JP3238516B2 - High strength magnesium alloy and method for producing the same - 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 magnesium alloy and a method for producing the same, and more particularly to a technique for increasing the strength and toughness of a microcrystalline magnesium alloy.

[0002]

2. Description of the Related Art Applicants have filed Japanese Patent Application No. 3-74881 (filed on Mar. 14, 1991) and European Patent Publication No. 05.
No. 03880, Mga Mb Alc Xd Ze (where M is La, Ce, and / or Mm (mish metal), X is Ni and / or Cu, Z is Mn, Zn, Zr and / or Ti, a = 70 to 90 at%, b = 2 to 15 at
%, D = 2 to 15 at%, e = 0.1 to 8 at%, a +
A high-strength heat-resistant amorphous magnesium alloy having a composition of (b + c + d + e = 100 at%) was proposed. The tensile strength of this alloy is about 80 to 100 kg / mm 2 in the embodiment, and is much higher than that of the conventional magnesium alloy.

[0003]

However, since the above magnesium alloy has an amorphous structure, its form is limited to foil or the like, and there is a problem in practical use as various parts. Accordingly, an object of the present invention is to provide a magnesium alloy having high strength, excellent toughness, and capable of being processed into various shapes, and a method for processing the same.

[0004] The first of the present invention to achieve the above object is as follows.
In the general formula, Mg _a Zn _b X _c (where X is Y, Ce, L
One or more elements selected from the group consisting of a, Nd, Pr, Sm, and Mm (Misch metal), 87 at% ≦ a ≦ 98 at%, b and c are points A and B in FIG. Except on the connecting line, on the BCDEFA line and on the AB-
A range surrounded by a line of CDEF and 0 ≦ Y
(Yttrium) ≦ 4.5 atomic%, 0 ≦ Ce, La, N
It has a composition represented by d, Pr, Sm, and Mm ≦ 3 atomic%, and is characterized in that a Mg—Zn-based and Mg—X-based intermetallic compound is dispersed in a parent phase composed of submicron microcrystals. A high-strength magnesium alloy powder solidified material having excellent toughness. The second aspect of the present invention is a general formula of Mg _a Zn _b X _c (where X is Y, Ce, La, Nd, Pr, Sm, Mm).
(Misch metal) One or more elements selected from the group consisting of 87 atomic% ≦ a ≦ 98 atomic%, b and c are BCD except for the line connecting points A and B in FIG. -E-
It is the range enclosed by the line of FA and the line of ABCDCEF, and 0 ≦ Y (yttrium) ≦ 4.5 atomic%, 0 ≦ Ce, La, Nd, Pr , Sm, Mm ≦ 3 atomic% is rapidly solidified, and then the rapidly solidified alloy is subjected to plastic working at a temperature of 300 to 450 ° C. to form a parent phase composed of submicron microcrystals. Mg-
A method for producing a high-strength magnesium alloy powder solidified material, in which Zn-based and Mg-X-based intermetallic compounds are dispersed.

[0005] In the magnesium alloy according to the first aspect of the present invention, Mg is an element for forming microcrystals to be a parent phase.
If the amount of Mg is less than 87 atomic%, the feature of the magnesium alloy that it is lightweight is lost, the crystal of the parent phase becomes coarse, and the toughness is reduced. On the other hand, when the amount of Mg is 9
If it exceeds 8 atomic%, the amount of the intermetallic compound precipitated in the mother phase becomes insufficient, resulting in a decrease in strength.

[0006] Zn forms an intermetallic compound with Mg, and this intermetallic compound is finely dispersed in a fine Mg matrix to increase the strength without impairing the toughness. X is Y, C
e, La, Nd, Pr, Sm, Mm (Misch metal)
One or more elements selected from the group consisting of
In addition to miniaturizing the matrix of g, an intermetallic compound with Mg is formed, and the intermetallic compound is finely dispersed in the fine Mg matrix to increase the strength without impairing the toughness. It is necessary that the amounts of these elements be in the range shown in FIG. That is, since the dispersed intermetallic compound is coarsened above the AFE line, to the right of the ED line, and below the BCD line to make the material brittle, it is necessary to set the range above or within the range surrounded by these lines.

