WO2010044320A1 - Magnesium alloy and process for production thereof - Google Patents

Magnesium alloy and process for production thereof Download PDF

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Publication number
WO2010044320A1
WO2010044320A1 PCT/JP2009/065701 JP2009065701W WO2010044320A1 WO 2010044320 A1 WO2010044320 A1 WO 2010044320A1 JP 2009065701 W JP2009065701 W JP 2009065701W WO 2010044320 A1 WO2010044320 A1 WO 2010044320A1
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phase
alloy
magnesium alloy
αmg
long
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PCT/JP2009/065701
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French (fr)
Japanese (ja)
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能人 河村
雅史 野田
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国立大学法人 熊本大学
財団法人くまもとテクノ産業財団
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Priority claimed from JP2008265830A external-priority patent/JP2010095741A/en
Priority claimed from JP2008270139A external-priority patent/JP2010095787A/en
Application filed by 国立大学法人 熊本大学, 財団法人くまもとテクノ産業財団 filed Critical 国立大学法人 熊本大学
Publication of WO2010044320A1 publication Critical patent/WO2010044320A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/06—Alloys based on magnesium with a rare earth metal as the next major constituent

Definitions

  • the present invention relates to a magnesium alloy and a method for producing the same. Specifically, the present invention relates to a magnesium alloy having high strength and high ductility, and a method for producing the same.
  • magnesium alloys have the lowest density, light weight, and high strength among the alloys in practical use, so they are being applied to electrical housings, automobile wheels, suspension parts, engine parts, etc. It has been.
  • high mechanical properties are required for parts related to automobiles, and as a magnesium alloy to which elements such as Gd and Zn are added, materials of specific forms are manufactured by the single roll method and rapid solidification method. (For example, refer to Patent Document 1 and Patent Document 2).
  • a conventional magnesium alloy having a long-period laminated structure phase has a tensile strength of about 300 MPa but has an elongation of less than 10%.
  • a commercially available AZ-based magnesium alloy can achieve an elongation of about 15% by annealing at 300 ° C. for about 1 hour, the tensile strength was about 150 MPa.
  • the present invention was devised in view of the above points, and provides a magnesium alloy having excellent tensile strength and good ductility, and can obtain such a magnesium alloy, sufficiently corresponding to actual production.
  • An object of the present invention is to provide a method for producing a magnesium alloy that can be used.
  • the magnesium alloy of the present invention is a magnesium alloy composed of an Mg—Zn—Y-based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities.
  • the alloy structure of the Mg—Zn—Y alloy has an ⁇ Mg phase and a long-period laminate structure phase, and at least a part of the long-period laminate structure phase exists in a lamellar form with the ⁇ Mg phase.
  • At least a part of the lamellar tissue is curved or bent, and further, a discontinuous interface between the ⁇ Mg phase and the long-period laminate structure phase is formed in the curved or bent portion, or the curved or bent Grain boundaries between the ⁇ Mg phase and the long-period stacked structure phase are formed in the bent portion.
  • the alloy structure of the Mg—Zn—Y alloy has an ⁇ Mg phase and a long-period stacked structure phase (hereinafter referred to as “LPSO: Long Period Stacking Order”), and at least a part of the LPSO. It exists in a lamellar form with the ⁇ Mg phase, and at least a part of the lamellar structure is curved or bent, and further, the discontinuous interface (grain boundary) between the ⁇ Mg phase and LPSO in the curved or bent part. Is formed, or a grain boundary of ⁇ Mg phase and LPSO is formed in a curved or bent portion, whereby excellent tensile strength and good ductility can be realized.
  • LPSO Long Period Stacking Order
  • a discontinuous interface (grain boundary) between the ⁇ Mg phase and LPSO is formed in the curved or bent portion.
  • the curved or bent structure of LPSO forms a linear LPSO structure
  • the grain boundary between the ⁇ Mg phase and the LPSO at the curved or bent portion is a stable structure, excellent tensile strength and good ductility can be realized.
  • the magnesium alloy of the present invention is a magnesium alloy composed of an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities.
  • the alloy structure of the Y-based alloy has a needle-like or plate-like long-period laminated structure phase.
  • an Mg—Zn—Y alloy containing Zn and Y as essential components and the balance consisting of Mg and inevitable impurities is cast.
  • a heat treatment step for performing a heat treatment wherein the heat treatment step is performed in a temperature range of 350 ° C. to 500 ° C. and in a time range of 0.5 hours to 10 hours. .
  • FIG. 5 (a) shows the relationship between heat treatment temperature and mechanical properties (tensile strength, 0.2% proof stress and elongation) when Mg 97 Zn 1 Y 2 alloy is annealed for 1 hour
  • FIG. 5 (b) shows the relationship between the heat treatment temperature and mechanical properties (tensile strength, 0.2% proof stress and elongation) in the case where the Mg 96 Zn 2 Y 2 alloy is annealed for 1 hour.
  • an elongation of approximately 10% or more can be obtained while achieving a tensile strength of approximately 300 MPa or higher at a heat treatment temperature of 350 ° C. or higher. Is performed at a temperature of 350 ° C. or higher.
  • symbol a indicates tensile strength
  • symbol b indicates 0.2% proof stress
  • symbol c indicates elongation.
  • the reason why the heat treatment step is performed at a temperature of 500 ° C. or less is that if it exceeds 500 ° C., the melting point of the magnesium alloy is approached, and the heat treatment temperature is limited to 500 ° C. or less in consideration of actual production.
  • the magnesium phase having a 2H structure contained in the long-period laminated structure phase disappears and a long-period laminated structure phase that is a stable structure appears.
  • a tensile strength of 300 MPa or more can be realized, and an elongation of about 12% or more can be realized.
  • the alloy structure has an ⁇ Mg phase and LPSO.
  • the LPSO is present in a lamellar form with the ⁇ Mg phase, and at least a part of the tissue present in the lamellar form is curved or bent, and the ⁇ Mg phase and the LPSO are further bent or bent.
  • Mg—Zn—Y having a discontinuous interface (grain boundary), ⁇ Mg phase and LPSO grain boundary formed in a curved or bent portion, or needle-like or plate-like LPSO phase
  • a magnesium alloy composed of a base alloy can be obtained.
  • the Mg—Zn—Y alloy having such a structure can achieve excellent tensile strength and good ductility.
  • the heat treatment step is preferably performed at a temperature of 400 ° C. or higher, specifically, within a temperature range of 400 ° C. or higher and 500 ° C. or lower.
  • the heat treatment temperature is 450 ° C. or higher, a needle-like or plate-like long-period laminated structure phase appears, realizing a tensile strength of 300 MPa or more and an elongation of approximately 18% or more. can do. Accordingly, it is more preferable that the heat treatment step is performed at a temperature of 450 ° C. or higher, specifically, a temperature range of 450 ° C. or higher and 500 ° C. or lower.
  • the reason for setting the heat treatment time to 0.5 hours or more is to obtain desired mechanical properties, specifically, to realize a tensile strength of 300 MPa or more and an elongation of 10% or more.
  • the reason for setting the heat treatment time to 10 hours or less is that even if the heat treatment is performed for more than 10 hours, the mechanical properties and the structure do not vary so much.
  • the magnesium alloy of the present invention excellent tensile strength and good ductility can be realized. Moreover, in the manufacturing method of the magnesium alloy of this invention, the magnesium alloy which has the outstanding tensile strength and favorable ductility can be obtained. In particular, in the method for producing a magnesium alloy of the present invention, by combining plastic processing and structure control by heat treatment, restrictions on processing conditions and processing methods are relaxed compared to structure control by plastic processing alone, and it fully supports actual production. can do.
  • FIG. 1 (a) is a micrograph showing the crystal structure of an annealed material of Mg 96 Zn 2 Y 2 at 400 ° C. for 1 hour
  • FIG. 1 (b) is 450 ° C. of Mg 96 Zn 2 Y 2 alloy at 1 ° C
  • FIG. 1 (c) is a photomicrograph showing the crystal structure of the annealed material at 475 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy
  • FIG. ) Is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour.
  • the magnesium alloy of the present invention is an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being composed of Mg and inevitable impurities.
  • Mg 97 Zn 1 Y 2 An explanation will be given by taking an alloy or an Mg 96 Zn 2 Y 2 alloy as an example.
  • the magnesium alloy 1 has LPSO 2 and ⁇ Mg phase 3 in its alloy structure.
  • LPSO and ⁇ Mg phase are present in a lamellar shape, and there is no continuity between LPSO and ⁇ Mg phase at the bending portion of the tissue present in the lamellar shape (region indicated by symbol d in the figure) Discontinuous interfaces (grain boundaries) are formed.
  • 1B to 1D have a needle-like or plate-like LPSO.
  • the magnesium alloy of the present invention has LPSO.
  • LPSO is a precipitate that precipitates in the grain and boundary of the magnesium alloy, and has a structure in which the arrangement of bottom atomic layers in the HCP structure is repeated with a long periodic rule in the bottom normal direction, that is, a long period. A laminated structure. This precipitation of LPSO improves the mechanical properties (tensile strength, 0.2% proof stress and elongation) of the magnesium alloy.
  • the magnesium alloy of the present invention has a discontinuous interface (grain boundary) between LPSO and ⁇ Mg phase at the bent portion of the structure existing in a lamellar shape.
  • the magnesium phase having a 2H structure contained in LPSO disappears, and a new LPSO appears.
  • a kink appears as a clear interface by recovery, thereby discontinuous interface. It is considered that (grain boundaries) are visually recognized.
  • the new LPSO which appears by recovery is a stable structure, the mechanical properties (tensile strength, 0.2% yield strength and elongation) are improved.
  • the magnesium alloy of the present invention has a needle-like or plate-like LPSO.
  • the LPSO has a needle shape or a plate shape
  • the kink band of the LPSO is sharpened and the LPSO is finely dispersed.
  • the mechanical properties of the magnesium alloy tensile strength, 0.2%) Yield strength and elongation
  • FIG. 2 is a flowchart for explaining a method for producing a magnesium alloy to which the present invention is applied.
  • a casting step S1 in the manufacturing method of the magnesium alloy to which the present invention is applied, first, casting is performed by a casting step S1.
  • a casting material containing LPSO and ⁇ -Mg phase is formed by casting a Mg—Zn—Y alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities.
  • the cast material formed by the casting process is an Mg 97 Zn 1 Y 2 alloy and the case of an Mg 96 Zn 2 Y 2 alloy will be described as examples.
