JP2009144215A - Heat resistant magnesium alloy material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat resistant magnesium alloy material having excellent high-temperature strength. <P>SOLUTION: The magnesium alloy material has a composition consisting of, by atom, 0.5 to 4% Zn, 0.5 to 4% Y, and the balance magnesium with inevitable impurities, and also has a structure in which α-phase Mg grain size is ≤50 μm and an Mg-Zn-Y compound is formed into network state in the grain boundaries thereof. The magnesium alloy material is obtained by carrying out solidification by a high-pressure casting process at 10 to 1,000°C/sec cooling rate. Owing to the Mg-Zn-Y compound formed into the network state in the grain boundaries, grain boundary sliding can be suppressed, high-temperature creep characteristics can be improved, and heat resistance can be increased. This magnesium alloy material is applicable to use under high-temperature environments, such as automotive parts concerned with engines, and can attain further weight reduction of the automotive parts. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-resistant magnesium alloy material suitable for use in high-temperature environments such as automobile parts around an engine, and excellent in high-temperature creep characteristics, and a method for producing the same.

  Magnesium alloys, which have the lightest specific gravity among structural metal materials, are used in portable electronic devices such as mobile phones and laptop computers, and housings for home appliances, etc., due to their characteristics. As an example of the alloy, AZ91D alloy excellent in strength, corrosion resistance, and castability is used. Further, magnesium alloys such as AM60B, AM50A, and AZ80A are also used for automobile parts such as a steering wheel and wheels for the purpose of energy saving, improvement of motion performance, and shock absorption.

With the aim of further increasing the strength of magnesium alloys, research on optimization of composition and processing methods has been actively conducted. As a result, it has been reported that, for example, a rapidly solidified material of Mg ₉₇ Zn ₁ Y ₂ alloy exhibits a yield strength of 600 MPa or more, and an extruded material of Mg—Zn—Y alloy ingot exhibits a yield strength of 400 MPa or more.

Patent Document 1 proposes a magnesium alloy containing 5-12 atomic% yttrium and 1-12 atomic% Zn in order to improve strength and elastic modulus.
In Patent Document 2, an Mg alloy including Zn 1 to 4 atomic% and Y 1 to 4.5 atomic%, and a composition ratio Zn / Y between Zn and Y in the range of 0.6 to 1.3. A method for producing a magnesium alloy is proposed in which an alloy structure containing an intermetallic compound Mg ₃ Y ₂ Zn ₃ and Mg ₁₂ Zn exhibiting a long-period structure is formed by plastic working after casting. Yes.

Furthermore, it is known that a magnesium alloy has a greater effect on increasing strength by refining crystal grains than an aluminum alloy or the like. For this reason, when rapid solidification or plastic working is used, the strength is increased by refining the crystal grains, so many studies have been carried out as methods for producing high-strength magnesium alloys (however, supersaturated solid solution + precipitation strengthening, There are also effects such as texture control).
For example, in Patent Document 3, a rapidly solidified material of Mg—Zn—X (where X is one or more elements selected from the group consisting of Y, Ce, La, Nd, Pr, Sm, and Mm) is used. Has been proposed.
JP 2005-213535 A JP 2006-97037 A Japanese Patent Laid-Open No. 7-3375

  By the way, if the parts around the engine that have the highest weight ratio after the body can be replaced with a lightweight magnesium alloy, the light weight effect will be great and the energy will be greatly saved. The development of the magnesium alloy as described above is strongly desired.

However, magnesium alloys such as AZ91D, AM60B, AM50A, and AZ80A contain Al as an alloy element, and form an Mg ₁₇ Al ₁₂ compound that causes a decrease in strength at a relatively low temperature. Therefore, they are inferior to aluminum alloys in high temperature characteristics. There is a drawback that it is difficult to use in parts that require high temperature characteristics such as around the engine. In order to improve heat resistance, magnesium alloys with improved high-temperature characteristics such as AE42 and AS41 alloys have been developed. However, since the performance is inferior to aluminum alloys, they have not been widely put into practical use.

  Further, the magnesium alloy disclosed in Patent Document 1 contains a large amount of yttrium and Zn, and when a large amount of alloy elements are added and cast in this manner, the amount of compound layer generated is increased and a coarse compound is generated. Even if the strength and the elastic modulus are increased, the ductility is lowered. Further, since it contains a large amount of expensive yttrium, it is difficult to apply it to members that are mass-produced. In addition, although the cooling rate is 50 ° C./s or less and casting is performed at a slower cooling rate than that of normal injection molding or die casting, the particle size of α-phase Mg is increased and the compound layer is coarse at such a cooling rate. Therefore, there is a problem that the high temperature creep resistance is low.

