg-
Component alloys such as Zn-Zr-RE (rare earth elements) are known, and are used in a wide range of applications as lightweight structural members according to their material properties. Further, as a material obtained by the rapid solidification method, an alloy described in JP-A-3-47941 is known.

[0003]

However, the conventional magnesium-based alloys of the above-mentioned various systems generally have low hardness and strength at present, and Japanese Patent Application Laid-Open No. 3-479 / 1991.
The alloy disclosed in Japanese Patent Publication No. 41 is excellent in hardness and tensile strength, but leaves room for improvement as a material requiring high toughness. Further, JP-A-3-47
The alloy disclosed in No. 941 is obtained as a powder or a ribbon by a liquid quenching method, and when these are used as raw materials in various processes to obtain a final product, that is, when a product is formed only by primary processing, the hardness and In terms of strength,
Although it is excellent, when a solidified material is formed using the powder or flake as a raw material and further processed, that is, in the case of secondary processing, the workability and the excellent characteristics of the material after processing are maintained. There is room for improvement.

In view of the above, the present invention provides a magnesium-based alloy having high hardness and high strength, which is useful as a material requiring high toughness, and secondary processing (extrusion, forging, cutting, etc.). It is an object of the present invention to provide an aluminum-based alloy integrated solidified material having a specific composition that can be easily processed when applied and can maintain the excellent properties of the raw material even after the processing.

[0005]

SUMMARY OF THE INVENTION The first aspect of the present invention have the general formula: Mg _bal X _a Ln _b (However, X is Zn, Ni, C
at least one element selected from u, Ln is Y, L
at least one element selected from a, Ce, and Mm;
a and b are atomic percent, 1 ≦ a ≦ 10, 1 ≦ b ≦ 2
In the fine crystalline structure Tona Ru magnesium-based alloy represented by 0), the fine crystalline structure is H. C. P. M
intermetallic compound in g matrix Mg-Ln based only the body
A high-strength magnesium-based alloy characterized by being uniformly dispersed by 10 to 50% in moment .

A second aspect of the present invention have the general formula: Mg _bal X _a
Ln _b (where X is at least one element selected from Zn, Ni and Cu, Ln is at least one element selected from Y, La, Ce and Mm, a and b are atomic percentages and 1 ≦ a ≦ 10 in 1 ≦ b ≦ 20) fine crystalline structure Tona Ru magnesium-based alloy represented by the above fine crystalline structure is H. C. P. Mg matrix
-A high-strength magnesium-based alloy integrated solidified material obtained by integrating and solidifying a material in which only an Ln-based intermetallic compound is uniformly dispersed in a volume ratio of 10 to 50% .

[0007] Specific examples of Mg-Ln intermetallic compounds include Mg ₁₇ Ce ₂ , Mg ₁₂ Ce ₁ , and Mg ₁₂ L
a ₁ , Mg ₁₇ La ₂ , Mg ₁₇ Y ₃ , and Mg ₅ Y ₂ can be exemplified.

[0008] These intermetallic compounds are described in C. P. Of in Mg matrix, in which are 10-50% distribution by volume, which in the case of less than 10%, room-temperature strength is not sufficient, when it exceeds 50%, the poor ductility at room temperature, to give This is because there is a problem that the processing of the material cannot be performed sufficiently. Further, these intermetallic compounds are described in C. P. In the Mg matrix of
Preferably it is 5 to 40%.

In the above, as the intermetallic compound uniformly dispersed in the Mg matrix, an Mg-Ln-based intermetallic compound is useful in terms of improvement of mechanical properties and toughness, and an Mg-X-based intermetallic compound is used. When precipitated, the obtained material becomes brittle, so that the alloy structure needs to precipitate only the Mg-Ln intermetallic compound in the Mg matrix.

In the magnesium-based alloy of the present invention, a is limited to the range of 1 to 10 at% and b is limited to the range of 1 to 20 at%, respectively, in order to form a supersaturated solid solution exceeding the solid solubility limit, and to quench the liquid. This is for obtaining an alloy composed of fine crystals by an industrial quenching means utilizing a method or the like.

