JP7370167B2 - Magnesium alloy wire and its manufacturing method - Google Patents

Description

The present invention relates to a magnesium alloy wire and a method for manufacturing the same.

Magnesium alloys are becoming widely used in the housings of mobile phones and notebook computers, automobile parts, and the bodies of various electrical products.
It is also believed that magnesium alloy wire may also be used.

Patent Document 1 discloses a magnesium alloy wire with a wire diameter of 0.050 mm and an α-Mg phase average crystal grain size of 1.1 μm. However, if the average crystal grain size can be made smaller than this magnesium alloy wire, it is thought that a magnesium alloy wire with higher strength can be realized.

JP 2015-14046 (Paragraph 0115)

An object of one aspect of the present invention is to provide a magnesium alloy wire that is difficult to break even when the wire diameter is reduced to 50 μm or less, and a method for manufacturing the same.
Another object of one aspect of the present invention is to provide a magnesium alloy wire that has high strength by controlling the average crystal grain size of the α-Mg phase to 1 μm or less, and a method for manufacturing the same.

Various aspects of the present invention will be explained below.
[1] In a magnesium alloy wire containing 80 atomic % or more of Mg and having an α-Mg phase,
The wire diameter of the wire is D, the average crystal grain size of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire is L, and it was observed in a cross section cut perpendicular to the longitudinal direction. A magnesium alloy wire that satisfies the following (Formula 41), (Formula 42), and (Formula 43), where d is the average crystal grain size of the α-Mg phase.
(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1 μm (preferably d≦0.5 μm, more preferably d≦0.3 μm, even more preferably d≦0.19 μm, even more preferably d≦0.12 μm, and even more preferably d≦0.1μm)
(Formula 43) 10≦L/d (preferably 43≦L/d, more preferably 54≦L/d, still more preferably 70≦L/d, even more preferably 90≦L/d)

[2] In [1] above,
A magnesium alloy wire, wherein the D and d satisfy the following (Formula 44).
(Formula 44) d/D≦1/100 (preferably 1.15/300 or less, more preferably 1.9/500 or less, still more preferably d/D≦1/300, even more preferably d/D ≦1/500)

[3] In [1] or [2] above,
The magnesium alloys include Mg-Zn-Y alloy, Mg-Zn-Gd alloy, Mg-Zn-(Y-Gd) alloy, Mg-Zn-YX-Z alloy, Mg-Zn-Gd-X-Z. alloy, and Mg-Zn-Y-Gd-X-Z alloy, or pure Mg,
The X is at least one element selected from the group consisting of Al, Ca and Li,
The Z is at least one element selected from the group consisting of rare earth elements, Mn, Si, Zr, Ti, Hf, Nb, Sn, Ag, Sr, Sc, Sb, B, C and Be,
The content of Zn is a atomic %, the content of Y is b atomic %, the content of Gd is b atomic %, the total content of Y and Gd is b atomic %, and the content of X is c A magnesium alloy wire that satisfies the following (Formula 1) to (Formula 6), where the content of Z is d at %.
(Formula 1) 0.1≦a≦3.0
(Formula 2) 0.1≦b≦3.0
(Formula 3) c≦3.0
(Formula 4) d≦1.0
(Formula 5) b≦a+2
(Formula 6) b≧a−1

[4] In [1] or [2] above,
The magnesium alloy has a composition containing x atomic % of Ca, y atomic % of Al, and the balance consisting of Mg,
A magnesium alloy wire characterized in that a and b satisfy the following (Formula 31) to (Formula 33).
(Formula 31) 3≦x≦7
(Formula 32) 4.5≦y≦12
(Formula 33) 1.2≦y/x≦3.0

[5] In [4] above,
A magnesium alloy wire, characterized in that the magnesium alloy contains x1 atomic % of Zn, and x1 satisfies the following (Formula 34).
(Formula 34) 0<x1≦3

[6] In [4] or [5] above,
The magnesium alloy contains x2 atomic % of at least one element selected from the group of Mn, Zr, Si, Sc, Sn, Ag, Cu, Li, Be, Mo, Nb, W, and rare earth elements, and x2 is A magnesium alloy wire characterized by satisfying the following (Formula 35).
(Formula 35) 0<x2≦0.3

[7] In [1] or [2] above,
A magnesium alloy wire, wherein the magnesium alloy is any one of the following alloys (A) to (F).
(A) is a Mg-Al-Mn alloy, and the following (Formula 7) and (Formula 8) are satisfied, assuming that the Al content is e atomic % and the Mn content is f atomic %.
(Formula 7) 2.7≦e≦9.2
(Formula 8) 0.02≦f≦0.07
(B) Mg-Al-Mn-Ca alloy, where the Al content is g atomic%, the Mn content is h atomic%, and the Ca content is i atomic%, the following (Formula 9) ~ ( Formula 11) is satisfied.
(Formula 9) 2.7≦g≦9.2
(Formula 10) 0.02≦h≦0.07
(Formula 11) 0.4≦i≦1.6
(C) is a Mg-Al-Zn alloy, and the following (Formula 12) and (Formula 13) are satisfied, assuming that the Al content is j atomic % and the Zn content is k atomic %.
(Formula 12) 2.7≦j≦8.4
(Formula 13) 0.3≦k≦1.2
(D) Mg-Al-Zn-Ca alloy, where the Al content is 1 atomic %, the Zn content is m atomic %, and the Ca content is n atomic %, the following (Formula 14) to ( Formula 16) is satisfied.
(Formula 14) 2.7≦l≦8.5
(Formula 15) 0.3≦m≦1.2
(Formula 16) 0.4≦n≦1.6
(E) It is a Mg-Nd-Y alloy, and the following (Formula 17) and (Formula 18) are satisfied, assuming that the Nd content is o atomic % and the Y content is p atomic %.
(Formula 17) 0.3≦o≦0.7
(Formula 18) 0.7≦p≦1.4
(F) is a Mg-Al-RE alloy, and the following (Formula 19) and (Formula 20) are satisfied, assuming that the Al content is q atomic % and the RE content is r atomic %.
(Formula 19) 2.2≦q≦4.2
(Formula 20) 0.2≦r≦0.9

[8] In [1] or [2] above,
The magnesium alloy wire has a long-period layered structure phase,
A magnesium alloy wire, wherein the long-period layered structure phase is precipitated within the α-Mg phase.

[9] In any one of the above [1] to [8],
A magnesium alloy wire, wherein the wire has a 0.2% yield strength of 400 MPa or more (preferably 600 MPa or more, more preferably 700 MPa or more).