  The finer the metal structure, the easier the grain boundary slip occurs. In addition, since the grain boundary slip contributes greatly to the high temperature deformation of the magnesium alloy, it is necessary to control the structure to suppress the grain boundary slip in order to improve the high temperature characteristics of the magnesium alloy. That is, when crystal grains are refined by rapid solidification or plastic working, the high temperature characteristics contributed by the grain boundary sliding are not improved as much as normal temperatures, even though the normal temperature strength is increased.

In the manufacturing method shown in Patent Document 2, high-strength magnesium is produced by plastic working an alloy containing the intermetallic compound Mg ₃ Y ₂ Zn ₃ and Mg ₁₂ YZn having a long-period structure. Is excellent in high-temperature stability and excellent in consistency with α-phase Mg, so that high strength and high ductility can be achieved. However, when plastic processing such as extrusion is performed according to the manufacturing process specifically shown in Patent Document 2, the compound phase is divided by breaking the structure at the time of casting, and the coarseness before plastic processing By recrystallizing such α-phase Mg, a fine texture of α-phase Mg is formed, and as a result, a grain boundary in which the α-phase Mgs are adjacent to each other is formed. Therefore, a compound having excellent high-temperature stability does not exist at the grain boundary, and grain boundary sliding is likely to occur, resulting in poor high-temperature creep characteristics.

  Patent Document 3 proposes a rapidly solidified material. However, a rapid solidification method represented by a single roll method in which molten metal is jetted onto a roll and rapidly solidified is not effective for preventing magnesium combustion, oxidation, and explosion. Since it is necessary to carry out under an active gas atmosphere, the apparatus is large, and the productivity is inferior, resulting in high costs. Moreover, in the manufacturing method disclosed in Patent Document 3, in order to finally process the product, the obtained thin body is pulverized and packed in a can such as the same metal or aluminum, and plastic processing such as extrusion processing. This requires a plurality of steps of solidifying by means of, and further imparting a shape by forging or machining, so that it is not suitable for mass production in terms of cost and productivity. Further, the rapidly solidified material shown in Patent Document 3 is an Mg matrix, Mg—Zn, and Mg—X (where X is selected from the group consisting of Y, Ce, La, Nd, Pr, Sm, and Mm). Seed or two or more elements) based intermetallic compound dispersed phase, and fine intermetallic compounds are dispersed in the submicron Mg matrix. Mg—Zn-based compounds are disadvantageous in heat resistance because they have a lower melting point than Mg—Zn—Y-based compounds. Further, if the compound is dispersed in the matrix, it can be expected that the normal temperature strength is improved, but the effect of increasing the high temperature strength is hardly obtained.

  The present invention has been made against the background of the above circumstances, and an object thereof is to provide a heat-resistant magnesium alloy material excellent in high-temperature strength and a method for producing the same.

  That is, among the heat-resistant magnesium alloy materials of the present invention, the first present invention has a composition containing Zn of 0.5 to 4 atomic% and Y of 0.5 to 4 atomic%, with the balance being magnesium and inevitable impurities. The α-phase Mg crystal grain size is 50 μm or less, and a Mg—Zn—Y compound is generated in a network form at the grain boundary.

  The heat-resistant magnesium alloy material of the second aspect of the present invention is characterized in that, in the first aspect of the present invention, the Y / Zn ratio is 0.5 to 2 in the atomic% of Zn and Y.

  The heat-resistant magnesium alloy material of the third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, 0.5% or less of Zr is contained in the composition.

  According to a fourth aspect of the present invention, there is provided a method for producing a heat-resistant magnesium alloy material, wherein a magnesium alloy having the composition according to any one of the first to third aspects of the present invention is produced at 10 ° C./second to 1000 ° C./second by a high pressure casting method. The magnesium alloy material is obtained by solidifying at a cooling rate of 5%.

  According to a fifth aspect of the present invention, there is provided the method for producing a heat-resistant magnesium alloy material according to the fourth aspect of the present invention, wherein the high-pressure casting method is any one of an injection molding method, a die casting method, and a squeeze casting method. .

  The magnesium alloy material of the present invention has a final product shape, or is subsequently processed into a final product shape through secondary processing such as machining, and then subjected to plastic processing such as extrusion. Things are not included.