  • a plastic working step S2 is performed on the cast material.
  • the plastic processing in this plastic processing step is, for example, extrusion processing, forging processing, rolling processing or drawing processing, and the plastic processed product obtained by plastic processing of the cast material has tensile strength, elongation, 0.2%. The yield strength will be significantly improved.
  • the plastic processed product is subjected to heat treatment (specifically, annealing treatment) within a temperature range of 350 ° C. to 500 ° C. and within a time range of 0.5 hours to 10 hours.
  • heat treatment specifically, annealing treatment
  • the structure is controlled by the heat treatment process so that the crystal grain size of the ⁇ Mg phase becomes 7 ⁇ m to 15 ⁇ m.
  • the crystal grain size of the ⁇ Mg phase becomes 7 ⁇ m to 15 ⁇ m.
  • a crystal grain size of 7 ⁇ m can be obtained by performing heat treatment at 400 ° C. for 1 hour
  • a crystal grain size of 10 ⁇ m can be obtained by performing heat treatment at 500 ° C. for 1 hour.
  • a crystal grain size of 15 ⁇ m can be obtained by performing a heat treatment for 10 hours.
  • the structure of the ⁇ Mg phase crystal grain size is controlled to 7 ⁇ m to 15 ⁇ m in the case of Mg 97 Zn 1 Y 2 alloy by controlling the structure within such a range to obtain a tensile strength of approximately 300 MPa or more. This is because both elongations of approximately 10% or more can be realized (see FIG. 5A).
  • FIG. 3 (a) is a micrograph showing the crystal structure of the extruded material of Mg 97 Zn 1 Y 2 alloy
  • Fig. 3 (b) is an annealing of Mg 97 Zn 1 Y 2 alloy at 300 ° C for 1 hour
  • FIG. 3 (c) is a micrograph showing the crystal structure of the annealed material at 400 ° C. for 1 hour in the Mg 97 Zn 1 Y 2 alloy
  • FIG. 97 Zn 1 Y 2 500 °C alloy is a photomicrograph showing the crystal structure of the annealed material an hour.
  • 3 (a) to 3 (d) the magnesium alloys obtained by the magnesium alloy manufacturing method to which the present invention is applied are shown in FIGS.
  • Alloy 1 has LPSO 2 and ⁇ Mg phase 3 in its alloy structure.
  • the black portions are LPSO, and the granular portions are ⁇ Mg phases.
  • the structure is controlled by the heat treatment process so that the crystal grain size of the ⁇ Mg phase becomes 3 ⁇ m to 10 ⁇ m. Specifically, by performing heat treatment within a temperature range of 350 ° C. or more and 500 ° C. or less and within a time range of 0.5 hours or more and 10 hours or less, the crystal grain size of the ⁇ Mg phase becomes 3 ⁇ m to 10 ⁇ m. To control the organization. As an example, a crystal grain size of 3 ⁇ m can be obtained by performing heat treatment at 400 ° C. for 1 hour, and a crystal grain size of 10 ⁇ m can be obtained by performing heat treatment at 500 ° C. for 1 hour.
  • the structure of the ⁇ Mg phase crystal grain size is controlled to 3 ⁇ m to 10 ⁇ m in the case of the Mg 96 Zn 2 Y 2 alloy, by controlling the structure within such a range, This is because both elongations of approximately 10% or more can be realized (see FIG. 5B).
  • FIG. 3 (e) is a photomicrograph showing the crystal structure of the extruded material of Mg 96 Zn 2 Y 2 alloy
  • FIG. 3 (f) is an annealing of Mg 96 Zn 2 Y 2 alloy at 300 ° C. for 1 hour
  • FIG. 3 (g) is a micrograph showing the crystal structure of the annealed material at 400 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy
  • FIG. 96 Zn 2 Y 2 500 °C alloy is a photomicrograph showing the crystal structure of the annealed material an hour.
  • 3 (e) to 3 (h) the magnesium alloys obtained by the magnesium alloy manufacturing method to which the present invention is applied are shown in FIGS.
  • Alloy 1 has LPSO 2 and ⁇ Mg phase 3 in its alloy structure.
  • the black portions are LPSO, and the granular portions are ⁇ Mg phases.
  • FIG. 4A is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour
  • FIG. 4B is 450 of the Mg 96 Zn 2 Y 2 alloy
  • FIG. 4 (c) is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 1 hour in the Mg 96 Zn 2 Y 2 alloy.
  • intermetallic compound Mg 3 Zn 3 Y 2 is formed.
  • the part indicated by symbol e is the intermetallic compound Mg 3 Zn 3 Y 2 .
  • an Mg 96 Zn 2 Y 2 alloy is used.
  • heat treatment specifically, annealing treatment
  • a temperature of 400 ° C. or higher an elongation of approximately 12% or more can be achieved while achieving a tensile strength of approximately 300 MPa or more.
  • a magnesium alloy can be obtained.
  • heat treatment specifically, annealing treatment
  • a magnesium alloy that can achieve an elongation of approximately 18% or more while achieving a tensile strength of approximately 300 MPa or more. Can be obtained.
  • FIG. 6A is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour. From the micrograph shown in FIG. It turns out that it has precipitated in the grain.
  • FIG. 6B is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 425 ° C. for 1 hour. From the micrograph shown in FIG. It can be clearly seen from FIG.
  • FIG. 6C is a photomicrograph showing the crystal structure of the annealed material at 450 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy. From the micrograph shown in FIG.
  • FIG. 6 (d) is a micrograph showing the crystal structure of the annealed material at 475 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy. From the micrograph shown in FIG. 6 (d), grains of ⁇ Mg phase It can be seen that needle-like or plate-like LPSO grows in the boundary and / or within the grains, and the needle-like or plate-like LPSOs are united with each other. Further, FIG. 6 (e) is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour.
  • the appearing LPSO exhibits a needle-like structure or a plate-like structure, so that the kink band is sharper than the extruded material.
  • LPSO is finely dispersed. Therefore, as described above, it is possible to obtain a magnesium alloy that can achieve an elongation of approximately 18% or more while achieving a tensile strength of approximately 300 MPa or more.
  • FIG. 7A is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 1 hour in the Mg 97 Zn 1 Y 2 alloy
  • FIG. 7B is 500 ° C. in the Mg 97 Zn 1 Y 2 alloy
  • FIG. 7C is a photomicrograph showing the crystal structure of the annealed material for 5 hours
  • FIG. 7C is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 10 hours for the Mg 97 Zn 1 Y 2 alloy.
  • the Mg 97 Zn 1 Y 2 alloy which is a magnesium alloy to which the present invention is applied, has improved thermal stability. It turns out that it is excellent.
  • the recrystallization temperature of the magnesium alloy is about 300 ° C.
  • the crystal grain size grows to increase the elongation. Is improved, but the tensile strength is extremely reduced.
  • the black portions are LPSO and the granular portions are ⁇ Mg phases.
  • FIG. 7 (d) is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour
  • FIG. 7 (e) is a 500 photo of Mg 96 Zn 2 Y 2 alloy
  • FIG. 7 (f) is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 10 hours of the Mg 96 Zn 2 Y 2 alloy.
  • the crystal structure shown in FIG. 7 (d) and the crystal structure shown in FIG. 7 (f) are not greatly different in crystal grain size, and the Mg 96 Zn 2 Y 2 alloy, which is a magnesium alloy to which the present invention is applied, is thermally stable. It turns out that it is excellent in.
  • the black portions are LPSO and the granular portions are ⁇ Mg phases.
  • FIG. 8A is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour.
  • the crystal orientation of LPSO It can be seen that there is no regularity in the orientation of the crystal orientation of the ⁇ Mg phase and the orientation of the crystal orientation is disordered.
  • FIG. 8 (b) is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 at 500 ° C. for 1 hour. In the micrograph shown in FIG.
  • the same LPSO the same LPSO
  • the orientations of the crystal orientations are the same, and the orientation of the crystal orientation in any LPSO is the same as the crystal orientation of any of the adjacent ⁇ Mg phases.
  • the orientation of crystal orientation in any LPSO may be the same as both of the adjacent ⁇ Mg phases.
  • the LPSO appears in the ⁇ Mg phase grain boundaries or in the crystal grains, and may appear in the crystal grain boundaries and crystal grains.
  • Example shown here is an example and does not limit this invention.
  • Example (1) First, as a method for producing a magnesium alloy according to Example (1) of the present invention, Zn is 1 atomic%, Y is 2 atomic%, and the balance is Mg and an inevitable impurity Mg—Zn—Y alloy in an argon gas atmosphere. The melting was performed in the high frequency melting furnace. Next, the heat-dissolved material was cast with a mold to produce an ingot (cast material) of ⁇ 29 mm ⁇ L60 mm.
  • plastic processing is performed under the conditions of an extrusion temperature of 350 ° C., an extrusion ratio of 10 and an extrusion speed of 2.5 mm / s, and then heat treatment (annealing) for 1 hour at a heat treatment temperature of 100 ° C. to 500 ° C. What was done was made.
  • the Mg 97 Zn 1 Y 2 alloy obtained by the magnesium alloy production method of Example (1) of the present invention is approximately 300 MPa when annealed at a temperature of 350 ° C. or higher. While achieving the above tensile strength, it is possible to achieve an elongation of approximately 10% or more. Further, as is apparent from FIG. 5 (a), when the Mg 97 Zn 1 Y 2 alloy obtained by the magnesium alloy production method of Example (1) of the present invention is annealed at a temperature of 400 ° C. or higher, Achieving a tensile strength of approximately 300 MPa or more and an elongation of approximately 12% or more. When annealed at a temperature of 450 ° C. or more, a tensile strength of approximately 300 MPa or more is achieved and an elongation of approximately 18% or more is achieved. be able to.
  • Example (2) In addition, as a manufacturing method of the magnesium alloy of Example (2) of the present invention, Zn is 2 atomic%, Y is 2 atomic%, and the balance is Mg and an inevitable impurity Mg—Zn—Y alloy in an argon gas atmosphere. The melting was performed in the high frequency melting furnace. Next, the heat-dissolved material was cast with a mold to produce an ingot (cast material) of ⁇ 29 mm ⁇ L60 mm.
  • plastic processing is performed under the conditions of an extrusion temperature of 350 ° C., an extrusion ratio of 10 and an extrusion speed of 2.5 mm / s, and then heat treatment (annealing) for 1 hour at a heat treatment temperature of 100 ° C. to 500 ° C. What was done was made.