[10] Step (a) of rapidly solidifying a molten magnesium alloy containing 80 atomic % or more of Mg to produce a plurality of rapidly solidified products;
a step (b) of producing a solidified molded product by hot extruding the plurality of rapidly solidified products;
a step (c) of producing a magnesium alloy base material wire by extruding the solidified molded product;
a step (d) of manufacturing a magnesium alloy wire having an α-Mg phase by subjecting the magnesium alloy base material wire to a plurality of drawing operations;
Equipped with
The cooling rate when rapidly solidifying the molten magnesium alloy is faster than 1000 K/sec (preferably 10000 K/sec),
The temperature of the magnesium alloy base material wire during each of the plurality of drawing operations is 150°C or more and 350°C or less (preferably more than 200°C and 300°C or less), and the drawing speed is 0.1 m/min or more and 100 m/min. The following is
The wire diameter of the wire is D, the average crystal grain size of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire is L, and it was observed in a cross section cut perpendicular to the longitudinal direction. A method for manufacturing a magnesium alloy wire, characterized in that the following (Formula 41), (Formula 42) and (Formula 43) are satisfied, where d is the average crystal grain size of the α-Mg phase.
(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1 μm (preferably d≦0.5 μm, more preferably d≦0.3 μm, even more preferably d≦0.19 μm, even more preferably d≦0.12 μm, and even more preferably d≦0.1μm)
(Formula 43) 10≦L/d (preferably 43≦L/d, more preferably 54≦L/d, still more preferably 70≦L/d, even more preferably 90≦L/d)

[11] In [10] above,
A method for manufacturing a magnesium alloy wire, characterized in that the above D and the above d satisfy the following (Formula 44).
(Formula 44) d/D≦1/100 (preferably 1.15/300 or less, more preferably 1.9/500 or less, still more preferably d/D≦1/300, even more preferably d/D≦ 1/500)

[12] In [10] or [11] above,
A step of heat-treating the magnesium alloy base material wire after at least one of the plurality of drawing operations,
The temperature of the heat treatment is at least 50 °C higher than the temperature of the magnesium alloy base material wire immediately after the drawing process immediately before the heat treatment and at most 400 °C,
A method for manufacturing a magnesium alloy wire, wherein the heat treatment time is 10 seconds or more and 12 hours or less .

[13] In any one of the above [10] to [12],
A method for producing a magnesium alloy wire, characterized in that the magnesium alloy wire obtained in step (d) has a 0.2% yield strength of 400 MPa or more (preferably 600 MPa or more, more preferably 700 MPa or more).

[14] In any one of the above [10] to [13],
A method for manufacturing a magnesium alloy wire, characterized in that the temperature of a die used when performing each of the plurality of drawing operations is set at 200° C. or more and 300° C. or less.

According to one aspect of the present invention, it is possible to provide a magnesium alloy wire that is difficult to break even when the wire diameter is reduced to 50 μm or less, and a method for manufacturing the same.
Further, according to one aspect of the present invention, it is possible to provide a magnesium alloy wire having high strength by setting the average crystal grain size of the α-Mg phase to 1 μm or less, or a method for manufacturing the same.

FIG. 2 is a cross-sectional view for explaining a method for manufacturing a magnesium alloy wire according to one embodiment of the present invention. 2 is a microstructure photograph showing the particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 1, Sample 2, Sample 3, and Sample 4 according to Example 1. . 2 is a microstructure photograph showing the particle size distribution measured by EBSD in a cross section of the wire of Sample 5 according to Example 1. FIG. 3 is a diagram showing the grain size distribution shown in FIG. 2 in terms of the relationship between crystal grain sizes and their ratios. FIG. 4 is a diagram showing the grain size distribution shown in FIG. 3 in terms of the relationship between crystal grain sizes and their ratios. FIG. 3 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 1 to 5. This is a photograph of the structure observed in a cross section (longitudinal cross section) cut in the longitudinal direction of each of the wires of Samples 1 to 4. FIG. 3 is a diagram showing the average crystal grain size (structure length) of the α-Mg phase in the longitudinal cross section of each of Samples 1 to 5. FIG. 3 is a diagram showing the aspect ratio of crystal grains of α-Mg phase. FIG. 3 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 2 to 5. 2 is a microstructure photograph showing the particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 5, Sample 6, Sample 7, and Sample 8 according to Example 2. . 2 is a microstructure photograph showing the particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 9, Sample 10, Sample 11, and Sample 12 according to Example 2. . 2 is a microstructure photograph showing the particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 13, Sample 14, Sample 15, and Sample 16 according to Example 2. . Particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 17, Sample 18, Sample 19, Sample 20, Sample 25, and Sample 26 according to Example 2 This is a photograph of the organization. Particle size distribution when measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 21, Sample 22, Sample 23, Sample 24, Sample 27, and Sample 28 according to Example 2 This is a photograph of the organization. FIG. 12 is a diagram showing the grain size distribution shown in FIG. 11 in terms of the relationship between crystal grain sizes and their ratios. FIG. 13 is a diagram showing the grain size distribution shown in FIG. 12 in terms of the relationship between crystal grain sizes and their ratios. FIG. 14 is a diagram showing the grain size distribution shown in FIG. 13 in terms of the relationship between crystal grain sizes and their ratios. FIG. 15 is a diagram showing the grain size distribution shown in FIG. 14 in terms of the relationship between crystal grain sizes and their ratios. FIG. 16 is a diagram showing the grain size distribution shown in FIG. 15 in terms of the relationship between crystal grain sizes and their ratios. FIG. 7 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 5 to 8. FIG. 7 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 9 to 12. FIG. 3 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 13 to 16. FIG. 3 is a diagram showing the average crystal grain size of the α-Mg phase in the cross sections of Samples 17 to 20, 25, and 26. FIG. 3 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 21 to 24, 27, and 28. These are photographs of the structures observed in cross sections (longitudinal cross sections) cut in the longitudinal direction of the wires of Samples 13 to 16. These are photographs of the structures observed in cross sections (longitudinal cross sections) cut in the longitudinal direction of the wires of Samples 21 to 24, 27, and 28. FIG. 2 is a diagram showing the average crystal grain size (structure length) of the α-Mg phase in the longitudinal cross section of Samples 13 to 16, 21 to 24, 27, and 28. FIG. 3 is a diagram showing the aspect ratio of α-Mg phase crystal grains of samples 13 to 16, 21 to 24, 27, and 28. FIG. 3 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 5 to 8. FIG. 3 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 9 to 12. FIG. 3 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 13 to 16. FIG. 2 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 17 to 20, 25, and 26. FIG. 3 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 21 to 24, 27, and 28.

Embodiments of the present invention will be described in detail below with reference to the drawings. However, those skilled in the art will easily understand that the present invention is not limited to the following description, and that the form and details thereof can be changed in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the contents described in the embodiments shown below.