Next, the reasons for limiting the components and production conditions defined in the present invention will be described.
Zn: 0.5-4 atomic%
Y: 0.5-4 atomic%
In order to obtain high strength and ductility, Zn and Y are contained. However, if the content is small, the α-phase Mg is dissolved, and the compound phase is not generated, or the amount is decreased, and the compound phase is not generated in a network form. On the other hand, when there is too much content, there exists a possibility that ductility may fall because there are too many compound phases. Further, if a large amount of expensive Y is used, the cost increases and the corrosion resistance also deteriorates. Therefore, the contents of Zn and Y are defined above.

Y / Zn: 0.5-2
In order to produce an Mg—Zn—Y compound that can provide a pinning effect against grain boundary sliding at high temperatures, the Y / Zn ratio must be 0.5-2 as shown in FIG. . However, when the Y / Zn ratio is larger than 1, many Mg ₁₂ YZn phases are generated as the Mg—Zn—Y-based compound, and when the Y / Zn ratio is 1 or less, many Mg ₃ Y ₂ Zn ₃ phases are produced. Generated. Since Mg ₃ Y ₂ Zn ₃ in which a compound phase is formed in a granular form has a higher pinning effect on grain boundary sliding, a Y / Zn ratio of 1 or less is superior in high temperature creep characteristics.

Zr: 0.5 atomic% or less Zr has an effect of refining, has an effect of increasing strength, and is contained as desired. However, if it is too much, the formation of the compound phase may be inhibited, so the upper limit is made 0.5 atomic%.

α-phase Mg crystal grain size: 50 μm or less Excellent strength is achieved by setting the α-phase Mg crystal grain size to 50 μm or less.

Mg-Zn-Y compound Mg-Zn-Y compound surrounds α-phase Mg crystal grains and is formed at the grain boundary in a network shape, thereby suppressing the slip of the grain boundary and improving the high temperature creep characteristics. Increase strength. The Mg-Zn-Y compound is preferably at the grain boundary and covers the α-phase Mg crystal grains without gaps, but prevents slipping even if it is formed in a network by being present at most of the grain boundary. Demonstrate the effect. Examples of the Mg—Zn—Y compound include the Mg ₁₂ YZn phase and the Mg ₃ Y ₂ Zn ₃ phase as described above.

Solidification rate: 10 to 1000 ° C./second The α-phase Mg crystal grain size can be reduced by increasing the solidification rate, and the particle size can be 50 μm or less at a cooling rate of 10 ° C./second or more. On the other hand, when the molten metal is solidified at a cooling rate exceeding 1000 ° C./second, the Mg—Zn—Y compound is solid-dissolved and a compound phase is hardly generated. Even if the solid solution is heat-treated to precipitate the compound phase, it is finely precipitated and a structure in which the compound phase exists in a network form as in the present invention cannot be obtained.

High-pressure casting method By adopting the high-pressure casting method in the production method of the present invention, a magnesium alloy material having a final product shape or a shape close to this can be obtained, and thereafter, Mg-Zn generated at grain boundaries. The final product can be obtained without impairing the presence of the -Y compound. Examples of the high pressure casting method include injection molding, die casting, and squeeze casting.

  That is, according to the present invention, the composition contains Zn of 0.5 to 4 atomic% and Y of 0.5 to 4 atomic%, and the balance is composed of magnesium and inevitable impurities, and the α-phase Mg crystal grain size is 50 μm or less. And since the Mg-Zn-Y-type compound is produced | generated by the network form in the grain boundary, a grain boundary slip can be suppressed, a high temperature creep characteristic can be improved, and heat resistance can be improved. As a result, the present invention can be applied to use in high-temperature environments such as automobile parts around the engine, and further reduce the weight of the automobile parts.

  Hereinafter, an embodiment of the present invention will be described. In this embodiment, a thixomolding method by injection molding is adopted as a high pressure casting method.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 2 shows an injection molding machine 1 for a magnesium alloy, and a screw 3 is provided inside a cylinder 2. The screw 3 can be moved back and forth by rotation by a motor 4 and a hydraulic injection device, and the cylinder 2 and the screw 3 can melt and measure a metal material 5 as a molding material. An injection is performed. The metal material 5 is stored in the hopper 6 and supplied into the cylinder 2 by the feeder 7.