  • the Mg 96 Zn 2 Y 2 alloy obtained by the magnesium alloy production method of Example (2) of the present invention is approximately 300 MPa when annealed at a temperature of 350 ° C. or higher. While achieving the above tensile strength, it is possible to achieve an elongation of approximately 10% or more. Further, as apparent from FIG. 5 (b), when the Mg 96 Zn 2 Y 2 alloy obtained by the magnesium alloy manufacturing method of Example (2) of the present invention was annealed at a temperature of 400 ° C. or higher, Achieving a tensile strength of approximately 300 MPa or more and an elongation of approximately 12% or more. When annealed at a temperature of 450 ° C. or more, a tensile strength of approximately 300 MPa or more is achieved and an elongation of approximately 18% or more is achieved. be able to.

Abstract

Provided is a magnesium alloy which has excellent tensile strength and excellent ductility.  The magnesium alloy is an Mg-Zn-Y type alloy which contains Zn and Y as the essential components with the balance consisting of Mg and unavoidable impurities and which has an alloy structure containing both an αMg phase and an LPSO phase.  The αMg phase and LPSO phase are present in the form of a lamellar structure, and a part of the lamellar structure is curved or bent.  Further, a discontinuous interface or grain boundary between αMg and LPSO phases is formed in the curved or bent portion.

Description

マグネシウム合金及びその製造方法Magnesium alloy and manufacturing method thereof
　本発明はマグネシウム合金及びその製造方法に関する。詳しくは、高強度であると共に高延性であるマグネシウム合金及びその製造方法に係るものである。 The present invention relates to a magnesium alloy and a method for producing the same. Specifically, the present invention relates to a magnesium alloy having high strength and high ductility, and a method for producing the same.
　一般に、マグネシウム合金は、実用化されている合金の中で最も密度が低く軽量で強度も高いため、電気製品の筐体や、自動車のホイール、足回り部品、エンジン回り部品等への適用が進められている。
　特に、自動車に関連する用途の部品においては、高い機械的特性が要求されるため、ＧｄやＺｎ等の元素を添加したマグネシウム合金として、片ロール法、急速凝固法により特定の形態の材料を製造することが行われている（例えば、特許文献１、特許文献２参照。）。 In general, magnesium alloys have the lowest density, light weight, and high strength among the alloys in practical use, so they are being applied to electrical housings, automobile wheels, suspension parts, engine parts, etc. It has been.
In particular, high mechanical properties are required for parts related to automobiles, and as a magnesium alloy to which elements such as Gd and Zn are added, materials of specific forms are manufactured by the single roll method and rapid solidification method. (For example, refer to Patent Document 1 and Patent Document 2).
　しかし、上記したマグネシウム合金は、特定の製造方法においては高い機械的特性が得られるものの、特定の製造方法を実現するためには特殊な設備が必要であり、しかも、生産性が低いといった問題があり、更には、適用できる部材も限られるといった問題があった。 However, although the above-described magnesium alloy can obtain high mechanical properties in a specific manufacturing method, special equipment is required to realize the specific manufacturing method, and the productivity is low. In addition, there is a problem that applicable members are limited.
　そこで、従来、マグネシウム合金を製造する場合、上記した特許文献１及び特許文献２に記載の様な特殊な設備あるいはプロセスを用いずに、生産性の高い通常の溶解鋳造から塑性加工（押出）を実施しても、実用上有用な機械的特性が得られる技術が提案されている（例えば、特許文献３参照。）。なお、特許文献３に開示されているマグネシウム合金は、高強度が得られることが知られている。 Therefore, conventionally, when producing a magnesium alloy, plastic processing (extrusion) is performed from ordinary melt casting with high productivity without using special equipment or processes as described in Patent Document 1 and Patent Document 2 described above. A technique that can obtain practically useful mechanical characteristics even if implemented is proposed (for example, see Patent Document 3). In addition, it is known that the magnesium alloy currently disclosed by patent document 3 will obtain high intensity | strength.
特開平６－４１７０１号公報JP-A-6-41701 特開２００２－２５６３７０号公報JP 2002-256370 A 特開２００６－９７０３７号公報JP 2006-97037 A
　しかしながら、従来の高強度を示すマグネシウム合金（例えば、特許文献３に記載のマグネシウム合金）は高延性を得ることが難しかった。例えば、従来の長周期積層構造相を有するマグネシウム合金では、３００ＭＰａ程度の引張強度を有しているものの、伸びは１０％未満であった。 However, conventional magnesium alloys exhibiting high strength (for example, the magnesium alloy described in Patent Document 3) have been difficult to obtain high ductility. For example, a conventional magnesium alloy having a long-period laminated structure phase has a tensile strength of about 300 MPa but has an elongation of less than 10%.
　また、市販のＡＺ系マグネシウム合金では３００℃で１時間程度の焼きなましを施すことによって１５％程度の伸びを実現することができるものの、引張強度は１５０ＭＰａ程度であった。 In addition, although a commercially available AZ-based magnesium alloy can achieve an elongation of about 15% by annealing at 300 ° C. for about 1 hour, the tensile strength was about 150 MPa.
　なお、加工条件や加工方法を厳選することによって、塑性加工のみで高強度及び高延性を満足するマグネシウム合金を実現することがあるいは可能であるかもしれない。しかし、限定された加工条件や加工方法によって高強度及び高延性を満足するマグネシウム合金が実現したとしても、こうした限定された製造方法では、実生産に供するマグネシウム合金の製造方法としては充分であるとは言い難いものである。 In addition, by carefully selecting the processing conditions and processing methods, it may be possible or possible to realize a magnesium alloy that satisfies high strength and high ductility only by plastic processing. However, even if a magnesium alloy satisfying high strength and high ductility is realized by limited processing conditions and processing methods, such a limited manufacturing method is sufficient as a manufacturing method of magnesium alloy for actual production. Is hard to say.
　本発明は以上の点に鑑みて創案されたものであって、優れた引張強度と良好な延性を有するマグネシウム合金を提供すると共に、こうしたマグネシウム合金を得ることができ、実生産に充分に対応することが可能なマグネシウム合金の製造方法を提供することを目的とするものである。 The present invention was devised in view of the above points, and provides a magnesium alloy having excellent tensile strength and good ductility, and can obtain such a magnesium alloy, sufficiently corresponding to actual production. An object of the present invention is to provide a method for producing a magnesium alloy that can be used.
　上記の目的を達成するために、本発明のマグネシウム合金は、必須成分としてＺｎとＹとを含有し、残部がＭｇと不可避的不純物からなるＭｇ－Ｚｎ－Ｙ系合金から構成されるマグネシウム合金であって、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、αＭｇ相と長周期積層構造相とを有し、該長周期積層構造相の少なくとも一部が前記αＭｇ相とラメラ状に存在すると共に、該ラメラ状に存在する組織の少なくとも一部が湾曲または屈曲しており、更に、湾曲または屈曲している部分でαＭｇ相と長周期積層構造相の不連続界面が形成され、若しくは、湾曲または屈曲している部分でαＭｇ相と長周期積層構造相の粒界が形成されている。 In order to achieve the above object, the magnesium alloy of the present invention is a magnesium alloy composed of an Mg—Zn—Y-based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities. The alloy structure of the Mg—Zn—Y alloy has an αMg phase and a long-period laminate structure phase, and at least a part of the long-period laminate structure phase exists in a lamellar form with the αMg phase. At least a part of the lamellar tissue is curved or bent, and further, a discontinuous interface between the αMg phase and the long-period laminate structure phase is formed in the curved or bent portion, or the curved or bent Grain boundaries between the αMg phase and the long-period stacked structure phase are formed in the bent portion.
　ここで、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、αＭｇ相と長周期積層構造相（以下、「ＬＰＳＯ：Ｌｏｎｇ　Ｐｅｒｉｏｄ　Ｓｔａｃｋｉｎｇ　Ｏｒｄｅｒ」と称する。）とを有し、ＬＰＳＯの少なくとも一部がαＭｇ相とラメラ状に存在すると共に、ラメラ状に存在する組織の少なくとも一部が湾曲または屈曲しており、更に、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの不連続界面（粒界）が形成され、若しくは、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの粒界が形成されていることによって、優れた引張強度と良好な延性を実現することができる。
　即ち、ＬＰＳＯ中に含まれている２Ｈ構造を有するマグネシウム相が消失して新たなＬＰＳＯが現出する結果として、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの不連続界面（粒界）が形成され（例えば、５００℃の焼きなまし材においては、ＬＰＳＯの湾曲または屈曲している組織が直線的なＬＰＳＯ組織を形成する）、若しくは、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの粒界が形成されることとなるのであるが、現出する新たなＬＰＳＯが安定組織であるが故に、優れた引張強度と良好な延性が実現することができるのである。 Here, the alloy structure of the Mg—Zn—Y alloy has an αMg phase and a long-period stacked structure phase (hereinafter referred to as “LPSO: Long Period Stacking Order”), and at least a part of the LPSO. It exists in a lamellar form with the αMg phase, and at least a part of the lamellar structure is curved or bent, and further, the discontinuous interface (grain boundary) between the αMg phase and LPSO in the curved or bent part. Is formed, or a grain boundary of αMg phase and LPSO is formed in a curved or bent portion, whereby excellent tensile strength and good ductility can be realized.
That is, as a result of disappearance of the magnesium phase having a 2H structure contained in LPSO and appearance of new LPSO, a discontinuous interface (grain boundary) between the αMg phase and LPSO is formed in the curved or bent portion. (For example, in an annealed material at 500 ° C., the curved or bent structure of LPSO forms a linear LPSO structure), or the grain boundary between the αMg phase and the LPSO at the curved or bent portion However, since the new LPSO that appears is a stable structure, excellent tensile strength and good ductility can be realized.
　また、本発明のマグネシウム合金は、必須成分としてＺｎとＹとを含有し、残部がＭｇと不可避的不純物からなるＭｇ－Ｚｎ－Ｙ系合金から構成されるマグネシウム合金であって、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、針状若しくは板状の長周期積層構造相を有する。 The magnesium alloy of the present invention is a magnesium alloy composed of an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities. The alloy structure of the Y-based alloy has a needle-like or plate-like long-period laminated structure phase.