<Magnesium alloy wire>
One aspect of the present invention is a magnesium alloy wire having a wire diameter of 5 μm or more and 50 μm or less. In detail, this magnesium alloy wire contains 80 atomic % or more of Mg, has an α-Mg phase, has a wire diameter of D, and has α- When the average crystal grain size of the Mg phase is L and the average crystal grain size of the α-Mg phase observed in a cross section cut perpendicular to the longitudinal direction is d, the following (Equation 41), (Equation 42) and (Equation 43). (Formula 43) is the aspect ratio. By reducing the average crystal grain size of the α-Mg phase to 1 μm or less in this manner, high strength or high corrosion resistance of the wire can be achieved.
(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1 μm (preferably d≦0.5 μm, more preferably d≦0.3 μm, even more preferably d≦0.19 μm, even more preferably d≦0.12 μm, and even more preferably d≦0.1μm)
(Formula 43) 10≦L/d (preferably 43≦L/d, more preferably 54≦L/d, still more preferably 70≦L/d, even more preferably 90≦L/d)
Note that the upper limit of the aspect ratio is preferably about 200.

Further, the wire diameter D of the wire and the average crystal grain size d of the α-Mg phase preferably satisfy the following (Formula 44). In this way, by making the average crystal grain size of the α-Mg phase sufficiently smaller than the wire diameter, it is possible to achieve high strength of the wire.
(Formula 44) d/D≦1/100 (preferably 1.15/300 or less, more preferably 1.9/500 or less, still more preferably d/D≦1/300, even more preferably d/D ≦1/500)

Note that in this specification, the wire diameter of the wire means, for example, the wire diameter D of the wire 12 shown in FIG. 1, and when the cross-sectional shape of the wire is not circular, it means the maximum outer diameter of the cross-section of the wire.

In addition, in this specification, the average crystal grain size d of the α-Mg phase observed in a cross section cut perpendicular to the longitudinal direction of the wire refers to It means the average value of particle size distribution obtained from the measurement results of EBSD observation images.

Further, in this specification, the method for determining the average crystal grain size L of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire is as follows. A field of view where the tissue can be clearly observed is selected by SEM observation of the cross section subjected to the CP treatment, and the length of the tissue within the field of view is measured based on the range at the time of measurement. At that time, items whose appearance is ambiguous are excluded from length measurement. The value obtained from the sum of the length measurements and the arithmetic average of the number of measurements is defined as the average crystal grain size L.
Further, in this embodiment, a magnesium alloy wire with a wire diameter in the range of 5 μm or more and 50 μm or less is used, but the wire diameter may be in the range of 10 μm or more and 50 μm or less, or the wire diameter is 15 μm or more and 50 μm or less. The wire diameter may be in the range of 20 μm or more and 50 μm or less, the wire diameter may be in the range of 25 μm or more and 50 μm or less, or the wire diameter is in the range of 30 μm or more and 50 μm or less. It may be.

As the above magnesium alloy, any one of the following alloys [1] to [5] can be used.

[1] Magnesium alloys include Mg-Zn-Y alloy, Mg-Zn-Gd alloy, Mg-Zn-(Y-Gd) alloy, Mg-Zn-YX-Z alloy, Mg-Zn-Gd-X -Z alloy, and Mg-Zn-Y-Gd-X-Z alloy,
The X is at least one element selected from the group consisting of Al, Ca and Li,
The Z is at least one element selected from the group consisting of rare earth elements, Mn, Si, Zr, Ti, Hf, Nb, Sn, Ag, Sr, Sc, Sb, B, C and Be,
The content of Zn is a atomic %, the content of Y is b atomic %, the content of Gd is b atomic %, the total content of Y and Gd is b atomic %, and the content of X is c When the content of Z is d atomic %, it is preferable that the following (Formula 1) to (Formula 6) be satisfied.
(Formula 1) 0.1≦a≦3.0
(Formula 2) 0.1≦b≦3.0
(Formula 3) c≦3.0
(Formula 4) d≦1.0
(Formula 5) b≦a+2
(Formula 6) b≧a−1
Note that rare earth elements include all rare earth elements.

[2] The magnesium alloy has a composition containing x atomic % of Ca, y atomic % of Al, and the balance consisting of Mg,
It is preferable that a and b satisfy the following (Formula 31) to (Formula 33).
(Formula 31) 3≦x≦7
(Formula 32) 4.5≦y≦12
(Formula 33) 1.2≦y/x≦3.0

[3] In [2] above,
It is preferable that the magnesium alloy contains x1 atomic % of Zn, and x1 satisfies the following (Formula 34).
(Formula 34) 0<x1≦3

[4] In [2] or [3] above,
The magnesium alloy contains x2 atomic % of at least one element selected from the group of Mn, Zr, Si, Sc, Sn, Ag, Cu, Li, Be, Mo, Nb, W, and rare earth elements, and x2 is It is preferable that the following (Formula 35) be satisfied.
(Formula 35) 0<x2≦0.3

[5] The magnesium alloy is preferably one of the following alloys (A) to (F).
(A) is a Mg-Al-Mn alloy, and the following (Formula 7) and (Formula 8) are satisfied, assuming that the Al content is e atomic % and the Mn content is f atomic %.
(Formula 7) 2.7≦e≦9.2
(Formula 8) 0.02≦f≦0.07
(B) Mg-Al-Mn-Ca alloy, where the Al content is g atomic%, the Mn content is h atomic%, and the Ca content is i atomic%, the following (Formula 9) ~ ( Formula 11) is satisfied.
(Formula 9) 2.7≦g≦9.2
(Formula 10) 0.02≦h≦0.07
(Formula 11) 0.4≦i≦1.6
(C) is a Mg-Al-Zn alloy, and the following (Formula 12) and (Formula 13) are satisfied, assuming that the Al content is j atomic % and the Zn content is k atomic %.
(Formula 12) 2.7≦j≦8.4
(Formula 13) 0.3≦k≦1.2
(D) Mg-Al-Zn-Ca alloy, where the Al content is 1 atomic %, the Zn content is m atomic %, and the Ca content is n atomic %, the following (Formula 14) ~ ( Formula 16) is satisfied.
(Formula 14) 2.7≦l≦8.5
(Formula 15) 0.3≦m≦1.2
(Formula 16) 0.4≦n≦1.6
(E) It is a Mg-Nd-Y alloy, and the following (Formula 17) and (Formula 18) are satisfied, assuming that the Nd content is o atomic % and the Y content is p atomic %.
(Formula 17) 0.3≦o≦0.7
(Formula 18) 0.7≦p≦1.4
(F) is a Mg-Al-RE alloy, and the following (Formula 19) and (Formula 20) are satisfied, assuming that the Al content is q atomic % and the RE content is r atomic %.
(Formula 19) 2.2≦q≦4.2
(Formula 20) 0.2≦r≦0.9

Note that the above magnesium alloy may contain impurities to the extent that the alloy properties are not affected.