More importantly, by setting the above range, H. C. P. Mg is precipitated, and this fine H. C. P. The reason for this is that finer intermetallic compounds that generate at least Mg and Ln precipitate out of Mg and are uniformly and finely dispersed. The above H. C. P. M
By uniformly and finely dispersing the intermetallic compound composed of at least Mg and Ln in the g matrix, the Mg matrix can be strengthened and the strength of the alloy can be drastically improved. It is to be noted that a material containing at least an amorphous phase in an amount where a is more than 10 at% and / or b is more than 20 at% is obtained, and by heating this at a specific temperature, the phase can be decomposed. When the product of this condition was prepared by thermal decomposition, C. P. The intermetallic compound tends to precipitate simultaneously with or preferentially to Mg, and the intermetallic compound composed of Mg and X tends to precipitate, resulting in reduced toughness. Further, the amount of a is 10 at%.
In the case of an alloy in which b exceeds 20 and / or the amount of b exceeds 20 at%, an alloy similar to the above can be obtained by lowering the cooling rate. Since only the material having a low toughness can be obtained, only the material having low toughness can be obtained.

The X element is at least one element selected from Zn, Ni and Cu, and these elements have the effect of solid solution strengthening in Mg and improving mechanical properties.

The Ln element is at least one element selected from the group consisting of Y, La, Ce, and Mm, and these elements form a stable or metastable intermetallic compound with the magnesium element, and are contained in the magnesium matrix (α phase). The hardness and the strength of the alloy are remarkably improved, the coarsening of fine crystals at high temperatures is suppressed, and heat resistance is imparted. In particular, the alloy of the present invention can improve the mechanical properties.
A g-Ln intermetallic compound can be formed. In addition, Mg-
By specifying the volume ratio of the Ln-based intermetallic compound to be 10 to 50%, excellent ductility can be imparted.

The magnesium-based alloy of the present invention can be obtained by rapidly solidifying a molten alloy having the above composition by a liquid quenching method. The liquid quenching method refers to a method of rapidly cooling a molten alloy, and for example, a single roll method, a twin roll method, a spinning in liquid spinning method, and the like are particularly effective. In these methods, 10 ² to 10 ⁸ K is used. / Sec. Is obtained. In order to manufacture a ribbon material by the single roll method, the twin roll method, or the like, it is necessary to pass approximately 300 mm through a nozzle hole.
The molten metal is jetted onto a roll of, for example, copper or steel having a diameter of 30 to 300 mm and rotating at a constant speed in the range of 1 to 10,000 rpm. As a result, various types of ribbon materials having a width of about 1 to 300 mm and a thickness of about 5 to 500 μm can be easily obtained. Further, in order to produce a fine wire material by the spinning method in a rotating liquid, a depth of about 1 to 10 cm held by a centrifugal force in a drum rotating at about 50 to 500 rpm at a back pressure of argon gas through a nozzle hole. By blowing the molten metal into the solution refrigerant layer, a thin wire material can be easily obtained. At this time, the angle between the molten metal jetted from the nozzle and the refrigerant surface is about 6 °.
It is preferable that the relative velocity ratio between the jetted molten metal and the solution refrigerant surface be about 0.7 to 0.9.

It is to be noted that a quenched powder can be obtained by pulverizing a thin film by a sputtering method, a spray roll method such as a high-pressure gas spraying method, or the above-mentioned ribbon or the like, instead of the above method.

The alloy of the present invention can be obtained by the above-described single roll method, twin roll method, spinning method in a rotating liquid, sputtering method, spray roll method, mechanical alloying method, mechanical gliding method and the like. The average crystal grain size, the average particle size of the intermetallic compound, and the volume ratio of the intermetallic compound can be controlled by selecting appropriate production conditions as needed.

Furthermore, although an amorphous structure can be obtained depending on the composition, this amorphous structure is decomposed into crystalline at a specific temperature or higher when heated. The alloy of the present invention can also be obtained by thermal decomposition of the amorphous structure. At this time, the above-mentioned particle size and volume ratio can be controlled by appropriately selecting the heating conditions.