　ここで、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、針状若しくは板状のＬＰＳＯを有することによって、優れた引張強度と良好な延性を実現することができる。
　即ち、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、針状若しくは板状のＬＰＳＯを有するということは、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中にラメラ状に存在していたＬＰＳＯが針状若しくは板状に変化したということであり、ＬＰＳＯが有するキンク帯の先鋭化が生じると共にＬＰＳＯが微細分散したことを意味するものである。従って、Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、針状若しくは板状のＬＰＳＯを有することによって、上述の通り、優れた引張強度と良好な延性を実現することができるのである。 Here, excellent tensile strength and good ductility can be realized by having acicular or plate-like LPSO in the alloy structure of the Mg—Zn—Y alloy.
In other words, the fact that the alloy structure of the Mg—Zn—Y alloy has a needle-like or plate-like LPSO means that the LPSO that existed in a lamellar form in the alloy structure of the Mg—Zn—Y alloy This means that the kink band of LPSO is sharpened and LPSO is finely dispersed. Therefore, by having the needle-like or plate-like LPSO in the alloy structure of the Mg—Zn—Y alloy, it is possible to realize excellent tensile strength and good ductility as described above.
　また、上記の目的を達成するために、本発明のマグネシウム合金の製造方法では、必須成分としてＺｎとＹを含有し、残部がＭｇと不可避的不純物とからなるＭｇ－Ｚｎ－Ｙ系合金を鋳造して、長周期積層構造相とαＭｇ相とを含む鋳造材を形成する鋳造工程と、前記鋳造材に塑性加工を行う塑性加工工程と、該塑性加工工程により塑性加工を施した前記鋳造材に熱処理を施す熱処理工程とを備えるマグネシウム合金の製造方法であって、前記熱処理工程は、３５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で行う。 In order to achieve the above object, in the method for producing a magnesium alloy of the present invention, an Mg—Zn—Y alloy containing Zn and Y as essential components and the balance consisting of Mg and inevitable impurities is cast. A casting process for forming a cast material containing a long-period laminated structure phase and an αMg phase, a plastic working process for performing plastic working on the cast material, and the casting material subjected to plastic working by the plastic working process. And a heat treatment step for performing a heat treatment, wherein the heat treatment step is performed in a temperature range of 350 ° C. to 500 ° C. and in a time range of 0.5 hours to 10 hours. .
　ここで、熱処理工程を３５０℃以上の温度で行うのは、概ね１０％以上の伸びを得るためである。図５（ａ）にＭｇ９７Ｚｎ１Ｙ２合金を１時間焼きなました場合における熱処理温度と機械的特性（引張強度、０．２％耐力及び伸び）との関係を示し、図５（ｂ）にＭｇ９６Ｚｎ２Ｙ２合金を１時間焼きなました場合における熱処理温度と機械的特性（引張強度、０．２％耐力及び伸び）との関係を示す。これら図５（ａ）及び図５（ｂ）から明らかな様に、熱処理温度が３５０℃以上で概ね３００ＭＰａ以上の引張強度を実現しつつ概ね１０％以上の伸びを得ることができるため、熱処理工程を３５０℃以上の温度で行うこととしている。なお、図５（ａ）及び図５（ｂ）中符号ａは引張強度を示し、符号ｂは０．２％耐力を示し、符号ｃは伸びを示している。 Here, the reason why the heat treatment step is performed at a temperature of 350 ° C. or higher is to obtain an elongation of approximately 10% or more. FIG. 5 (a) shows the relationship between heat treatment temperature and mechanical properties (tensile strength, 0.2% proof stress and elongation) when Mg 97 Zn 1 Y 2 alloy is annealed for 1 hour, and FIG. 5 (b). The relationship between the heat treatment temperature and mechanical properties (tensile strength, 0.2% proof stress and elongation) in the case where the Mg 96 Zn 2 Y 2 alloy is annealed for 1 hour is shown. As apparent from FIGS. 5 (a) and 5 (b), an elongation of approximately 10% or more can be obtained while achieving a tensile strength of approximately 300 MPa or higher at a heat treatment temperature of 350 ° C. or higher. Is performed at a temperature of 350 ° C. or higher. In FIGS. 5A and 5B, symbol a indicates tensile strength, symbol b indicates 0.2% proof stress, and symbol c indicates elongation.
　また、熱処理工程を５００℃以下の温度で行うのは、５００℃を超えるとマグネシウム合金の融点に近づいてしまうためであり、実生産を考慮して熱処理温度を５００℃以下に限定している。 Moreover, the reason why the heat treatment step is performed at a temperature of 500 ° C. or less is that if it exceeds 500 ° C., the melting point of the magnesium alloy is approached, and the heat treatment temperature is limited to 500 ° C. or less in consideration of actual production.
　なお、熱処理温度を４００℃以上の温度で行った場合には、長周期積層構造相中に含まれている２Ｈ構造を有するマグネシウム相が消失して安定組織である長周期積層構造相が現出し、３００ＭＰａ以上の引張強度を実現すると共に概ね１２％以上の伸びをも実現することができる。
　詳しくは、熱処理工程を、４００℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以内の時間範囲内で行うことによって、合金組織中に、αＭｇ相とＬＰＳＯとを有し、ＬＰＳＯの少なくとも一部がαＭｇ相とラメラ状に存在すると共に、ラメラ状に存在する組織の少なくとも一部が湾曲または屈曲しており、更に、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの不連続界面（粒界）が形成され、若しくは、湾曲または屈曲している部分でαＭｇ相とＬＰＳＯの粒界が形成され、若しくは、針状あるいは板状のＬＰＳＯ相を有するＭｇ－Ｚｎ－Ｙ系合金から構成されるマグネシウム合金を得ることができる。そして、この様な組織をＭｇ－Ｚｎ－Ｙ系合金が有することによって、優れた引張強度と良好な延性を実現することができるのである。
　従って、熱処理工程は４００℃以上の温度、詳しくは、４００℃以上５００℃以下の温度範囲内で行うのが好ましい。 When the heat treatment temperature is 400 ° C. or higher, the magnesium phase having a 2H structure contained in the long-period laminated structure phase disappears and a long-period laminated structure phase that is a stable structure appears. In addition, a tensile strength of 300 MPa or more can be realized, and an elongation of about 12% or more can be realized.
Specifically, by performing the heat treatment step within a temperature range of 400 ° C. or more and 500 ° C. or less and within a time range of 0.5 hours or more and 10 hours or less, the alloy structure has an αMg phase and LPSO. In addition, at least a part of the LPSO is present in a lamellar form with the αMg phase, and at least a part of the tissue present in the lamellar form is curved or bent, and the αMg phase and the LPSO are further bent or bent. Mg—Zn—Y having a discontinuous interface (grain boundary), αMg phase and LPSO grain boundary formed in a curved or bent portion, or needle-like or plate-like LPSO phase A magnesium alloy composed of a base alloy can be obtained. The Mg—Zn—Y alloy having such a structure can achieve excellent tensile strength and good ductility.
Accordingly, the heat treatment step is preferably performed at a temperature of 400 ° C. or higher, specifically, within a temperature range of 400 ° C. or higher and 500 ° C. or lower.
　更に、熱処理温度を４５０℃以上の温度で行った場合には、針状若しくは板状の長周期積層構造相が現出し、３００ＭＰａ以上の引張強度を実現すると共に概ね１８％以上の伸びをも実現することができる。従って、熱処理工程は４５０℃以上の温度、詳しくは、４５０℃以上５００℃以下の温度範囲内で行うのがより一層好ましい。 Furthermore, when the heat treatment temperature is 450 ° C. or higher, a needle-like or plate-like long-period laminated structure phase appears, realizing a tensile strength of 300 MPa or more and an elongation of approximately 18% or more. can do. Accordingly, it is more preferable that the heat treatment step is performed at a temperature of 450 ° C. or higher, specifically, a temperature range of 450 ° C. or higher and 500 ° C. or lower.
　また、熱処理時間を０．５時間以上としているのは、所望の機械的性質を得るためであり、具体的には、３００ＭＰａ以上の引張強度と１０％以上の伸びを実現するためである。 Further, the reason for setting the heat treatment time to 0.5 hours or more is to obtain desired mechanical properties, specifically, to realize a tensile strength of 300 MPa or more and an elongation of 10% or more.
　また、熱処理時間を１０時間以下としているのは、１０時間を超えて熱処理を行ったとしても、機械的性質や組織がそれほど大きな違いを生じないためである。 Moreover, the reason for setting the heat treatment time to 10 hours or less is that even if the heat treatment is performed for more than 10 hours, the mechanical properties and the structure do not vary so much.
　本発明のマグネシウム合金では、優れた引張強度と良好な延性を実現することができる。また、本発明のマグネシウム合金の製造方法では、優れた引張強度と良好な延性を有するマグネシウム合金を得ることができる。特に、本発明のマグネシウム合金の製造方法では、塑性加工と熱処理による組織制御を組み合わせることによって、塑性加工のみによる組織制御と比較すると加工条件や加工方法の制限が緩和され、実生産に充分に対応することができる。 In the magnesium alloy of the present invention, excellent tensile strength and good ductility can be realized. Moreover, in the manufacturing method of the magnesium alloy of this invention, the magnesium alloy which has the outstanding tensile strength and favorable ductility can be obtained. In particular, in the method for producing a magnesium alloy of the present invention, by combining plastic processing and structure control by heat treatment, restrictions on processing conditions and processing methods are relaxed compared to structure control by plastic processing alone, and it fully supports actual production. can do.
結晶組織を示す顕微鏡写真（１）である。It is a microscope picture (1) which shows a crystal structure. 本発明を適用したマグネシウム合金の製造方法を説明するためのフローチャートである。It is a flowchart for demonstrating the manufacturing method of the magnesium alloy to which this invention is applied. 結晶組織を示す顕微鏡写真（２）である。It is a microscope picture (2) which shows a crystal structure. 金属間化合物Ｍｇ３Ｚｎ３Ｙ２を示す顕微鏡写真である。Is a photomicrograph showing the intermetallic compound Mg 3 Zn 3 Y 2. 焼きなまし温度と、引張強度、０．２％耐力及び伸びとの関係を示すグラフである。It is a graph which shows the relationship between annealing temperature, tensile strength, 0.2% yield strength, and elongation. 結晶組織を示す顕微鏡写真（３）である。It is a microscope picture (3) which shows a crystal structure. 結晶組織を示す顕微鏡写真（４）である。It is a microscope picture (4) which shows a crystal structure. 結晶組織を示す顕微鏡写真（５）である。It is a microscope picture (5) which shows a crystal structure.
　以下、本発明の実施の形態について図面を参酌しながら説明し、本発明の理解に供する。
　図１（ａ）はＭｇ９６Ｚｎ２Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図１（ｂ）はＭｇ９６Ｚｎ２Ｙ２合金の４５０℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図１（ｃ）はＭｇ９６Ｚｎ２Ｙ２合金の４７５℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図１（ｄ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings to provide an understanding of the present invention.