The above magnesium alloy [1] preferably has a crystal structure of an α-Mg phase and a long-period stacked structure phase, and the long-period stacked structure phase is preferably precipitated within the α-Mg phase. The long-period layered structure phase is precipitated within the α-Mg phase in this way by rapidly solidifying a molten magnesium alloy to produce multiple rapidly solidified products, and then hot extruding the multiple rapidly solidified products. This is a characteristic of magnesium alloys manufactured by a rapid cooling method that produces solidified molded products. Further, the magnesium alloy wire of [1] above can have mechanical properties of high strength, high ductility, and high toughness by having a long-period laminated structure phase.

<Method for manufacturing magnesium alloy wire>
A method for manufacturing a magnesium alloy wire according to one embodiment of the present invention will be described with reference to FIG.

First, a magnesium alloy base wire having a small average crystal grain size of the α-Mg phase is produced.
Specifically, a plurality of rapidly solidified products are produced by rapidly solidifying a molten magnesium alloy containing 80 atomic % or more of Mg. The cooling rate at this time is preferably faster than 1000 K/sec (preferably 10000 K/sec). The plurality of rapidly solidified products are, for example, powders produced by the RS-P/M method (or flakes, ribbons, or thin wires produced by the RS-P/M method, or thin wires produced by the molten metal extraction method).

Next, a solidified molded product is produced by hot extruding the plurality of rapidly solidified products. Specifically, a billet is produced by filling a copper can with the powder and vacuum-sealing it, and a solidified molded product can be produced by extruding the billet. Other methods of solidification and molding include rolling the powder with grooved rolls.
Next, the solidified molded product is extruded to produce a magnesium alloy base wire having a small average crystal grain size of the α-Mg phase.

In this embodiment, the magnesium alloy base material wire with a small average crystal grain size of the α-Mg phase is manufactured by rapid solidification powder metallurgy (RS-P/M), but for example, ECAE (equal-channel- A magnesium alloy base material wire having a small average crystal grain size of the α-Mg phase may be produced by a method such as an angular-extrusion processing method in which a huge strain is applied to the material.

The ECAE processing method is a method in which the longitudinal direction of the sample is rotated by 90° in each pass in order to introduce uniform strain into the sample. Specifically, a magnesium alloy casting, which is a forming material, is forcibly entered into the forming hole of a forming die having an L-shaped forming hole in cross section, and in particular, 90% of the L-shaped forming hole is formed. This method applies stress to the magnesium alloy casting at the bent part to obtain a molded body. The number of passes of ECAE is preferably multiple times. The temperature during ECAE processing is preferably, for example, 250°C or more and 500°C or less.

After producing the above magnesium alloy base material wire, the magnesium alloy base material wire is subjected to drawing processing multiple times to produce a magnesium alloy wire having an α-Mg phase. In this specification, "magnesium alloy base material wire" and "magnesium alloy wire" are defined as follows. The magnesium alloy wire refers to a wire that has been subjected to multiple drawing operations. The magnesium alloy base material wire means a wire before being drawn multiple times and a wire that is in the middle of being drawn multiple times. In other words, the magnesium alloy base material wire means all the wires before the drawing process is completed multiple times. For example, if the processing step shown in FIG. 1 is the final drawing process after a plurality of drawing processes, the magnesium alloy base material wire 11 will be the one before this final drawing process, and the magnesium alloy wire after the drawing process. It becomes 12. In addition, when the processing step shown in FIG. 1 is a drawing process in the middle of a plurality of drawing processes, the magnesium alloy base material wire 11 is used before this intermediate drawing process, and the magnesium alloy base material wire 12 is also used after the drawing process. becomes.

The above-mentioned magnesium alloy base material wire is preferably formed of a magnesium alloy that does not (or does not easily) undergo grain growth during heat treatment at a temperature of 300°C, and specifically, any of the above [1] to [5]. Preferably, it is made of an alloy of the following.

As shown in FIG. 1, a magnesium alloy base material wire 11 having a wire diameter of, for example, more than 1 mm and less than 3 mm is pulled out using a die 13 in the direction of the arrow at a speed of 0.1 m/min or more and 100 m/min or less (for example, 7 m/min). A magnesium alloy wire (or a magnesium alloy base material wire in the case of a plurality of drawing operations) is formed by drawing at a drawing speed of 100 min. The temperature of the magnesium alloy base wire 11 during the drawing process (that is, the temperature of the magnesium alloy base wire 11 when passing through the die 13) is 150°C or more and 350°C or less (preferably more than 200°C and 300°C or less). It is recommended that the range is . The reason for setting this temperature range is to prevent the magnesium alloy base wire from breaking during drawing, and to reduce the temperature or time of heat treatment to remove strain after drawing. The reason for reducing the heat treatment temperature or time is that if the temperature or time is small, grain growth of the α-Mg phase can be suppressed.

In this specification, the wire diameter of the magnesium alloy base wire means, for example, the wire diameter d3 of the magnesium alloy base wire 11 shown in FIG. It means the maximum outer diameter of the cross section of the alloy base wire.

When the magnesium alloy base material wire 11 at room temperature is subjected to the first drawing process, heat due to friction between the die 13 and the magnesium alloy base material wire 11 as it passes through the die 13 is transferred to the magnesium alloy base material wire 12 after drawing. The temperature of the dice 13 is controlled in consideration of the addition. For example, the temperature of the dice 13 is controlled at 200°C or more and 300°C or less. Thereby, the temperature of the magnesium alloy base material wire during drawing can be kept within the above range.

When performing the second drawing process, the temperature of the magnesium alloy base material wire 11 is returned to room temperature, and the magnesium alloy base material wire 11 at room temperature is passed through a temperature-controlled die 13 to perform the drawing process. Such drawing process is repeated multiple times until the wire diameter D of the magnesium alloy wire 12 satisfies the following (Formula 41). The magnesium alloy wire 12 that satisfies the following (Formula 41) has an α-Mg phase, where L is the average grain size of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire 12, and It is preferable that the following (Equation 42) and (Equation 43) be satisfied, where d is the average crystal grain size of the α-Mg phase observed in a cross section cut perpendicular to the .

(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1 μm (preferably d≦0.5 μm, more preferably d≦0.3 μm, even more preferably d≦0.19 μm, even more preferably d≦0.12 μm, and even more preferably d≦0.1μm)
(Formula 43) 10≦L/d (preferably 43≦L/d, more preferably 54≦L/d, still more preferably 70≦L/d, even more preferably 90≦L/d)

When performing each of the above-mentioned plurality of drawing operations, it is preferable to supply non-silicon oil to the die 13 as a lubricating oil, for example, it is preferable to supply edible oil. Thereby, the frictional heat between the die 13 and the magnesium alloy base material wire 11 can be reduced, and the wire can be prevented from breaking during the drawing process.