The method for producing a magnesium-based alloy integrated solidified material of the present invention is also characterized in that a material having the composition represented by the above general formula is melted and rapidly solidified, and the obtained powder or flake is assembled to perform ordinary plastic working. This is a method characterized by pressure-forming and solidifying by means. In this case, the powder or flake used as a raw material may be amorphous, a supersaturated solid solution, or a fine crystalline material having an average crystal grain size of 5 μm or less as described above and an average particle size of the intermetallic compound of 5 μm or less, or a mixed phase thereof. It is necessary to be. In the case of an amorphous material, 50 ° C to 40 ° C during assembly
By heating to 0 ° C., a fine crystalline or mixed phase under the above conditions can be obtained.

The above-mentioned ordinary plastic working technique is in a broad sense, and includes pressure molding and powder metallurgy techniques.

The reason why the average crystal grain size of the Mg matrix is limited to 5 μm or less in the solidified magnesium-based alloy material of the present invention is that if it exceeds 5 μm, the strength is sharply reduced and a high strength material cannot be obtained. In order to obtain a high-strength solidified material, 5 μm or less is required. In addition, the reason why the average particle size of the intermetallic compound is limited to 5 μm or less is that if the average particle size exceeds 5 μm, the dispersed particles become too large to maintain the strength and act as a reinforcing element. It is because it disappears. Further, the average particle size of the intermetallic compound is 1 μm.
The following is desirable.

The solidified magnesium-based alloy material of the present invention has an average crystal grain size,
The average particle size of the intermetallic compound and the dispersion state of the intermetallic compound can be controlled, but if the strength is important, the average crystal grain size and the average particle size of the intermetallic compound are controlled to be small, and if the ductility is important, the Mg matrix By controlling the amount of the intermetallic compound precipitated therein, it is possible to obtain one suitable for various purposes.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 A magnesium-based alloy powder having the component composition shown in Table 1 was prepared using a spray roll device. After filling the produced magnesium-based alloy powder into a metal capsule, a billet for extrusion is produced while performing degassing at a temperature of 200 to 450 ° C. by a vacuum hot press. This billet was extruded at a temperature of 200 to 550 ° C (preferably 250 to 400 ° C) using an extruder.

Under the above manufacturing conditions, 18 types of solidified materials (extruded materials) having the compositions (atomic%) shown in the left column of Table 1 were obtained.

The mechanical properties (tensile strength, hardness, elongation) shown in the right column of Table 1 were examined for each sample (extruded material; solidified material) obtained under the above manufacturing conditions. Hardness (Hv)
Value measured with a micro Vickers hardness tester with a load of 25 g (DP
N). In Table 1, the results of TEM observation are clearly shown for the main precipitated intermetallic compound phases and their volume ratios.

[0026]

[Table 1]

As shown in Table 1, each sample had a hardness Hv
(DPN) is 79 or more, tensile strength is 403 (MPa) or more, and elongation is 4.1 (%) or more, showing excellent characteristics.

Example 2 An extruded material (solidified material) of Mg _bal Zn ₂ Ce _X was prepared in the same manner as in Example 1 above, and an MgCe-based intermetallic compound (Mg
The relationship between the volume fraction of ₁₇ Ce ₂ , Mg ₁₂ Ce ₁ ) and tensile strength and elongation was examined.

FIG. 1 shows the result.

The volume ratio of the intermetallic compound was measured by using a method of image analysis using a TEM for the obtained solidified material. The intermetallic compounds precipitated from the sample were mainly Mg ₁₇ Ce ₂ and Mg ₁₂ Ce ₁ .

FIG. 1 shows that the tensile strength of the intermetallic compound rapidly increased to 15% by volume, and decreased (suddenly) when it exceeded 40%. The elongation gradually increased with the increase of the intermetallic compound. It can be seen that, at 55%, the elongation is at least lower than the elongation required for general processing of 2%.
The volume ratio of 30% of the alloy composition was Mg ₈₈ Zn ₂ Ce _10.

[0032] In the same manner as in Example 3 above in Example 1 to prepare extruded material Mg _bal Cu ₅ La _X a (consolidated material) of MgLa intermetallic compound (M
The relationship between the volume fraction of g ₁₇ La ₂ and Mg ₁₂ La ₁ ) and the tensile strength and elongation were examined.

FIG. 2 shows the result.