FIG. 1 (a) is a micrograph showing the crystal structure of an annealed material of Mg 96 Zn 2 Y 2 at 400 ° C. for 1 hour, and FIG. 1 (b) is 450 ° C. of Mg 96 Zn 2 Y 2 alloy at 1 ° C. FIG. 1 (c) is a photomicrograph showing the crystal structure of the annealed material at 475 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy, and FIG. ) Is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour.
　ここで、本発明のマグネシウム合金は、必須成分としてＺｎ及びＹを含有し、残部がＭｇと不可避的不純物とからなるＭｇ－Ｚｎ－Ｙ系合金であるが、以下では、Ｍｇ９７Ｚｎ１Ｙ２合金やＭｇ９６Ｚｎ２Ｙ２合金を例に挙げて説明を行う。なお、図１（ａ）～図１（ｄ）に示す様に、マグネシウム合金１は、その合金組織中に、ＬＰＳＯ２とαＭｇ相３とを有している。 Here, the magnesium alloy of the present invention is an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being composed of Mg and inevitable impurities. In the following, Mg 97 Zn 1 Y 2 An explanation will be given by taking an alloy or an Mg 96 Zn 2 Y 2 alloy as an example. As shown in FIGS. 1A to 1D, the magnesium alloy 1 has LPSO 2 and αMg phase 3 in its alloy structure.
　また、図１（ａ）では、ＬＰＳＯとαＭｇ相とがラメラ状に存在し、ラメラ状に存在する組織の屈曲部（図中符号ｄで示す領域）でＬＰＳＯとαＭｇ相に連続性が無く、不連続界面（粒界）を形成している。なお、図１（ｂ）～図１（ｄ）では、針状若しくは板状のＬＰＳＯを有している。 Further, in FIG. 1 (a), LPSO and αMg phase are present in a lamellar shape, and there is no continuity between LPSO and αMg phase at the bending portion of the tissue present in the lamellar shape (region indicated by symbol d in the figure) Discontinuous interfaces (grain boundaries) are formed. 1B to 1D have a needle-like or plate-like LPSO.
［ＬＰＳＯについて］
　先ず、本発明のマグネシウム合金は、ＬＰＳＯを有している。
　ここで、ＬＰＳＯとは、マグネシウム合金の粒内及び粒界に析出する析出物であって、ＨＣＰ構造における底面原子層の並びが底面法線方向に長周期規則をもって繰り返される構造、即ち、長周期積層構造をいう。このＬＰＳＯの析出によって、マグネシウム合金の機械的特性（引張強度、０．２％耐力及び伸び）が向上することとなる。 [About LPSO]
First, the magnesium alloy of the present invention has LPSO.
Here, LPSO is a precipitate that precipitates in the grain and boundary of the magnesium alloy, and has a structure in which the arrangement of bottom atomic layers in the HCP structure is repeated with a long periodic rule in the bottom normal direction, that is, a long period. A laminated structure. This precipitation of LPSO improves the mechanical properties (tensile strength, 0.2% proof stress and elongation) of the magnesium alloy.
［不連続界面（粒界）について］
　また、図１（ａ）からも明らかな様に、本発明のマグネシウム合金は、ラメラ状に存在する組織の屈曲部でＬＰＳＯとαＭｇ相の不連続界面（粒界）を有している。
　ここで、ＬＰＳＯ中に含まれている２Ｈ構造を有するマグネシウム相が消失し、新たなＬＰＳＯが現出することによって、換言すると、回復によってキンクが明瞭な界面として現出することで、不連続界面（粒界）が視認されているものであると考えられる。そして、回復によって現出する新たなＬＰＳＯが安定組織であるが故に、機械的特性（引張強さ、０．２％耐力及び伸び）が向上することとなる。 [Discontinuous interface (grain boundary)]
As is clear from FIG. 1 (a), the magnesium alloy of the present invention has a discontinuous interface (grain boundary) between LPSO and αMg phase at the bent portion of the structure existing in a lamellar shape.
Here, the magnesium phase having a 2H structure contained in LPSO disappears, and a new LPSO appears. In other words, a kink appears as a clear interface by recovery, thereby discontinuous interface. It is considered that (grain boundaries) are visually recognized. And since the new LPSO which appears by recovery is a stable structure, the mechanical properties (tensile strength, 0.2% yield strength and elongation) are improved.
［針状若しくは板状のＬＰＳＯについて］
　更に、図１（ｂ）～図１（ｄ）からも明らかな様に、本発明のマグネシウム合金は、針状若しくは板状のＬＰＳＯを有している。
　ここで、ＬＰＳＯが針状若しくは板状をなすことによって、ＬＰＳＯが有するキンク帯の先鋭化が生じると共にＬＰＳＯが微細分散することとなり、結果としてマグネシウム合金の機械的特性（引張強度、０．２％耐力及び伸び）が向上することとなる。 [About needle-shaped or plate-shaped LPSO]
Further, as apparent from FIGS. 1B to 1D, the magnesium alloy of the present invention has a needle-like or plate-like LPSO.
Here, when the LPSO has a needle shape or a plate shape, the kink band of the LPSO is sharpened and the LPSO is finely dispersed. As a result, the mechanical properties of the magnesium alloy (tensile strength, 0.2%) Yield strength and elongation) will be improved.
　以下、本発明のマグネシウム合金の製造方法について説明を行う。
　図２は本発明を適用したマグネシウム合金の製造方法を説明するためのフローチャートである。図２に示す様に、本発明を適用したマグネシウム合金の製造方法では、先ず、鋳造工程Ｓ１により鋳造される。ここで、鋳造工程では、必須成分としてＺｎとＹを含有し、残部がＭｇと不可避的不純物とからなるＭｇ－Ｚｎ－Ｙ系合金を鋳造して、ＬＰＳＯとαＭｇ相とを含む鋳造材を形成する。なお、本実施例では、鋳造工程によって形成される鋳造材が、Ｍｇ９７Ｚｎ１Ｙ２合金である場合とＭｇ９６Ｚｎ２Ｙ２合金である場合を例に挙げて説明を行う。 Hereinafter, the manufacturing method of the magnesium alloy of this invention is demonstrated.
FIG. 2 is a flowchart for explaining a method for producing a magnesium alloy to which the present invention is applied. As shown in FIG. 2, in the manufacturing method of the magnesium alloy to which the present invention is applied, first, casting is performed by a casting step S1. Here, in the casting process, a casting material containing LPSO and α-Mg phase is formed by casting a Mg—Zn—Y alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities. To do. In this embodiment, the case where the cast material formed by the casting process is an Mg 97 Zn 1 Y 2 alloy and the case of an Mg 96 Zn 2 Y 2 alloy will be described as examples.
　次に、鋳造された鋳造材に、塑性加工工程Ｓ２を行う。この塑性加工工程の塑性加工は、例えば、押出加工、鍛造加工、圧延加工あるいは引抜加工等であり、鋳造材を塑性加工することによって得られる塑性加工物は、引張強度、伸び、０．２％耐力が著しく向上することとなる。 Next, a plastic working step S2 is performed on the cast material. The plastic processing in this plastic processing step is, for example, extrusion processing, forging processing, rolling processing or drawing processing, and the plastic processed product obtained by plastic processing of the cast material has tensile strength, elongation, 0.2%. The yield strength will be significantly improved.
　続いて、塑性加工された塑性加工物を３５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で熱処理（具体的には、焼きなまし処理）を施す熱処理工程Ｓ３を行う。 Subsequently, the plastic processed product is subjected to heat treatment (specifically, annealing treatment) within a temperature range of 350 ° C. to 500 ° C. and within a time range of 0.5 hours to 10 hours. A heat treatment step S3 is performed.
＜Ｍｇ９７Ｚｎ１Ｙ２合金の場合＞
　鋳造工程によって形成される鋳造材がＭｇ９７Ｚｎ１Ｙ２合金の場合には、熱処理工程によってαＭｇ相の結晶粒径が７μｍ～１５μｍとなる様に組織制御する。具体的には、３５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で熱処理を施すことによって、αＭｇ相の結晶粒径が７μｍ～１５μｍとなる様に組織制御する。一例としては、４００℃で１時間の熱処理を行うことで７μｍの結晶粒径を得ることができ、５００℃で１時間の熱処理を行うことで１０μｍの結晶粒径を得ることができ、５００℃で１０時間の熱処理を行うことで１５μｍの結晶粒径を得ることができる。 <In the case of Mg 97 Zn 1 Y 2 alloy>
When the cast material formed by the casting process is an Mg 97 Zn 1 Y 2 alloy, the structure is controlled by the heat treatment process so that the crystal grain size of the αMg phase becomes 7 μm to 15 μm. Specifically, by performing heat treatment within a temperature range of 350 ° C. or more and 500 ° C. or less and within a time range of 0.5 hours or more and 10 hours or less, the crystal grain size of the αMg phase becomes 7 μm to 15 μm. To control the organization. As an example, a crystal grain size of 7 μm can be obtained by performing heat treatment at 400 ° C. for 1 hour, and a crystal grain size of 10 μm can be obtained by performing heat treatment at 500 ° C. for 1 hour. A crystal grain size of 15 μm can be obtained by performing a heat treatment for 10 hours.
　なお、αＭｇ相の結晶粒径を７μｍ～１５μｍに組織制御しているのは、Ｍｇ９７Ｚｎ１Ｙ２合金の場合には、こうした範囲内に組織制御することによって、概ね３００ＭＰａ以上の引張強度と概ね１０％以上の伸びの双方を実現することができるからである（図５（ａ）参照。）。 The structure of the αMg phase crystal grain size is controlled to 7 μm to 15 μm in the case of Mg 97 Zn 1 Y 2 alloy by controlling the structure within such a range to obtain a tensile strength of approximately 300 MPa or more. This is because both elongations of approximately 10% or more can be realized (see FIG. 5A).