Furthermore, when Y (yttrium) is added, Y (yttrium) and Mg which precipitate in the alloy of the present invention are added.
Is an intermetallic compound of Ce, La, Nd, Pr, Sm, M
Atomic% of the X element is higher than that of the intermetallic compound of m and Mg. Therefore, when Y (yttrium) is added, 4.
No embrittlement up to 5 atomic%. On the other hand, Ce, La, N
In the case of d, Pr, Sm, and Mm, the upper limit needs to be 3 atomic%.

Next, the structure of the magnesium alloy of the present invention will be described. This alloy is composed of a Mg parent phase (a phase having a crystal structure of Mg) and a dispersed phase of an Mg-Zn-based or Mg-X-based intermetallic compound, and the dispersed phase is finely dispersed in the matrix. I have. The Mg parent phase is a submicron microcrystal, in which a finer intermetallic compound phase is dispersed.

Further, a description will be given of a second method for processing a magnesium alloy according to the present invention. In this method, a molten Mg alloy having the above composition is rapidly solidified. The resulting alloys, amorphous structure showing a specific halo pattern by X-ray diffractometry, the diffraction peak fine crystalline or halo pattern showing a crystal characteristic diffraction peaks are mixed amorphous mixed structure of crystalline Is one of

This alloy is processed at a temperature of 450 ° C. or less. By this processing, the amorphous structure among the above-mentioned structures is changed to a microcrystalline structure in which an intermetallic compound is dispersed, and a desired structure is obtained. In the case of the fine crystalline material, although a slight grain growth occurs, a desired structure can be obtained without coarsening due to recrystallization. The processing can be performed by a plastic working method such as drawing, rolling, forging, or extrusion, and the obtained bulk material has various shapes such as a cylinder, a plate, and an irregular shape. Hereinafter, embodiments of the present invention will be further described.

The quenching and solidification of the molten Mg alloy can be performed by a gun method, a piston-anvil method, a centrifugal method for producing a continuous ribbon, a single-roll method, a twin-roll method, which is generally known as a rapid solidification method. Or a spray method to make powder,
A spinning method in a rotating liquid for producing a fine wire can be used. Among these methods, a single roll method, a twin roll method, or a high pressure gas injection method, which can easily obtain a cooling rate of 10 2 to 10 6 K / s, is particularly suitable.

In order to produce an Mg alloy ribbon by a single roll method or a twin roll method, a molten alloy is injected into a copper or steel nozzle having a diameter of 30 to 300 mm rotating at 300 to 10000 rpm. Thereby, a ribbon having a width of 1 to 300 mm and a thickness of 5 to 500 μm is obtained.

In order to obtain a Mg alloy ribbon by the high-pressure gas injection method, it is necessary to apply 4 to 4 times to the molten alloy flowing down from the molten metal nozzle.
A high-pressure nitrogen gas, argon gas, helium gas, or the like of 15 MPa is blown, and the molten metal is finely divided and simultaneously solidified by rapid cooling.

The Mg alloy obtained by the above-mentioned rapid solidification method can be subjected to plastic working as it is. However, in the case of a thin ribbon or a thin wire, it is pulverized and then filled in a can made of copper, aluminum or an alloy thereof. Plastic working is preferred. At this time, it is preferable to handle the rapidly solidified powder in a highly clean atmosphere having an oxygen content of 1 ppm or less in order to suppress oxidation of the rapidly solidified material from rapid solidification to filling in a metal can.
Further, it is preferable that the powder filled in the metal can be subjected to vacuum degassing prior to plastic working. Processing temperature is 200
It is preferable that the temperature is not lower than ° C. If the processing temperature is less than 200 ° C., solidification and bulking of the powder become difficult.