The area reduction rate RA when performing each of the above-mentioned plurality of drawing processes may satisfy the following (Formula 45), preferably the following (Formula 45').
(Formula 45) 3%≦RA≦15%
(Formula 45') 5%≦RA≦12%
Note that the area reduction rate is a value of (1-(D/d3) ² )×100, where d3 is the wire diameter before drawing and D is the wire diameter after drawing.

In addition, as the magnesium alloy base material wire is subjected to a plurality of drawing operations, the wire diameter of the magnesium alloy base material wire 11 gradually becomes smaller. Heat treatment is performed on the magnesium alloy base material wire after at least one of the plurality of drawing operations. The temperature of this heat treatment is preferably at least 50 degrees Celsius higher than the temperature of the magnesium alloy base material wire immediately after the drawing process immediately before the heat treatment and at most 400 degrees Celsius, and the time of the heat treatment is at least 10 seconds and at most 12 hours. good.

The timing of heat treatment is such that the average crystal grain size of the α-Mg phase of the magnesium alloy base material wire after multiple drawing operations is the same as the average grain size of the α-Mg phase of the magnesium alloy base material wire before multiple drawing operations. This is when it becomes much smaller than the crystal grain size. Further, the number of times the heat treatment is performed may be multiple times and may be adjusted as appropriate.

For example, the heat treatment may be performed after each drawing process, or the heat treatment may be performed sometimes or not after the drawing process, rather than after each drawing process. Further, for example, if the heat treatment temperature is 350° C. and the heat treatment time is 30 minutes, it is possible to reduce the formation of an oxide film on the surface of the magnesium alloy wire 12 even if the heat treatment is performed in the air. In other words, even if heat treatment is performed, the formation of an oxide film is reduced.

In this way, with a wire diameter D of 5 μm or more and 50 μm or less, the average crystal grain size d of the α-Mg phase is 1 μm or less (preferably 0.5 μm or less, more preferably 0.3 μm or less, and even more preferably 0.1 μm or less). ) magnesium alloy wire 12 can be manufactured. In this case, the wire diameter D and the average grain size d preferably satisfy the following (Formula 44).
(Formula 44) d/D≦1/100 (preferably 1.15/300 or less, more preferably 1.9/500 or less, still more preferably d/D≦1/300, more preferably d/D≦1 /500)

Further, the 0.2% yield strength of the magnesium alloy wire obtained as described above is preferably 400 MPa or more, preferably 600 MPa or more, and more preferably 700 MPa or more.

According to the above embodiment, a magnesium alloy base material wire with a small crystal grain size is produced by a rapid solidification powder metallurgy method, and then the magnesium alloy base material wire is drawn and heat-treated to suppress recrystallization and grain growth as much as possible. By repeating the process, the average crystal grain size of the α-Mg phase can be made 1 μm or less at a predetermined wire diameter. Thereby, a magnesium alloy wire having high strength or high corrosion resistance can be realized.

Further, even if the wire diameter of the magnesium alloy wire is reduced to 50 μm or less, a wire that is difficult to break can be realized.

FIG. 2 shows cross sections (cross sections) cut perpendicular to the longitudinal direction of the wires of Sample 1, Sample 2, Sample 3, and Sample 4 according to Example 1, when measured by EBSD (Electron Back Scatter Diffraction). Fig. 2 is a microstructure photograph showing the particle size distribution of . FIG. 3 is a microstructure photograph showing the particle size distribution measured by EBSD in a cross section of the wire of Sample 5 according to Example 1.

Sample 1 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified molded product, and its alloy composition is Mg. ₉₇ -Zn ₁ -Y ₂ . Sample 2 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base material wire of Sample 1 to multiple drawing operations and heat treatment. Sample 3 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting Sample 2 to drawing and heat treatment multiple times. Sample 4 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting Sample 3 to drawing and heat treatment multiple times. Sample 5 is a magnesium alloy wire with a wire diameter of 0.05 mm obtained by further subjecting Sample 4 to drawing and heat treatment multiple times.

The method for producing Sample 1 is as follows.
An alloy powder is produced by melting the Mg ₉₇ -Zn ₁ -Y ₂ alloy by gas heating in an argon gas atmosphere and cooling it at a cooling rate of about 2×10 ⁵ K/sec. Next, the alloy powder is preformed at a pressure of 60 to 170 MPa, and vacuum degassed at a temperature of 250° C. for 2 hours to produce a billet. Next, the die and container are fixed, and the billet is pressed against the die to perform extrusion processing. At this time, the extrusion processing conditions are as follows.
Extrusion speed: 2.5mm/min Container, die and billet temperature: 350℃
Extrusion ratio: 15
Wire diameter of sample 1 magnesium alloy base wire: 3 to 15 mm
Note that in this example, a cooling rate of about 2×10 ⁵ K/sec is used, but it is also possible to use a cooling rate in the range of 1×10 ⁵ K/sec or more and 2×10 ⁵ K/sec or less. It is.

The method for producing sample 2 is as follows.
Temperature during drawing of magnesium alloy base material wire: 300°C until the wire diameter of the magnesium alloy base material wire is 1.08 mm, 225°C from wire diameters smaller than that.
Drawing speed: 0.1-1.0m/min Heat treatment temperature: 350℃
Heat treatment time: 10 minutes Heat treatment frequency: Performed every drawing process until the wire diameter of the magnesium alloy base material wire is 1.65 mm, and once every two drawing processes for wire diameters smaller than that Die material: Magnesium alloy base material Carbide dies are used for wire diameters up to 2.13 mm, and diamond dies are used for wire diameters smaller than that.Dice temperature: 300°C for wire diameters of magnesium alloy base material wires of 1.08 mm; 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 2: 1.0 mm
Note that the drawing direction means the direction of the arrow shown in FIG. When the drawing direction has two directions, one direction is the direction of the arrow shown in FIG. 1, and the other direction is the direction of the magnesium alloy base wire 11 rotated by 180 degrees and arranged in the opposite direction. It means the pulling direction.