　ここで、図３（ａ）はＭｇ９７Ｚｎ１Ｙ２合金の押出材の結晶組織を示す顕微鏡写真であり、図３（ｂ）はＭｇ９７Ｚｎ１Ｙ２合金の３００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図３（ｃ）はＭｇ９７Ｚｎ１Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図３（ｄ）はＭｇ９７Ｚｎ１Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真である。図３（ａ）～図３（ｄ）の中で、本発明を適用したマグネシウム合金の製造方法によって得られたマグネシウム合金は、図３（ｃ）及び図３（ｄ）であるが、これらマグネシウム合金１は、その合金組織中に、ＬＰＳＯ２とαＭｇ相３とを有している。なお、図３（ａ）～図３（ｄ）で示す顕微鏡写真において、黒色で表されている箇所がＬＰＳＯであり、粒状に見える箇所がαＭｇ相である。 Here, Fig. 3 (a) is a micrograph showing the crystal structure of the extruded material of Mg 97 Zn 1 Y 2 alloy, and Fig. 3 (b) is an annealing of Mg 97 Zn 1 Y 2 alloy at 300 ° C for 1 hour. FIG. 3 (c) is a micrograph showing the crystal structure of the annealed material at 400 ° C. for 1 hour in the Mg 97 Zn 1 Y 2 alloy, and FIG. 97 Zn 1 Y 2 500 ℃ alloy is a photomicrograph showing the crystal structure of the annealed material an hour. 3 (a) to 3 (d), the magnesium alloys obtained by the magnesium alloy manufacturing method to which the present invention is applied are shown in FIGS. 3 (c) and 3 (d). Alloy 1 has LPSO 2 and αMg phase 3 in its alloy structure. In the micrographs shown in FIGS. 3 (a) to 3 (d), the black portions are LPSO, and the granular portions are αMg phases.
＜Ｍｇ９６Ｚｎ２Ｙ２合金の場合＞
　鋳造工程によって形成される鋳造材がＭｇ９６Ｚｎ２Ｙ２合金の場合には、熱処理工程によってαＭｇ相の結晶粒径が３μｍ～１０μｍとなる様に組織制御する。具体的には、３５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で熱処理を施すことによって、αＭｇ相の結晶粒径が３μｍ～１０μｍとなる様に組織制御する。一例としては、４００℃で１時間の熱処理を行うことで３μｍの結晶粒径を得ることができ、５００℃で１時間の熱処理を行うことで１０μｍの結晶粒径を得ることができる。 <In the case of Mg 96 Zn 2 Y 2 alloy>
When the cast material formed by the casting process is an Mg 96 Zn 2 Y 2 alloy, the structure is controlled by the heat treatment process so that the crystal grain size of the αMg phase becomes 3 μm to 10 μm. Specifically, by performing heat treatment within a temperature range of 350 ° C. or more and 500 ° C. or less and within a time range of 0.5 hours or more and 10 hours or less, the crystal grain size of the αMg phase becomes 3 μm to 10 μm. To control the organization. As an example, a crystal grain size of 3 μm can be obtained by performing heat treatment at 400 ° C. for 1 hour, and a crystal grain size of 10 μm can be obtained by performing heat treatment at 500 ° C. for 1 hour.
　なお、αＭｇ相の結晶粒径を３μｍ～１０μｍに組織制御しているのは、Ｍｇ９６Ｚｎ２Ｙ２合金の場合には、こうした範囲内に組織制御することによって、概ね３００ＭＰａ以上の引張強度と概ね１０％以上の伸びの双方を実現することができるからである（図５（ｂ）参照。）。 The structure of the αMg phase crystal grain size is controlled to 3 μm to 10 μm in the case of the Mg 96 Zn 2 Y 2 alloy, by controlling the structure within such a range, This is because both elongations of approximately 10% or more can be realized (see FIG. 5B).
　ここで、図３（ｅ）はＭｇ９６Ｚｎ２Ｙ２合金の押出材の結晶組織を示す顕微鏡写真であり、図３（ｆ）はＭｇ９６Ｚｎ２Ｙ２合金の３００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図３（ｇ）はＭｇ９６Ｚｎ２Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図３（ｈ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真である。図３（ｅ）～図３（ｈ）の中で、本発明を適用したマグネシウム合金の製造方法によって得られたマグネシウム合金は、図３（ｇ）及び図３（ｈ）であるが、これらマグネシウム合金１は、その合金組織中に、ＬＰＳＯ２とαＭｇ相３とを有している。なお、図３（ｅ）～図３（ｈ）で示す顕微鏡写真において、黒色で表されている箇所がＬＰＳＯであり、粒状に見える箇所がαＭｇ相である。 Here, FIG. 3 (e) is a photomicrograph showing the crystal structure of the extruded material of Mg 96 Zn 2 Y 2 alloy, and FIG. 3 (f) is an annealing of Mg 96 Zn 2 Y 2 alloy at 300 ° C. for 1 hour. FIG. 3 (g) is a micrograph showing the crystal structure of the annealed material at 400 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy, and FIG. 96 Zn 2 Y 2 500 ℃ alloy is a photomicrograph showing the crystal structure of the annealed material an hour. 3 (e) to 3 (h), the magnesium alloys obtained by the magnesium alloy manufacturing method to which the present invention is applied are shown in FIGS. 3 (g) and 3 (h). Alloy 1 has LPSO 2 and αMg phase 3 in its alloy structure. In the micrographs shown in FIGS. 3 (e) to 3 (h), the black portions are LPSO, and the granular portions are αMg phases.
　また、Ｍｇ９６Ｚｎ２Ｙ２合金を鋳造した場合には、鋳造時点で０．２μｍ～２．０μｍ程度の金属間化合物Ｍｇ３Ｚｎ３Ｙ２を形成していることが分かった。ここで、図４（ａ）はＭｇ９６Ｚｎ２Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図４（ｂ）はＭｇ９６Ｚｎ２Ｙ２合金の４５０℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図４（ｃ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、金属間化合物Ｍｇ３Ｚｎ３Ｙ２を形成していることが分かる。なお、図４（ａ）～図４（ｃ）で示す顕微鏡写真において、符号ｅで示す箇所が金属間化合物Ｍｇ３Ｚｎ３Ｙ２である。 Further, it was found that when the Mg 96 Zn 2 Y 2 alloy was cast, an intermetallic compound Mg 3 Zn 3 Y 2 having a thickness of about 0.2 μm to 2.0 μm was formed at the time of casting. Here, FIG. 4A is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour, and FIG. 4B is 450 of the Mg 96 Zn 2 Y 2 alloy. FIG. 4 (c) is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 1 hour in the Mg 96 Zn 2 Y 2 alloy. It can be seen that the intermetallic compound Mg 3 Zn 3 Y 2 is formed. In the micrographs shown in FIGS. 4 (a) to 4 (c), the part indicated by symbol e is the intermetallic compound Mg 3 Zn 3 Y 2 .
　ところで、図５（ａ）及び図５（ｂ）のグラフからも明らかな様に、鋳造工程によって形成される鋳造材がＭｇ９７Ｚｎ１Ｙ２合金の場合、Ｍｇ９６Ｚｎ２Ｙ２合金の場合の双方において、４００℃以上の温度で熱処理（具体的には、焼きなまし処理）を施した場合には、概ね３００ＭＰａ以上の引張強度を実現しつつ、概ね１２％以上の伸びを実現することができるマグネシウム合金を得ることができる。また、４５０℃以上の温度で熱処理（具体的には、焼きなまし処理）を施した場合には、概ね３００ＭＰａ以上の引張強度を実現しつつ、概ね１８％以上の伸びを実現することができるマグネシウム合金を得ることができる。 By the way, as apparent from the graphs of FIGS. 5A and 5B, when the cast material formed by the casting process is an Mg 97 Zn 1 Y 2 alloy, an Mg 96 Zn 2 Y 2 alloy is used. In both cases, when heat treatment (specifically, annealing treatment) is performed at a temperature of 400 ° C. or higher, an elongation of approximately 12% or more can be achieved while achieving a tensile strength of approximately 300 MPa or more. A magnesium alloy can be obtained. Further, when heat treatment (specifically, annealing treatment) is performed at a temperature of 450 ° C. or higher, a magnesium alloy that can achieve an elongation of approximately 18% or more while achieving a tensile strength of approximately 300 MPa or more. Can be obtained.
　ここで、図６（ａ）はＭｇ９６Ｚｎ２Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図６（ａ）で示す顕微鏡写真からＬＰＳＯがαＭｇ相粒内に析出していることが分かる。また、図６（ｂ）はＭｇ９６Ｚｎ２Ｙ２合金の４２５℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図６（ｂ）で示す顕微鏡写真からＬＰＳＯがαＭｇ相粒内に析出していることが図６（ａ）よりも明確に分かる。次に、図６（ｃ）はＭｇ９６Ｚｎ２Ｙ２合金の４５０℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図６（ｃ）で示す顕微鏡写真から針状若しくは板状のＬＰＳＯがαＭｇ相の粒界若しくは粒内若しくはその両方に析出し始めていることが分かる。続いて、図６（ｄ）はＭｇ９６Ｚｎ２Ｙ２合金の４７５℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図６（ｄ）で示す顕微鏡写真からαＭｇ相の粒界若しくは粒内若しくはその両方で針状若しくは板状のＬＰＳＯが成長し、また、針状若しくは板状のＬＰＳＯ同士が合体していることが分かる。更に、図６（ｅ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図６（ｅ）で示す顕微鏡写真からαＭｇ相の粒界若しくは粒内若しくはその両方で針状若しくは板状のＬＰＳＯが更に成長していることが分かる。なお、図６（ａ）～図６（ｅ）で示す顕微鏡写真において、黒色で表されている箇所がＬＰＳＯであり、粒状に見える箇所がαＭｇ相である。 Here, FIG. 6A is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour. From the micrograph shown in FIG. It turns out that it has precipitated in the grain. FIG. 6B is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 425 ° C. for 1 hour. From the micrograph shown in FIG. It can be clearly seen from FIG. Next, FIG. 6C is a photomicrograph showing the crystal structure of the annealed material at 450 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy. From the micrograph shown in FIG. It can be seen that the shaped LPSO is beginning to precipitate at the grain boundaries of αMg phase, within grains, or both. Next, FIG. 6 (d) is a micrograph showing the crystal structure of the annealed material at 475 ° C. for 1 hour of the Mg 96 Zn 2 Y 2 alloy. From the micrograph shown in FIG. 6 (d), grains of αMg phase It can be seen that needle-like or plate-like LPSO grows in the boundary and / or within the grains, and the needle-like or plate-like LPSOs are united with each other. Further, FIG. 6 (e) is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour. From the micrograph shown in FIG. 6 (e), αMg phase grain boundaries Alternatively, it can be seen that acicular or plate-like LPSO is further grown in the grains or both. In the micrographs shown in FIGS. 6A to 6E, the black portions are LPSO, and the granular portions are αMg phases.