[0015]

The MgA Znb Xc alloy in which the matrix structure is microcrystalline and a specific intermetallic compound is dispersed in the matrix has both strength and toughness. With the above-described composition, the coarsening of the structure is unlikely to occur by processing, so that a bulk material having a shape close to a part can be obtained while maintaining high strength and high toughness. Hereinafter, the present invention will be described in more detail with reference to examples.

[0016]

EXAMPLES Example 1 Nos. 1 to 3 of Examples of the present invention whose chemical compositions are shown in Table 1 and
The Mg alloy of Reference Example No. 4 was subjected to high frequency melting in an Ar atmosphere to produce a mother alloy. This master alloy was melted at 775 ° C. in a high-frequency furnace in an Ar atmosphere, and then 9.8 MPa Ar was melted.
The powder was made of fine crystalline metal by high-pressure gas injection with a gas.

Among the atomized powders, those having a small particle diameter are more rapidly cooled, and the precipitated particles are small and the solid solution amount of the added element is large. Then, the obtained powder is classified, and a powder having a diameter of 25 μm or less is extruded at a temperature of 300 to 400 ° C. and a pressure of 400 to 1000 MPa at an extrusion ratio of 10: 1 to obtain a cylindrical material having a diameter of 6 mm, a length of 270 mm and a density of 100%. Obtained. The atmosphere to which the powder was exposed during the stages from powder preparation to extrusion had an oxygen partial pressure and a water vapor partial pressure of 1 pp both.
m or less.

When the columnar material was subjected to X-ray diffraction, intermetallic compounds shown in Table 1 were observed together with the Mg phase. The average particle size of the Mg matrix was about 0.3 μm and the average grain size of the intermetallic compound was about 50 nm, and it was observed by TEM that the fine intermetallic compound was dispersed in the fine matrix. .

Next, the columnar material was subjected to a tensile test using an Instron type tensile tester. The results are also shown in Table 1. It turns out that the tensile strength of the Mg alloy of the present invention is 600 to 700 MPa, which is an extremely high value.

[0020]

[Table 1] Composition Extrusion Intermetallic phase Tensile hardness Temperature ℃ MP a Hv 1 Mg95Zn2Mm3 300 Mg17La2, Mg12Nd, CeMg12, Mg2Zn3 726 152 2 Mg92Zn5Mm3 400 Same as above 620 150 3 Mg92Zn10Mm2 375 Same as above 610 130 4 Mg95.5Y2.5Mm2 325 Mg17La2, Mg12Nd, CeMg12 160

Example 2 An Mg alloy having a chemical composition shown in Table 2 was melted in the same manner as in Example 1 and rapidly solidified under the same conditions to produce a fine crystalline alloy. This powder was subjected to hot extrusion under the same conditions as in Example 1 to produce a columnar material. Table 2 shows the results of measuring the Vickers hardness of the cylindrical material.

An alloy having the same composition was prepared into a ribbon material by a single roll method, heated to a temperature corresponding to the hot extrusion temperature to obtain the same structure as the extruded material, and the toughness was evaluated by tight bending. . In the contact bending test, it was examined whether the ribbon material could be contact bent without breaking. A material that can be closely bent is a ductile material having toughness, and an impossible material is a brittle material. The results are also shown in Table 2.

[0023]

[Table 2] No Composition Extrusion Intermetallic Compound Phase Adhesion Hardness Temperature ℃ Bending Hv 5 Mg89Zn10Mm1 300 Mg17La2, Mg12Nd, CeMg12, Mg2Zn3 possible 123 6 Mg87Zn10Mm3 400 Same as above possible 180 7 Mg91.5Zn7.5Mm1 300 Same as above possible 121 8 Mg90.5Zn7.5Mm2 300 Same as above possible 130 9 Mg93Zn5Mm2 10300 above 94 above Same as above Possible 115 11 Mg94.5Zn2.5Mm3 300 Same as above Possible 154 12 Mg95.5Zn2.5Mm2 300 Same as above Possible 151

Comparative Example 1 The same test as in Example 2 was performed on an Mg alloy having the composition shown in Table 3. Table 3 shows the results.