  A nozzle 10 is provided at the tip of the cylinder 2, and a molten molding material is injected by touching the nozzle 10 to the mold 15. A nozzle heater 11 and a cylinder heater 8 as heating means are provided on the outer circumferences of the nozzle 10 and the cylinder 2, respectively, and the nozzle 10 and the cylinder 2 are heated. The molding material heated by the nozzle heater 11 and the cylinder heater 8 is held as a molten or semi-molten molten metal in the reservoir 2 a and the nozzle 10 at the inner tip of the cylinder 2 and injected into the cavity of the mold 15. The

Next, the operation will be described using injection molding as a representative example. In thixomolding, light metal chips are used instead of pellets used in resin molding. The raw material chips are fed from the hopper 6 and are carried to the tip of the cylinder 2 by the rotation of the screw 3 while being heated by the heat from the cylinder 2 heated to the set temperature. Eventually, the shear force by the screw 3 and the heating from the cylinder 2 result in a semi-molten or completely melted state having thixotropic properties, and after being temporarily stored in front of the screw 3 at the tip of the cylinder 2, the mold 15 is moved at high speed. Molten metal is poured into the top. Although the molding conditions such as the cylinder 2 being heated to a high temperature close to 600 ° C. and the injection speed are significantly different from those of resin molding, the molding process is almost the same as that of resin injection molding. Therefore, it is excellent in productivity, and unlike plastic processing such as extrusion, a three-dimensional complex shape product can be formed in near net shape in almost one process. In the case of Mg ₉₆ Zn ₂ Y ₂ alloy, it has been confirmed that it can be molded at 610 to 630 ° C., which is near the liquidus temperature. The molten metal at 630 ° C. is filled at high speed into the mold at a screw speed of 2 m / s and an inflow rate of the molten metal of 100 to 200 m / s. Since the temperature of the mold is adjusted to 150 to 250 ° C., the molten metal deprived of heat by the mold is immediately solidified. In the molded product 20, the higher the cooling rate, the finer the crystal grains, and a compound phase is generated in the form of a network at the grain boundary at a cooling rate of 10 to 1000 ° C./second.

(Comparative Example 1)
In order to investigate the influence of the cooling rate, 170 g of Mg ₉₆ Zn ₂ Y ₂ alloy ingot was melted with a SUS304 crucible having an inner diameter of 34 mm and a height of 120 mm, and water cooling (cooling rate 7.5 ° C./s) from 695 ° C., air cooling (cooling) Speed 0.7 ° C./s). As shown in FIG. 3, the crystal grains became finer as the cooling rate increased. Moreover, when the cooling rate was low, adjacent crystal grains were not divided by the compound phase, showing dendrite and petal-like shapes, and the compound phase was also coarse. When the cooling rate is increased to some extent, the crystal grains are fine and the grain boundaries are covered with a thin compound phase. Therefore, a cooling rate of 10 ° C./second or more is necessary to obtain the effect of this patent. Such a cooling rate can be produced by a method of cooling and solidifying the molten metal by die casting such as injection molding or die casting.

Example 1
FIG. 4 shows the microstructure of an ingot of Mg ₉₆ Zn ₂ Y ₂ alloy and an injection molded body (molding temperature: 630 ° C., solidification rate: several hundred degrees C / sec) obtained by the injection molding machine of the embodiment.
An ingot has a crystal grain structure of about 100 μm, whereas an injection molded body has a fine structure with a grain size of several μm, and a compound mainly composed of a Mg ₃ Y ₂ Zn ₃ phase at the grain boundary. A phase exists.

(Example 2)
Next, FIG. 5 shows the creep curves of the conventional magnesium alloy injection molded and the Mg ₉₆ Zn ₂ Y ₂ alloy of Example 1 above. The creep test was conducted at a test temperature of 200 ° C. and a load of 90 MPa. As can be seen from the figure, it has been found that the conventional magnesium alloy has a smaller creep deformation resistance than the Mg ₉₆ Zn ₂ Y ₂ alloy of the present invention, and undergoes creep deformation in a short time. That is, even in an injection molded product, this alloy system is excellent in high-temperature creep characteristics because it is excellent in high-temperature stability.

(Example 3)
FIG. 6 shows the creep curves of Mg ₉₆ Zn ₂ Y ₂ alloy produced by various processing methods. The creep test was conducted at a test temperature of 225 ° C. and a load of 90 MPa.
In the figure,
THX: Injection molded body of Mg ₉₆ Zn ₂ Y ₂ alloy chip (molding temperature: 620 ° C., cooling rate: several hundred ° C./second)
EXT: Extruded material of Mg ₉₆ Zn ₂ Y ₂ alloy ingot (extrusion temperature 400 ° C., extrusion ratio 10)
CHEXT: Extruded material obtained by press-solidifying Mg ₉₆ Zn ₂ Y ₂ alloy chips (room temperature press-solidifying + extrusion temperature 400 ° C., extrusion ratio 10)
THX + CHEXT: Mg ₉₆ Zn ₂ Y ₂ alloy chip injection molded body (molding temperature 630 ° C), chipped and press-solidified, extruded material (extrusion temperature 400 ° C, extrusion ratio 10)
ADC12: ADC12 aluminum die-cast material THX material is an injection molded body of Mg ₉₆ Zn ₂ Y ₂ alloy.