　この様に、４００℃以上の温度で熱処理（具体的には、焼きなまし処理）を施すことにより、ＬＰＳＯ内に含まれていた２Ｈ構造を有するマグネシウム相が消失して安定組織であるＬＰＳＯが現出する結果となる。従って、上述の様に、概ね３００ＭＰａ以上の引張強度を実現しつつ、概ね１２％以上の伸びを実現することができるマグネシウム合金を得ることができるのである。 In this way, heat treatment (specifically, annealing treatment) at a temperature of 400 ° C. or higher causes the disappearance of the magnesium phase having a 2H structure contained in LPSO, and LPSO, which is a stable structure, appears. Result. Therefore, as described above, it is possible to obtain a magnesium alloy that can achieve an elongation of approximately 12% or more while achieving a tensile strength of approximately 300 MPa or more.
　更に、４５０℃以上の温度で熱処理（具体的には、焼きなまし処理）を施すことにより、現出したＬＰＳＯが針状組織若しくは板状組織を呈するために、押出加工材に比べてキンク帯の先鋭化が生じると共にＬＰＳＯが微細分散する結果となる。従って、上述の様に、概ね３００ＭＰａ以上の引張強度を実現しつつ、概ね１８％以上の伸びを実現することができるマグネシウム合金を得ることができるのである。 Furthermore, since heat treatment (specifically, annealing treatment) is performed at a temperature of 450 ° C. or higher, the appearing LPSO exhibits a needle-like structure or a plate-like structure, so that the kink band is sharper than the extruded material. As a result, LPSO is finely dispersed. Therefore, as described above, it is possible to obtain a magnesium alloy that can achieve an elongation of approximately 18% or more while achieving a tensile strength of approximately 300 MPa or more.
　なお、図７（ａ）はＭｇ９７Ｚｎ１Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図７（ｂ）はＭｇ９７Ｚｎ１Ｙ２合金の５００℃、５時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図７（ｃ）はＭｇ９７Ｚｎ１Ｙ２合金の５００℃、１０時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図７（ａ）で示す結晶組織も図７（ｃ）で示す結晶組織も、結晶粒径において大差はなく、本発明を適用したマグネシウム合金であるＭｇ９７Ｚｎ１Ｙ２合金が熱的安定性に優れていることが分かる。なお、マグネシウム合金の再結晶温度が３００℃程度であることに鑑みると、通常のマグネシウム合金の場合には、高温で長時間の熱処理を施した場合には、結晶粒径が成長することで伸びは改善するものの、引張強度が極端に低下してしまう。なお、図７（ａ）～図７（ｃ）で示す顕微鏡写真において、黒色で表されている箇所がＬＰＳＯであり、粒状に見える箇所がαＭｇ相である。 7A is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 1 hour in the Mg 97 Zn 1 Y 2 alloy, and FIG. 7B is 500 ° C. in the Mg 97 Zn 1 Y 2 alloy. FIG. 7C is a photomicrograph showing the crystal structure of the annealed material for 5 hours, and FIG. 7C is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 10 hours for the Mg 97 Zn 1 Y 2 alloy. The crystal structure shown in FIG. 7 (a) and the crystal structure shown in FIG. 7 (c) are not greatly different in crystal grain size, and the Mg 97 Zn 1 Y 2 alloy, which is a magnesium alloy to which the present invention is applied, has improved thermal stability. It turns out that it is excellent. In view of the fact that the recrystallization temperature of the magnesium alloy is about 300 ° C., in the case of a normal magnesium alloy, when the heat treatment is performed for a long time at a high temperature, the crystal grain size grows to increase the elongation. Is improved, but the tensile strength is extremely reduced. In the micrographs shown in FIGS. 7A to 7C, the black portions are LPSO and the granular portions are αMg phases.
　同様に、図７（ｄ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図７（ｅ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、５時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図７（ｆ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１０時間の焼きなまし材の結晶組織を示す顕微鏡写真であるが、図７（ｄ）で示す結晶組織も図７（ｆ）で示す結晶組織も、結晶粒径において大差はなく、本発明を適用したマグネシウム合金であるＭｇ９６Ｚｎ２Ｙ２合金は熱的安定性に優れていることが分かる。なお、図７（ｄ）～図７（ｆ）で示す顕微鏡写真において、黒色で表されている箇所がＬＰＳＯであり、粒状に見える箇所がαＭｇ相である。 Similarly, FIG. 7 (d) is a photomicrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 500 ° C. for 1 hour, and FIG. 7 (e) is a 500 photo of Mg 96 Zn 2 Y 2 alloy. FIG. 7 (f) is a photomicrograph showing the crystal structure of the annealed material at 500 ° C. for 10 hours of the Mg 96 Zn 2 Y 2 alloy, The crystal structure shown in FIG. 7 (d) and the crystal structure shown in FIG. 7 (f) are not greatly different in crystal grain size, and the Mg 96 Zn 2 Y 2 alloy, which is a magnesium alloy to which the present invention is applied, is thermally stable. It turns out that it is excellent in. In the micrographs shown in FIGS. 7D to 7F, the black portions are LPSO and the granular portions are αMg phases.
　また、図８（ａ）はＭｇ９６Ｚｎ２Ｙ２合金の４００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図８（ａ）で示す顕微鏡写真においては、ＬＰＳＯの結晶方位の向きやαＭｇ相の結晶方位の向きに規則性はなく、結晶方向の向きは乱れた状態であることが分かる。一方、図８（ｂ）はＭｇ９６Ｚｎ２Ｙ２合金の５００℃、１時間の焼きなまし材の結晶組織を示す顕微鏡写真であり、図８（ｂ）で示す顕微鏡写真においては、同一のＬＰＳＯ内の結晶方位の向きは全て同一であり、また、任意のＬＰＳＯ内の結晶方位の向きは、隣接するいずれかのαＭｇ相の結晶方位と同一であることが分かる。なお、任意のＬＰＳＯ内の結晶方位の向きが、隣接するαＭｇ相の双方と同一となることもあり得る。また、ＬＰＳＯの現出箇所はαＭｇ相の結晶粒界若しくは結晶粒内であって、結晶粒界と結晶粒内に現出する場合もある。 8A is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 alloy at 400 ° C. for 1 hour. In the micrograph shown in FIG. 8A, the crystal orientation of LPSO It can be seen that there is no regularity in the orientation of the crystal orientation of the α Mg phase and the orientation of the crystal orientation is disordered. On the other hand, FIG. 8 (b) is a micrograph showing the crystal structure of the annealed material of Mg 96 Zn 2 Y 2 at 500 ° C. for 1 hour. In the micrograph shown in FIG. 8 (b), the same LPSO It can be seen that the orientations of the crystal orientations are the same, and the orientation of the crystal orientation in any LPSO is the same as the crystal orientation of any of the adjacent αMg phases. Note that the orientation of crystal orientation in any LPSO may be the same as both of the adjacent αMg phases. In addition, the LPSO appears in the αMg phase grain boundaries or in the crystal grains, and may appear in the crystal grain boundaries and crystal grains.
　以下、本発明の実施例について説明する。なお、ここで示す実施例は一例であり本発明を限定するものではない。 Hereinafter, examples of the present invention will be described. In addition, the Example shown here is an example and does not limit this invention.
［実施例（１）］
　先ず、本発明の実施例（１）のマグネシウム合金の製造方法として、Ｚｎを１原子％、Ｙを２原子％とし、残部をＭｇと不可避的不純物のＭｇ－Ｚｎ－Ｙ合金をアルゴンガス雰囲気中の高周波溶解炉内で溶解を行った。次に、加熱溶解した材料を金型で鋳造し、φ２９ｍｍ×Ｌ６０ｍｍのインゴット（鋳造材）を作製した。続いて、押出温度３５０℃、押出比１０、押出速度２．５ｍｍ／ｓの条件で塑性加工（押出加工）を行い、その後１００℃～５００℃の熱処理温度にて１時間の熱処理（焼きなまし）を行ったものを作製した。 [Example (1)]
First, as a method for producing a magnesium alloy according to Example (1) of the present invention, Zn is 1 atomic%, Y is 2 atomic%, and the balance is Mg and an inevitable impurity Mg—Zn—Y alloy in an argon gas atmosphere. The melting was performed in the high frequency melting furnace. Next, the heat-dissolved material was cast with a mold to produce an ingot (cast material) of φ29 mm × L60 mm. Subsequently, plastic processing (extrusion processing) is performed under the conditions of an extrusion temperature of 350 ° C., an extrusion ratio of 10 and an extrusion speed of 2.5 mm / s, and then heat treatment (annealing) for 1 hour at a heat treatment temperature of 100 ° C. to 500 ° C. What was done was made.
　この様にして得られたそれぞれのマグネシウム合金を室温にて引張試験を行い、機械的特性を評価した結果を図５（ａ）に示す。 Each magnesium alloy thus obtained was subjected to a tensile test at room temperature, and the results of evaluating the mechanical properties are shown in FIG.
　図５（ａ）から明らかな様に、本発明の実施例（１）のマグネシウム合金の製造方法で得られるＭｇ９７Ｚｎ１Ｙ２合金は、３５０℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１０％以上の伸びを実現することができる。更に、図５（ａ）から明らかな様に、本発明の実施例（１）のマグネシウム合金の製造方法で得られるＭｇ９７Ｚｎ１Ｙ２合金は、４００℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１２％以上の伸びを実現し、４５０℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１８％以上の伸びを実現することができる。 As apparent from FIG. 5 (a), the Mg 97 Zn 1 Y 2 alloy obtained by the magnesium alloy production method of Example (1) of the present invention is approximately 300 MPa when annealed at a temperature of 350 ° C. or higher. While achieving the above tensile strength, it is possible to achieve an elongation of approximately 10% or more. Further, as is apparent from FIG. 5 (a), when the Mg 97 Zn 1 Y 2 alloy obtained by the magnesium alloy production method of Example (1) of the present invention is annealed at a temperature of 400 ° C. or higher, Achieving a tensile strength of approximately 300 MPa or more and an elongation of approximately 12% or more. When annealed at a temperature of 450 ° C. or more, a tensile strength of approximately 300 MPa or more is achieved and an elongation of approximately 18% or more is achieved. be able to.