The method for producing sample 3 is as follows.
Temperature during drawing of magnesium alloy base wire: 225℃
Drawing speed: 1.0m/min Heat treatment temperature: 350℃
Heat treatment time: 10 minutes Heat treatment frequency: Once every 2 to 4 processing steps Die material: Diamond die Die temperature: 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 3: 0.5 mm

The method for producing sample 4 is as follows.
Temperature during drawing of magnesium alloy base wire: 225℃
Drawing speed: 1.0 to 5.0 m/min Heat treatment temperature: 350°C
Heat treatment time: 10 minutes Heat treatment frequency: Once every 3 to 10 processing steps Die material: Diamond die is used Die temperature: 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 4: 0.1 mm

The method for producing sample 5 is as follows.
Temperature during drawing of magnesium alloy base wire: 225℃
Drawing speed: 1.0 to 5.0 m/min Heat treatment temperature: 350°C
Heat treatment time: 10 minutes Heat treatment frequency: Performed once for 12 or more processing steps Die material: Diamond die used Die temperature: 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 5: 0.05mm

FIG. 4 is a diagram showing the grain size distribution shown in FIG. 2 in terms of the relationship between crystal grain sizes and their ratios. FIG. 5 is a diagram showing the grain size distribution shown in FIG. 3 in terms of the relationship between crystal grain sizes and their ratios. FIG. 6 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 1 to 5. FIG. 7 is a photograph of the structure observed in a cross section (longitudinal cross section) cut in the longitudinal direction of each of the wires of Samples 1 to 4. FIG. 8 is a diagram showing the average crystal grain size (structure length) of the α-Mg phase in the longitudinal cross section of each of Samples 1 to 5. FIG. 9 is a diagram showing the aspect ratio of crystal grains of the α-Mg phase.

The method for measuring the average crystal grain size d of the α-Mg phase in the cross section shown in FIG. 6 is as follows.
The wire is cut in a direction perpendicular to the longitudinal direction of the wire, and an EBSD observation image of the cut cross section is measured. The average value of the particle size distribution of the α-Mg phase obtained from the measurement results was defined as the average crystal grain size d of the α-Mg phase.

The method for measuring the structure length (average grain size L) shown in FIG. 8 is as follows.
A field of view where the tissue can be clearly observed is selected by SEM observation of the cross section subjected to the CP treatment, and the length of the tissue within the field of view is measured based on the range at the time of measurement. At that time, items whose appearance is ambiguous are excluded from length measurement. The value obtained from the sum of the length measurements and the arithmetic average of the number of measurements was defined as the average crystal grain size L.

FIG. 10 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 2 to 5. As shown in Figure 10, the wire of sample 2 has a 0.2% yield strength of 571 MPa, the wire of sample 3 has a 0.2% yield strength of 583 MPa, and the wire of sample 4 has a 0.2% yield strength of 638 MPa. The wire of sample 5 has a 0.2% yield strength of 723 MPa.

According to FIG. 10, it can be seen that the 0.2% proof stress of the magnesium alloy wire with a wire diameter of 50 μm or less is 700 MPa or more.
The reason why the magnesium alloy wire can have such high strength is that the average grain size of the α-Mg phase is made small as shown in Figure 6, and the aspect ratio of the α-Mg phase is shown in Figure 9. The diameter of the wire is D, and the average crystal grain size of the α-Mg phase in the cross section of the wire is d. In this case, it is conceivable that d/D is set to 1/100 or less (preferably 1/300 or less, more preferably 1/500 or less).

FIG. 11 shows the particle size distribution measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 5, Sample 6, Sample 7, and Sample 8 according to Example 2. This is an organizational photo.

Sample 5 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified product, and its alloy composition is AMX602. It is. AMX602 is, for example, 91.70Mg-6.0Al-0.3Mn-2.0Ca (wt%) or 93.14Mg-5.49Al-0.13Mn-1.23Ca (at%), but each element has There is a wide range of content. Sample 6 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base material wire of Sample 5 to multiple drawing operations and heat treatment. Sample 7 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting Sample 6 to drawing and heat treatment multiple times. Sample 8 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting Sample 7 to drawing and heat treatment multiple times.

The method for manufacturing sample 5 is similar to the method for manufacturing sample 1.
The method for manufacturing sample 6 is similar to the method for manufacturing sample 2.
The method for manufacturing sample 7 is similar to the method for manufacturing sample 3.
The method for manufacturing sample 8 is similar to the method for manufacturing sample 4.

FIG. 12 shows the particle size distribution measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 9, Sample 10, Sample 11, and Sample 12 according to Example 2. This is an organizational photo.

Sample 9 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified product, and its alloy composition is ASTM The symbol is AZ91D. AZ91D is, for example, 90Mg-9Al-0.7Zn-0.3Mn (wt%) or 91.37Mg-8.23Al-0.26Zn-0.13Mn (at%), but the content of each element varies. There is a range. Sample 10 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base material wire of Sample 9 to multiple drawing operations and heat treatment. Sample 11 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting sample 10 to drawing and heat treatment multiple times. Sample 12 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting sample 11 to drawing and heat treatment multiple times.

The manufacturing method of Sample 9 is similar to that of Sample 1.
The method for manufacturing sample 10 is similar to the method for manufacturing sample 2.
The method for manufacturing sample 11 is similar to the method for manufacturing sample 3.
The method for manufacturing sample 12 is similar to the method for manufacturing sample 4.

FIG. 13 shows the particle size distribution measured by EBSD in a cross section (cross section) cut perpendicular to the longitudinal direction of the wire of Sample 13, Sample 14, Sample 15, and Sample 16 according to Example 2. This is an organizational photo.

Sample 13 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified product, and its alloy composition is Mg. _96.75 -Zn _0.85 -Y _2.05 -Al _0.35 . Sample 14 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base material wire of Sample 13 to multiple drawing operations and heat treatment. Sample 15 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting sample 14 to drawing and heat treatment multiple times. Sample 16 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting sample 15 to drawing and heat treatment multiple times.

The method for manufacturing sample 13 is similar to the method for manufacturing sample 1.
The method for manufacturing sample 14 is similar to the method for manufacturing sample 2.
The method for manufacturing sample 15 is similar to the method for manufacturing sample 3.
The method for manufacturing sample 16 is similar to the method for manufacturing sample 4.

FIG. 14 shows cross sections (cross sections) cut perpendicular to the longitudinal direction of the wires of Sample 17, Sample 18, Sample 19, Sample 20, Sample 25, and Sample 26 according to Example 2, when measured by EBSD. Fig. 2 is a microstructure photograph showing the particle size distribution of .

Sample 17 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified product, and its alloy composition is ASTM The symbol is WE43B. WE43B is, for example, 91.65Mg-2.25Y-1.9RE-0.2Zr (wt%), but the content of each element varies. Sample 18 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base material wire of Sample 17 to multiple drawing operations and heat treatment. Sample 19 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting sample 18 to drawing and heat treatment multiple times. Sample 20 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting sample 19 to drawing and heat treatment multiple times. Sample 25 is a magnesium alloy wire with a wire diameter of 0.05 mm obtained by further subjecting sample 20 to drawing and heat treatment multiple times. Sample 26 is a magnesium alloy wire with a wire diameter of 0.03 mm obtained by further subjecting sample 25 to drawing and heat treatment multiple times.