[0025]

[Table 3] No Composition Extrusion Intermetallic Compound Phase Adhesion Hardness Temperature ℃ Bending Hv 13 Mg86Zn10Mm4 300 Mg17La2, Mg12Nd, CeMg12, Mg2Zn3 Not possible 301 14 Mg86Zn10Mm4 400 Same as above Not possible 230 230 Not possible 231 19 Mg90Zn10 300 Same as above Not possible 96 20 Mg95Zn5 300 (Mg only) Possible 70 21 Mg97Zn2Mm1 300 Mg17La2, Mg12Nd, CeMg12, Mg2Zn3 Possible 68 All of the comparative examples were found to be brittle or low in hardness.

[0026]

As described above, the Mg alloy of the present invention has both high strength and toughness and is provided as a bulk material such as a columnar material, so that it can be suitably applied to parts requiring high specific strength. Things.

[Brief description of the drawings]

FIG. 1 shows the range of Zn and X components of the present invention,
It is the graph which added the composition point of o.5,6,10.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C22F 1/00 630 C22F 1/00 630K 681 681 683 683 694 694 694B 1/06 1/06 (72) Inventor Ken Masumoto Sendai, Miyagi 3-8-22 Uesugi, Aoba-ku, Aichi-ku (72) Inventor Akihisa Inoue No.1, Kawauchi, Aoba-ku, Sendai-shi, Miyagi 11-806 (72) Inventor Hidehiko Horikiri 1-9-9, Yaesu, Chuo-ku, Tokyo Inside Teikoku Piston Ring Co., Ltd. (72) Inventor Akira Kato 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (56) References JP-A-6-41701 (JP, A) JP-A-5-306424 (JP, A) JP-A-5-70880 (JP, A) JP-A-3-47941 (JP, A) JP-A-3-10041 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB ) C22C 23/00 - 23/06 C22F 1/06

Claims (2)

(57) [Claims] In the general formula, Mg _a Zn _b X _c (where X is one or more elements selected from the group consisting of Y, Ce, La, Nd, Pr, Sm, Mm (Misch metal)) , 87 at% ≦ a ≦ 98 at%, b and c are on the line of BCDDEFA except for the line connecting the points A and B in FIG. 1 and ABCDE. -F, and 0 ≦ Y (yttrium) ≦ 4.5 atomic%, 0 ≦
It has a composition represented by Ce, La, Nd, Pr, Sm, and Mm ≦ 3 atomic%, and a Mg—Zn-based and Mg—X-based intermetallic compound is dispersed in a parent phase composed of submicron microcrystals. High strength magnesium alloy powder solidified material with excellent toughness characterized by: 2. A compound represented by the general formula: Mg _a Zn _b X _c (where X is one or more elements selected from the group consisting of Y, Ce, La, Nd, Pr, Sm, and Mm (Misch metal)) , 87 atomic% ≦ a ≦ 98 atomic%, b and c in FIG. 1
BCDDEFA line excluding the line connecting points A and B
It is a range surrounded by the upper and ABCDEF lines , and 0 ≦ Y (yttrium) ≦ 4.5 atomic%, 0 ≦
An alloy melt having a composition represented by Ce, La, Nd, Pr, Sm, and Mm ≦ 3 atomic% is rapidly solidified, and then the rapidly solidified alloy is subjected to plastic working at a temperature of 300 to 450 ° C.
Mg-Zn based and
A method for producing a high-strength magnesium alloy powder solidified material, wherein an Mg-X-based intermetallic compound is dispersed .