  As can be seen from the figure, the creep deformation resistance of the injection molded product according to the present invention is greater than that of the extruded material of the ingot and the extruded material of the chip, which has been said to be able to increase the strength. .

FIG. 7 shows an extruded product of Mg ₉₆ Zn ₂ Y ₂ alloy (molding temperature: 630 ° C., cooling rate: several hundred degrees C / second), extruded material of Mg ₉₆ Zn ₂ Y ₂ alloy ingot (extrusion temperature 350 ° C., extrusion ratio 10). ) And an Mg ₉₆ Zn ₂ Y ₂ alloy injection-molded body (molding temperature 630 ° C.) are extruded (extrusion temperature 400 ° C., extrusion ratio 10).

  In the case of an extruded material, the structure is refined by processing and the compound phase is finely dispersed. On the other hand, in the injection molded product of the present invention, the compound phase exists on the network at the grain boundary. ing. Thereby, grain boundary sliding is suppressed and creep deformation is difficult at high temperatures. When an injection molded product that has a compound phase in the form of a network is extruded, the compound phase is dispersed in the same manner as the extruded material, and it is easy for creep deformation to occur. It is.

Example 4
Further, when comparing the mechanical properties of the injection molded body of Example 1 having a particle diameter of 100 μm or more and the coarse injection molding of Example 1 having a particle diameter of several μm, the ingot was 0.2 in the normal temperature tensile test. The 0.2% yield strength of the injection-molded product was as high as 209 MPa while the% yield strength was 125 MPa. This is because high-pressure casting sometimes reduces defects such as shrinkage cavities, but it is considered that the effect of increasing strength by crystal grain refinement that is generally known is great. That is, in order to produce a magnesium alloy with excellent mechanical properties, it is necessary to increase the strength by refining crystal grains and to form a compound phase having excellent high-temperature stability at the grain boundaries in a network form. Therefore, it is necessary to maintain the strength up to a high temperature.

(Example 5)
FIG. 8 shows creep curves of the injection-molded Mg ₉₇ Zn ₁ Y ₂ alloy and Mg ₉₆ Zn ₂ Y ₂ alloy (molding temperature: 630 ° C., solidification rate: several 100 ° C./second, respectively). When the Y / Zn ratio is greater than 1 (Mg ₉₇ Zn ₁ Y ₂ alloy), an Mg ₁₂ YZn phase is formed, and when the Y / Zn ratio is 1 or less (Mg ₉₆ Zn ₂ Y ₂ alloy), Mg ₃ Y ₂ Many Zn ₃ phases are generated. Mg ₃ Y ₂ Zn ₃ in which a compound phase is formed in a granular form has a higher pinning effect on grain boundary slipping. Therefore, in this patent, when the Y / Zn ratio is 1 or less, the high-temperature creep characteristics are superior. Conceivable.

(Example 6)
Using the Mg ₉₆ Zn ₂ Y ₂ alloy tip, the cylinder temperature is 630 ° C., the mold temperature is 160 ° C., the injection speed is 2 m / s, and the solidification speed is several hundred degrees C./sec. Tensile specimens were molded. Moreover, the tensile test piece of the same shape which consists of ADC12 aluminum alloy die-cast material and the heat-resistant heat-resistant magnesium alloy WE54-T6 as a comparative material was prepared.

A high temperature tensile test was conducted using these tensile test pieces. The result is shown in FIG.
As is clear from FIG. 9, it was found that the material of the present invention exhibits higher strength than the ADC12 aluminum alloy die-cast material. Moreover, it turned out that the intensity | strength substantially equivalent to heat-resistant heat-resistant magnesium alloy WE54-T6 is shown with the shaping | molding which does not heat-process.