［実施例（２）］
　また、本発明の実施例（２）のマグネシウム合金の製造方法として、Ｚｎを２原子％、Ｙを２原子％とし、残部をＭｇと不可避的不純物のＭｇ－Ｚｎ－Ｙ合金をアルゴンガス雰囲気中の高周波溶解炉内で溶解を行った。次に、加熱溶解した材料を金型で鋳造し、φ２９ｍｍ×Ｌ６０ｍｍのインゴット（鋳造材）を作製した。続いて、押出温度３５０℃、押出比１０、押出速度２．５ｍｍ／ｓの条件で塑性加工（押出加工）を行い、その後１００℃～５００℃の熱処理温度にて１時間の熱処理（焼きなまし）を行ったものを作製した。 [Example (2)]
In addition, as a manufacturing method of the magnesium alloy of Example (2) of the present invention, Zn is 2 atomic%, Y is 2 atomic%, and the balance is Mg and an inevitable impurity Mg—Zn—Y alloy in an argon gas atmosphere. The melting was performed in the high frequency melting furnace. Next, the heat-dissolved material was cast with a mold to produce an ingot (cast material) of φ29 mm × L60 mm. Subsequently, plastic processing (extrusion processing) is performed under the conditions of an extrusion temperature of 350 ° C., an extrusion ratio of 10 and an extrusion speed of 2.5 mm / s, and then heat treatment (annealing) for 1 hour at a heat treatment temperature of 100 ° C. to 500 ° C. What was done was made.
　この様にして得られたそれぞれのマグネシウム合金を室温にて引張試験を行い、機械的特性を評価した結果を図５（ｂ）に示す。 Each magnesium alloy thus obtained was subjected to a tensile test at room temperature, and the results of evaluating the mechanical properties are shown in FIG. 5 (b).
　図５（ｂ）から明らかな様に、本発明の実施例（２）のマグネシウム合金の製造方法で得られるＭｇ９６Ｚｎ２Ｙ２合金は、３５０℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１０％以上の伸びを実現することができる。更に、図５（ｂ）から明らかな様に、本発明の実施例（２）のマグネシウム合金の製造方法で得られるＭｇ９６Ｚｎ２Ｙ２合金は、４００℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１２％以上の伸びを実現し、４５０℃以上の温度で焼きなました場合には概ね３００ＭＰａ以上の引張強度を実現すると共に概ね１８％以上の伸びを実現することができる。 As apparent from FIG. 5 (b), the Mg 96 Zn 2 Y 2 alloy obtained by the magnesium alloy production method of Example (2) of the present invention is approximately 300 MPa when annealed at a temperature of 350 ° C. or higher. While achieving the above tensile strength, it is possible to achieve an elongation of approximately 10% or more. Further, as apparent from FIG. 5 (b), when the Mg 96 Zn 2 Y 2 alloy obtained by the magnesium alloy manufacturing method of Example (2) of the present invention was annealed at a temperature of 400 ° C. or higher, Achieving a tensile strength of approximately 300 MPa or more and an elongation of approximately 12% or more. When annealed at a temperature of 450 ° C. or more, a tensile strength of approximately 300 MPa or more is achieved and an elongation of approximately 18% or more is achieved. be able to.
　　　１　　マグネシウム合金
　　　２　　ＬＰＳＯ
　　　３　　αＭｇ相 1 Magnesium alloy 2 LPSO
3 αMg phase

Claims (11)

  1. 　必須成分としてＺｎとＹとを含有し、残部がＭｇと不可避的不純物からなるＭｇ－Ｚｎ－Ｙ系合金から構成されるマグネシウム合金であって、
    　Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、αＭｇ相と長周期積層構造相とを有し、
    　該長周期積層構造相の少なくとも一部が前記αＭｇ相とラメラ状に存在すると共に、該ラメラ状に存在する組織の少なくとも一部が湾曲または屈曲しており、
    　更に、湾曲または屈曲している部分でαＭｇ相と長周期積層構造相の不連続界面が形成され、若しくは、湾曲または屈曲している部分でαＭｇ相と長周期積層構造相の粒界が形成されている
    　マグネシウム合金。     A magnesium alloy composed of an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities;
    The alloy structure of the Mg—Zn—Y alloy has an αMg phase and a long-period laminated structure phase,
    At least a part of the long-period laminate structure phase is present in a lamellar form with the αMg phase, and at least a part of the tissue present in the lamellar form is curved or bent,
    Furthermore, a discontinuous interface between the αMg phase and the long-period laminate structure phase is formed at the curved or bent portion, or a grain boundary between the αMg phase and the long-period laminate structure phase is formed at the curved or bent portion. Magnesium alloy.
  2. 　必須成分としてＺｎとＹとを含有し、残部がＭｇと不可避的不純物からなるＭｇ－Ｚｎ－Ｙ系合金から構成されるマグネシウム合金であって、
    　Ｍｇ－Ｚｎ－Ｙ系合金の合金組織中に、針状若しくは板状の長周期積層構造相を有する
    　マグネシウム合金。     A magnesium alloy composed of an Mg—Zn—Y based alloy containing Zn and Y as essential components and the balance being Mg and inevitable impurities;
    A magnesium alloy having a needle-like or plate-like long-period laminated structure phase in an alloy structure of an Mg—Zn—Y alloy.
  3. 　前記長周期積層構造相が針状若しくは板状であり、同長周期積層構造相が有するキンク帯の先鋭化が生じると共に長周期積層構造相が微細分散した
    　請求項１に記載のマグネシウム合金。     The magnesium alloy according to claim 1, wherein the long-period multilayer structure phase is needle-shaped or plate-shaped, sharpening of the kink band of the long-period multilayer structure phase occurs, and the long-period multilayer structure phase is finely dispersed.
  4. 　前記αＭｇ相の結晶粒界若しくは結晶粒内またはその両方に長周期積層構造相を有しており、前記αＭｇの結晶粒内若しくは前記αＭｇ相の結晶粒界の少なくとも一方に、長周期積層構造相を有する
    　請求項１、請求項２若しくは請求項３に記載のマグネシウム合金。     The αMg phase has a long-period laminated structure phase in a crystal grain boundary or a crystal grain, or both, and a long-period laminated structure phase is present in at least one of the αMg crystal grain or the αMg phase crystal grain boundary. The magnesium alloy according to claim 1, claim 2, or claim 3.
  5. 　前記αＭｇ相の結晶粒内若しくは前記αＭｇ相の結晶粒界の少なくとも一方に、針状若しくは板状の長周期積層構造相を有する
    　請求項１、請求項２若しくは請求項３に記載のマグネシウム合金。     4. The magnesium alloy according to claim 1, wherein the magnesium alloy has a needle-like or plate-like long-period laminated structure phase in crystal grains of the αMg phase or at least one of crystal grain boundaries of the αMg phase.
  6. 　必須成分としてＺｎとＹを含有し、残部がＭｇと不可避的不純物とからなるＭｇ－Ｚｎ－Ｙ系合金を鋳造して、長周期積層構造相とαＭｇ相とを含む鋳造材を形成する鋳造工程と、
    　前記鋳造材に塑性加工を行う塑性加工工程と、
    　該塑性加工工程により塑性加工を施した前記鋳造材に熱処理を施す熱処理工程とを備えるマグネシウム合金の製造方法であって、
    　前記熱処理工程は、３５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で行う
    　マグネシウム合金の製造方法。     A casting process in which an Mg—Zn—Y alloy containing Zn and Y as essential components and the balance of Mg and inevitable impurities is cast to form a cast material including a long-period laminated structure phase and an αMg phase. When,
    A plastic working step for plastic working the cast material;
    A heat treatment step of heat-treating the cast material subjected to plastic working by the plastic working step;
    The said heat processing process is performed within the temperature range of 350 degreeC or more and 500 degrees C or less, and within the time range of 0.5 hours or more and 10 hours or less, The manufacturing method of the magnesium alloy.
  7. 　前記熱処理工程は、４００℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で行う
    　請求項６に記載のマグネシウム合金の製造方法。     The method for producing a magnesium alloy according to claim 6, wherein the heat treatment step is performed within a temperature range of 400 ° C. or more and 500 ° C. or less and within a time range of 0.5 hour or more and 10 hours or less.
  8. 　前記熱処理工程は、４５０℃以上５００℃以下の温度範囲内で、かつ、０．５時間以上１０時間以下の時間範囲内で行う
    　請求項６に記載のマグネシウム合金の製造方法。     The method for producing a magnesium alloy according to claim 6, wherein the heat treatment step is performed within a temperature range of 450 ° C. to 500 ° C. and within a time range of 0.5 hours to 10 hours.
  9. 　前記鋳造工程によりＭｇ９７Ｚｎ１Ｙ２合金よりなる鋳造材を形成すると共に、
    　前記熱処理工程によりαＭｇ相の結晶粒径を７μｍ以上１５μｍ以下に制御する
    　請求項６に記載のマグネシウム合金の製造方法。     In the casting process, a cast material made of Mg 97 Zn 1 Y 2 alloy is formed,
    The method for producing a magnesium alloy according to claim 6, wherein the crystal grain size of the αMg phase is controlled to 7 μm or more and 15 μm or less by the heat treatment step.
  10. 　前記鋳造工程によりＭｇ９６Ｚｎ２Ｙ２合金よりなる鋳造材を形成すると共に、
    　前記熱処理工程によりαＭｇ相の結晶粒径を３μｍ以上１０μｍ以下に制御する
    　請求項６に記載のマグネシウム合金の製造方法。     While forming a cast material made of Mg 96 Zn 2 Y 2 alloy by the casting process,
    The method for producing a magnesium alloy according to claim 6, wherein the crystal grain size of the αMg phase is controlled to 3 μm or more and 10 μm or less by the heat treatment step.
  11. 　前記熱処理工程により針状若しくは板状の長周期積層構造相を現出せしめる
    　請求項８に記載のマグネシウム合金の製造方法。     The method for producing a magnesium alloy according to claim 8, wherein a needle-like or plate-like long-period laminated structure phase is revealed by the heat treatment step.
PCT/JP2009/065701 2008-10-15 2009-09-09 Magnesium alloy and process for production thereof WO2010044320A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2008265830A JP2010095741A (en) 2008-10-15 2008-10-15 Method for manufacturing magnesium alloy
JP2008-265830 2008-10-15
JP2008270139A JP2010095787A (en) 2008-10-20 2008-10-20 Magnesium alloy and method for producing the same
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CN102822366A (en) * 2010-03-31 2012-12-12 国立大学法人熊本大学 Magnesium alloy sheet
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CN107312989B (en) * 2017-06-07 2018-09-04 河海大学 A kind of preparation method of nanocrystalline-Ultra-fine Grained gradient magnesium alloy containing LPSO structures

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