The method for manufacturing sample 17 is similar to the method for manufacturing sample 1.
The method for manufacturing sample 18 is similar to the method for manufacturing sample 2.
The method for manufacturing sample 19 is similar to the method for manufacturing sample 3.
The method for manufacturing sample 20 is similar to the method for manufacturing sample 4.
The method for manufacturing sample 25 is similar to the method for manufacturing sample 5.

The method for producing sample 26 is as follows.
Temperature during drawing of magnesium alloy base wire: 225℃
Drawing speed: 1.0 to 5.0 m/min Heat treatment temperature: 350°C
Heat treatment time: 10 minutes Heat treatment frequency: Performed once for 12 or more processing steps Die material: Diamond die used Die temperature: 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 26: 0.03 mm

FIG. 15 shows cross sections (cross sections) taken perpendicular to the longitudinal direction of the wires of Sample 21, Sample 22, Sample 23, Sample 24, Sample 27, and Sample 28 according to Example 2, when measured by EBSD. Fig. 2 is a microstructure photograph showing the particle size distribution of .

Sample 21 is a magnesium alloy base material wire obtained by solidifying and molding powder, flakes, ribbons, or thin wires produced by the RS-P/M method, and extruding the solidified product, and its alloy composition is Mg. _96.6 -Zn _0.85 -Y _2.05 -Al _0.35 -Ca _0.15 . Sample 22 is a magnesium alloy wire with a wire diameter of 1.0 mm obtained by subjecting the magnesium alloy base wire of sample 21 to multiple drawing operations and heat treatment. Sample 23 is a magnesium alloy wire with a wire diameter of 0.5 mm obtained by further subjecting sample 22 to drawing and heat treatment multiple times. Sample 24 is a magnesium alloy wire with a wire diameter of 0.1 mm obtained by further subjecting sample 23 to drawing and heat treatment multiple times. Sample 27 is a magnesium alloy wire with a wire diameter of 0.05 mm obtained by further subjecting sample 24 to drawing and heat treatment multiple times. Sample 28 is a magnesium alloy wire with a wire diameter of 0.03 mm obtained by further subjecting sample 27 to drawing and heat treatment multiple times.

The method for manufacturing sample 21 is the same as the method for manufacturing sample 1.
The method for manufacturing sample 22 is similar to the method for manufacturing sample 2.
The method for manufacturing sample 23 is similar to the method for manufacturing sample 3.
The method for manufacturing sample 24 is similar to the method for manufacturing sample 4.
The method for manufacturing sample 27 is similar to the method for manufacturing sample 5.

The method for producing sample 28 is as follows.
Temperature during drawing of magnesium alloy base wire: 225℃
Drawing speed: 1.0 to 5.0 m/min Heat treatment temperature: 350°C
Heat treatment time: 10 minutes Heat treatment frequency: Performed once for 12 or more processing steps Die material: Diamond die used Die temperature: 225℃
Die lubricant: Edible oil Drawing direction: Two directions Wire diameter of sample 26: 0.03 mm

FIG. 16 is a diagram showing the grain size distribution shown in FIG. 11 in terms of the relationship between crystal grain sizes and their ratios. FIG. 17 is a diagram showing the grain size distribution shown in FIG. 12 in terms of the relationship between crystal grain sizes and their ratios. FIG. 18 is a diagram showing the grain size distribution shown in FIG. 13 in terms of the relationship between crystal grain sizes and their ratios. FIG. 19 is a diagram showing the grain size distribution shown in FIG. 14 in terms of the relationship between crystal grain sizes and their ratios. FIG. 20 is a diagram showing the grain size distribution shown in FIG. 15 in terms of the relationship between crystal grain sizes and their ratios.

FIG. 21 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 5 to 8. FIG. 22 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 9 to 12. FIG. 23 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 13 to 16. FIG. 24 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 17 to 20, 25, and 26. FIG. 25 is a diagram showing the average crystal grain size of the α-Mg phase in the cross section of each of Samples 21 to 24, 27, and 28.

FIG. 26 is a photograph of the structure observed in a cross section (longitudinal cross section) cut in the longitudinal direction of the wire of each of Samples 13 to 16. FIG. 27 is a photograph of the structure observed in a cross section (vertical cross section) cut in the longitudinal direction of the wire of each of Samples 21 to 24, 27, and 28.

FIG. 28 is a diagram showing the average crystal grain size (structure length) of the α-Mg phase in the longitudinal cross section of Samples 13 to 16, 21 to 24, 27, and 28. FIG. 29 is a diagram showing the aspect ratios of the α-Mg phase crystal grains of Samples 13 to 16, 21 to 24, 27, and 28.

The method for measuring the average crystal grain size d of the α-Mg phase in the cross sections shown in FIGS. 21 to 25 is the same as in Example 1.
The method for measuring the structure length (average grain size L) shown in FIG. 28 is the same as in Example 1.

FIG. 30 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 5 to 8. FIG. 31 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 9 to 12. FIG. 32 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 13 to 16. FIG. 33 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 17 to 20, 25, and 26. FIG. 34 is a diagram showing the results of measuring the 0.2% yield strength of each of Samples 21 to 24, 27, and 28.

As shown in FIG. 34, the wire of sample 21 has a 0.2% proof stress of 472.1 MPa, the wire of sample 22 has a 0.2% proof stress of 492.3 MPa, and the wire of sample 23 has a 0.2% proof stress of 472.1 MPa. The wire of sample 24 has a 0.2% yield strength of .3 MPa, the wire of sample 27 has a 0.2% yield strength of 514.6 MPa, and the wire of sample 28 has a 0.2% yield strength of 514.6 MPa. The wire has a 0.2% yield strength of 534.3 MPa.

The reason why the magnesium alloy wire can have such high strength is that the average crystal grain size of the α-Mg phase is made small as shown in Figures 21 to 25, and the aspect ratio of the α-Mg phase is reduced as shown in Figures 21 to 25. 29, the diameter of the wire is D, and α of the cross section of the wire is - When the average crystal grain size of the Mg phase is d, d/D is 1/100 or less (preferably 1.15/300 or less, more preferably 1.9/500 or less, still more preferably 1/300 or less) It is possible that this was the case.