From FIG. 2, it can be seen that the tensile strength of the intermetallic compound rapidly increases to 15% by volume and decreases rapidly when it exceeds 40%, and the elongation gradually decreases with the increase of the intermetallic compound. It can be seen that the elongation at 55% is lower than the minimum required elongation of 2% for general processing (in addition,
Volume of 35% of the alloy composition was Mg ₈₅ Cu ₅ La _10).

Example 4 An extruded material (solidified material) of Mg _bal Ni ₄ Y _X was prepared in the same manner as in Example 1 above, and a MgY-based intermetallic compound (Mg ₁₇ Y) was prepared.
₃ , the relationship between the volume fraction of Mg ₅ Y ₂ ) and the tensile strength and elongation was examined.

FIG. 3 shows the result.

FIG. 3 shows that the tensile strength of the intermetallic compound rapidly increased to about 15% by volume, and rapidly decreased when it exceeded about 40%. The elongation gradually increased with the increase of the intermetallic compound. It can be seen that the ratio rapidly decreases when it exceeds about 40%. In addition, it can be seen that the minimum elongation of 2% required for general processing is obtained at a volume ratio of 55% or less. The alloy composition of 33% by volume is Mg
₈₆ Ni ₄ Y ₁₀ .

Further, as a result of TEM observation of the samples of Examples 1 to 4, it was found that the sample was a matrix of magnesium or a supersaturated solid solution of magnesium having an average crystal grain size of 5 μm or less, and that various types of matrix elements and Ln elements were formed. The particles composed of the intermetallic compound were uniformly distributed in the matrix, and the average particle size of the intermetallic compound was 5 μm or less.

[0039]

As described above, the magnesium-based alloy of the present invention is useful as a material having high hardness, high strength and high toughness.

The solidified magnesium-based alloy material of the present invention can be easily processed when performing secondary processing (extrusion, forging, cutting, etc.), and is manufactured by a rapid solidification method even after the processing. The excellent characteristics of the raw material can be maintained.

[Brief description of the drawings]

FIG. 1 is a graph showing test results of Example 2.

FIG. 2 is a graph showing test results of Example 3.

FIG. 3 is a graph showing test results of Example 4.

Claims (5)

(57) [Claims] 1. A general formula: Mg _bal X _a Ln _b (However, X
Is at least one element selected from Zn, Ni, and Cu; Ln is at least one element selected from Y, La, Ce, and Mm (Misch metal); a and b are atomic percentages; 1 ≦ a ≦ 10; in ≦ b ≦ 20) fine crystalline structure Tona Ru magnesium-based alloy represented by the above fine crystalline structure is H. C. P. M in the Mg matrix
The g-Ln-based intermetallic compound is 10 to 50% by volume.
A high-strength magnesium-based alloy characterized by being uniformly dispersed. 2. The method according to claim 1, wherein the Mg-Ln intermetallic compound is at least Mg ₁₇ Ce ₂ , Mg ₁₂ Ce ₁ , Mg ₁₂ La ₁ , Mg _{17
La 2, Mg 17 Y 3,} Mg 5 Y 2 is a claim 1 high-strength magnesium-based alloy according. 3. General formula: Mg _bal X _a Ln _b (where X
Is at least one element selected from Zn, Ni, and Cu; Ln is at least one element selected from Y, La, Ce, and Mm; a and b are atomic percentages, and 1 ≦ a ≦ 1
In 0,1 ≦ b ≦ 20) fine crystalline structure Tona Ru magnesium-based alloy represented by the above fine crystalline structure is H, C, the volume ratio intermetallic compound of the Mg matrix Mg-Ln based only P A high-strength magnesium-based alloy laminated solidified material obtained by laminating and solidifying a material uniformly dispersed in 10 to 50% . 4. The high-strength magnesium-based alloy laminated solid according to claim 3 , wherein the particle size of the Mg matrix and the average particle size of the intermetallic compound are 5 μm or less. 5. The Mg—Ln intermetallic compound is at least Mg ₁₇ Ce ₂ , Mg ₁₂ Ce ₁ , Mg ₁₂ La ₁ , and Mg ₁₇ L.
_{a 2, Mg 17 Y 3,} Mg 5 Y 2 is a claim 3 or 4 high strength magnesium-based alloy compacted and consolidated material according.