(Example 7)
Next, the present invention material having a parallel part diameter of 6 mm under the conditions of a cylinder temperature of 620 ° C., a mold temperature of 160 ° C., an injection speed of 2 m / s, and a solidification speed of several hundred degrees C./second using an Mg ₉₆ Zn ₂ Y ₂ alloy chip. A creep test piece was formed. Moreover, the creep test piece of the same shape which consists of AM60B, AE42, and an ADC12 aluminum alloy die-cast material was prepared as a comparative material.

When a creep test was performed at a test temperature of 200 ° C. and a test load of 90 MPa, it was found that the material of the present invention exhibited excellent creep characteristics as compared with other magnesium alloy injection-molded bodies as shown in FIG. Further, when a creep test was performed at a test temperature of 200 ° C., 225 ° C., 250 ° C., and a test load of 90 MPa, it was found that the creep deformation resistance was higher at any temperature than the ADC12 aluminum die-cast material as shown in FIG. It was. Until now, magnesium alloys were inferior in high-temperature characteristics, especially high-temperature creep characteristics, so they were rarely used for automobile parts around engines where aluminum alloys are used. Since it can be shown, application to such a site is expected. The specific gravity of this magnesium alloy is 1.82, which is 2/3 that of aluminum alloy (2.7 in ADC12). Therefore, if parts that previously used aluminum alloy were made with this magnesium alloy, the weight was reduced. Effects such as energy saving and improvement of exercise performance can be obtained.
In addition, since the same structure is obtained even if the high pressure casting method (die casting) or the like that can obtain a cooling rate similar to that of the injection molding method is performed, the effect is equivalent to that of the present embodiment.

It is a phase diagram of a Mg-Zn-Y alloy. It is a cross-sectional side view which shows the injection molding apparatus of the magnesium alloy used for the manufacturing method of one Embodiment of this invention. Is a drawing-substituting photograph showing the microstructure of _Mg 96 _{Zn 2 Y} 2 alloy ingot manufactured at a cooling rate of 10 ° C. / sec or less in the embodiment. It is a drawing substitute photograph which similarly shows the microstructure of an ingot and an injection-molded body of Mg ₉₆ Zn ₂ Y ₂ alloy. Also the _Mg 96 _{Zn 2 Y} 2 alloy injection molded article, the conventional material and is AM60B and AE42 magnesium test temperature 200 ° C. of the alloy injection-molded article is a graph showing the high-temperature creep test results for load stress 90 MPa. Also various processing methods _Mg 96 _{Zn 2 Y} 2 test temperature 225 ° C. of the alloy produced in a graph showing the high-temperature creep test results for load stress 90 MPa. Also _Mg 96 _{Zn 2 Y} 2 alloy injection-molded _article, a photograph substituted for a drawing, showing the microstructure despite extruding the extruded material and _Mg 96 _{Zn 2 Y} 2 alloy injection-molded article of Mg 96 _{Zn 2 Y} 2 alloy ingot. Also is a graph showing the creep curve of the injection molded _Mg 97 _Zn 1 _{Y 2} alloy and _Mg 96 _{Zn 2 Y} 2 alloy. Also _Mg 96 _{Zn 2 Y} 2 alloy injection molded test temperature and relationship WE54-T6 material 0.2% proof stress (catalog value) is a graph comparing ADC12 aluminum alloy die material (the measured value). Also _Mg 96 _{Zn 2 Y} 2 alloy injection-molded article and ADC12 test temperature 200 ° C. of the aluminum alloy die casting material, 225 ℃, 250 ℃, it is a graph showing the high-temperature creep test results for load stress 90 MPa.

Explanation of symbols

1 Injection molding machine 2 Cylinder 3 Screw 15 Mold

Claims (5)

  Zn 0.5 to 4 atom% and Y 0.5 to 4 atom%, with the balance being composed of magnesium and inevitable impurities, α-phase Mg crystal grain size of 50 μm or less, A heat-resistant magnesium alloy material in which a Mg-Zn-Y-based compound is generated in a network form.   2. The heat-resistant magnesium alloy material according to claim 1, wherein a Y / Zn ratio is 0.5 to 2 in the atomic% of Zn and Y. 3.   3. The heat-resistant magnesium alloy material according to claim 1, wherein the composition contains 0.5 atomic% or less of Zr.   A magnesium alloy material obtained by solidifying a magnesium alloy having the composition according to any one of claims 1 to 3 at a cooling rate of 10 ° C / second to 1000 ° C / second by a high pressure casting method. Manufacturing method of magnesium alloy material.   The method for producing a heat-resistant magnesium alloy material according to claim 4, wherein the high-pressure casting method is any one of an injection molding method, a die casting method, and a squeeze casting method.