11... Magnesium alloy base material wire 12... Magnesium alloy wire or magnesium alloy base material wire 13... Dice D... Wire diameter of magnesium alloy wire d3... Wire diameter of magnesium alloy base material wire

Claims (14)

In a magnesium alloy wire containing 80 atomic % or more of Mg and having an α-Mg phase,
The wire diameter of the wire is D, the average crystal grain size of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire is L, and it was observed in a cross section cut perpendicular to the longitudinal direction. A magnesium alloy wire that satisfies the following (Formula 41), (Formula 42), and (Formula 43), where d is the average crystal grain size of the α-Mg phase.
(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1μm
(Formula 43) 10≦L/d In claim 1,
A magnesium alloy wire, wherein the D and d satisfy the following (Formula 44).
(Formula 44) d/D≦1/100 In claim 1 or 2,
The magnesium alloys include Mg-Zn-Y alloy, Mg-Zn-Gd alloy, Mg-Zn-(Y-Gd) alloy, Mg-Zn-YX-Z alloy, Mg-Zn-Gd-X-Z. alloy, and Mg-Zn-Y-Gd-X-Z alloy, or pure Mg,
The X is at least one element selected from the group consisting of Al, Ca and Li,
The Z is at least one element selected from the group consisting of rare earth elements, Mn, Si, Zr, Ti, Hf, Nb, Sn, Ag, Sr, Sc, Sb, B, C and Be,
The content of Zn is a atomic %, the content of Y is b atomic %, the content of Gd is b atomic %, the total content of Y and Gd is b atomic %, and the content of X is c A magnesium alloy wire that satisfies the following (Formula 1) to (Formula 6), where the content of Z is d at %.
(Formula 1) 0.1≦a≦3.0
(Formula 2) 0.1≦b≦3.0
(Formula 3) c≦3.0
(Formula 4) d≦1.0
(Formula 5) b≦a+2
(Formula 6) b≧a−1 In claim 1 or 2,
The magnesium alloy has a composition containing x atomic % of Ca, y atomic % of Al, and the balance consisting of Mg,
A magnesium alloy wire characterized in that a and b satisfy the following (Formula 31) to (Formula 33).
(Formula 31) 3≦x≦7
(Formula 32) 4.5≦y≦12
(Formula 33) 1.2≦y/x≦3.0 In claim 4,
A magnesium alloy wire, characterized in that the magnesium alloy contains x1 atomic % of Zn, and x1 satisfies the following (Formula 34).
(Formula 34) 0<x1≦3 In claim 4 or 5,
The magnesium alloy contains x2 atomic % of at least one element selected from the group of Mn, Zr, Si, Sc, Sn, Ag, Cu, Li, Be, Mo, Nb, W, and rare earth elements, and x2 is A magnesium alloy wire characterized by satisfying the following (Formula 35).
(Formula 35) 0<x2≦0.3 In claim 1 or 2,
A magnesium alloy wire, wherein the magnesium alloy is any one of the following alloys (A) to (F).
(A) is a Mg-Al-Mn alloy, and the following (Formula 7) and (Formula 8) are satisfied, assuming that the Al content is e atomic % and the Mn content is f atomic %.
(Formula 7) 2.7≦e≦9.2
(Formula 8) 0.02≦f≦0.07
(B) Mg-Al-Mn-Ca alloy, where the Al content is g atomic%, the Mn content is h atomic%, and the Ca content is i atomic%, the following (Formula 9) ~ ( Formula 11) is satisfied.
(Formula 9) 2.7≦g≦9.2
(Formula 10) 0.02≦h≦0.07
(Formula 11) 0.4≦i≦1.6
(C) is a Mg-Al-Zn alloy, and the following (Formula 12) and (Formula 13) are satisfied, assuming that the Al content is j atomic % and the Zn content is k atomic %.
(Formula 12) 2.7≦j≦8.4
(Formula 13) 0.3≦k≦1.2
(D) Mg-Al-Zn-Ca alloy, where the Al content is 1 atomic %, the Zn content is m atomic %, and the Ca content is n atomic %, the following (Formula 14) to ( Formula 16) is satisfied.
(Formula 14) 2.7≦l≦8.5
(Formula 15) 0.3≦m≦1.2
(Formula 16) 0.4≦n≦1.6
(E) It is a Mg-Nd-Y alloy, and the following (Formula 17) and (Formula 18) are satisfied, assuming that the Nd content is o atomic % and the Y content is p atomic %.
(Formula 17) 0.3≦o≦0.7
(Formula 18) 0.7≦p≦1.4
(F) is a Mg-Al-RE alloy, and the following (Formula 19) and (Formula 20) are satisfied, assuming that the Al content is q atomic % and the RE content is r atomic %.
(Formula 19) 2.2≦q≦4.2
(Formula 20) 0.2≦r≦0.9 In claim 1 or 2,
The magnesium alloy wire has a long-period layered structure phase,
A magnesium alloy wire, wherein the long-period layered structure phase is precipitated within the α-Mg phase. In any one of claims 1 to 8,
A magnesium alloy wire, wherein the wire has a 0.2% yield strength of 400 MPa or more. a step (a) of rapidly solidifying a molten magnesium alloy containing 80 atomic % or more of Mg to produce a plurality of rapidly solidified products;
a step (b) of producing a solidified molded product by hot extruding the plurality of rapidly solidified products;
a step (c) of producing a magnesium alloy base material wire by extruding the solidified molded product;
a step (d) of manufacturing a magnesium alloy wire having an α-Mg phase by subjecting the magnesium alloy base material wire to a plurality of drawing operations;
Equipped with
The cooling rate when rapidly solidifying the molten magnesium alloy is faster than 1000 K/sec,
The temperature of the magnesium alloy base material wire when performing each of the plurality of drawing operations is 150° C. or more and 350° C. or less, and the drawing speed is 0.1 m/min or more and 100 m/min or less,
The wire diameter of the wire is D, the average crystal grain size of the α-Mg phase observed in a cross section cut in the longitudinal direction of the wire is L, and it was observed in a cross section cut perpendicular to the longitudinal direction. A method for manufacturing a magnesium alloy wire, characterized in that the following (Formula 41), (Formula 42) and (Formula 43) are satisfied, where d is the average crystal grain size of the α-Mg phase.
(Formula 41) 5μm≦D≦50μm
(Formula 42) d≦1μm
(Formula 43) 10≦L/d In claim 10,
A method for manufacturing a magnesium alloy wire, characterized in that the above D and the above d satisfy the following (Formula 44).
(Formula 44) d/D≦1/100 In claim 10 or 11,
A step of heat-treating the magnesium alloy base material wire after at least one of the plurality of drawing operations,
The temperature of the heat treatment is at least 50 °C higher than the temperature of the magnesium alloy base material wire immediately after the drawing process immediately before the heat treatment and at most 400 °C,
A method for manufacturing a magnesium alloy wire, wherein the heat treatment time is 10 seconds or more and 12 hours or less . In any one of claims 10 to 12,
A method for manufacturing a magnesium alloy wire, characterized in that the magnesium alloy wire obtained in step (d) has a 0.2% yield strength of 400 MPa or more. In any one of claims 10 to 13,
A method for manufacturing a magnesium alloy wire, characterized in that the temperature of a die used when performing each of the plurality of drawing operations is set at 200° C. or more and 300° C. or less.

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