JP2014124668A - Production method of magnesium alloy cast material, magnesium alloy cast material, expanded material of magnesium alloy, and molding of magnesium alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a magnesium alloy cast material excellent in moldability.SOLUTION: A production method of a magnesium alloy cast material includes a dissolution step for dissolving a magnesium alloy containing aluminum as an additive element to obtain a molten metal 1, and a casting step for producing a casting material 2 by solidifying the molten metal 1, and further includes a contact step for bringing the molten metal 1 into contact with a carbon material by the time of the casting step. In the contact step, assuming that the contact area (mm) of the molten metal 1 to the carbon material is S and the contact time (sec) between the carbon material and the molten metal is T, the product S×T of the contact area and the contact time is 5.0×10(mm×sec) or more.

Description

  The present invention relates to a method for producing a cast material of magnesium alloy, a cast material of magnesium alloy produced by the production method, a wrought material of magnesium alloy obtained by plastic processing of the cast material of magnesium alloy, and the magnesium alloy The present invention relates to a magnesium alloy molded product obtained by press-molding the wrought material. In particular, the present invention relates to a production method capable of producing a cast material of a magnesium alloy having excellent formability.

  Magnesium (hereinafter referred to as Mg) alloy has excellent characteristics such as light weight and high specific strength, so that it can be used for portable electrical and electronic equipment such as mobile phones and notebook personal computers, as well as aircraft and automobile parts. It is used for various members. The cast material of Mg alloy used as the material of these Mg alloy members is manufactured by, for example, a continuous casting method such as a twin roll method or a twin belt method. As an apparatus used for the continuous casting method, for example, there is one shown in Patent Document 1.

  The continuous casting apparatus of Patent Document 1 includes a melting furnace (crucible) that melts Mg alloy to form a molten metal, a hot water reservoir (holding furnace) that temporarily stores molten metal from the melting furnace, and a molten metal from the melting furnace. A transfer trough for transporting the molten metal and a supply unit for supplying the molten metal from the hot water to the casting roll are provided. The melting furnace and the hot water reservoir are formed of a carbon-based material such as carbon (graphite). The cast material of Mg alloy obtained from such a casting apparatus is processed into an Mg alloy member by performing plastic working.

JP 2011-45928 A

  It is required to further improve the productivity of the Mg alloy member. As a measure for improving the productivity of the Mg alloy member, an improvement in the formability of the cast material can be mentioned. In order to improve the moldability of the cast material, it is considered that a fine and uniform cast structure is sufficient. However, a specific casting technique for easily obtaining a fine and uniform cast structure has not been proposed.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a method for producing a cast material of Mg alloy that can produce a cast material of Mg alloy having excellent formability.

  Another object of the present invention is a cast material of Mg alloy produced by the above production method, a wrought material of Mg alloy obtained by plastic processing of the cast material, and press-molded on the wrought material of Mg alloy. The object is to provide a molded product of Mg alloy.

In order to achieve the above-mentioned object, the present inventors diligently studied a method for producing a cast material of Mg alloy. As a result, in the case of an Mg alloy containing aluminum (hereinafter referred to as Al), Al contained in the molten metal reacts with carbon (hereinafter referred to as C) of the carbon material to form a solidified nucleus composed of Al ₄ C _3. The inventors have found that the crystal grain size of the cast material can be reduced and the variation in crystal grain size can be reduced, thereby obtaining a cast material having excellent moldability. In addition, it was also found that the contact time and the contact area between the molten Mg alloy and C are important parameters for the formation of solidification nuclei that contribute to the refinement and homogenization of the crystal grain size. Based on these findings, the present invention is defined below.

The method for producing a cast member of Mg alloy according to the present invention includes a melting step of melting an Mg alloy containing Al as an additive element to make a molten metal, and a casting step of producing a cast material by solidifying the molten metal. Furthermore, a contact step of bringing the molten metal into contact with the carbon material by the casting step is provided. In the contact step, when the contact area (mm ² ) of the molten metal with respect to the carbon material is S and the contact time (sec) between the carbon material and the molten metal is T, the product S × T of the contact area and the contact time is 5 0.0 × 10 ⁹ (mm ² × sec) or more.

  In the method for producing a cast member of Mg alloy according to the present invention, the molten metal is sufficiently brought into contact with the carbon material so that the product of the contact area and the contact time satisfies the above range, so that Al in the molten metal and C of the carbon material are sufficient Thus, a solidified nucleus composed of Al and C can be effectively formed, so that a cast material having a fine and uniform crystal grain structure (small variation in grain size) can be produced. Since this cast material has a coarse crystal grain size, a fine crystal grain structure with a small variation in grain size, cracks are less likely to occur by subsequent plastic working. That is, according to the manufacturing method of the present invention, a cast material having excellent formability can be manufactured.

  As one form of the manufacturing method of this invention, it is mentioned that the temperature of the carbon material made to contact with a molten metal is 600 degreeC or more.

  According to said structure, reaction with Al in molten metal and C of carbon material can be accelerated | stimulated. Therefore, a solidified nucleus can be formed effectively, and a cast material having a fine grain structure with small variation in grain size can be produced.

  As one form of the manufacturing method of this invention, it is mentioned that the contact time of a molten metal and a carbon material is 10,000 sec or more.

  According to said structure, by making the said contact time into 10000 sec or more, Al and C in a molten metal can react, and it can form a solidification nucleus, and the crystal grain structure | tissue which has a small and small dispersion | variation in a particle size is formed. The cast material which has can be manufactured.

  One aspect of the production method of the present invention includes a holding step. In this case, the melting step is performed in a melting furnace made of a material other than the carbon material, and the molten metal from the melting furnace is temporarily stored in the holding furnace made of the carbon material in the holding step. And a contact process is given at a holding process.

  According to the above configuration, the melting furnace is made of a material other than a carbon material, and the holding furnace is made of a carbon material, so that the moldability is excellent and the details will be described in the embodiments described later. A cast material of Mg alloy having excellent internal properties can be manufactured.

  As one form of the manufacturing method of this invention, it is mentioned that content of Al in Mg alloy is 1 mass% or more and 12 mass% or less.

  According to said structure, the casting material of Mg alloy which is excellent in corrosion resistance and a mechanical characteristic can be manufactured because Al contains in said range.

  As an embodiment of the Mg alloy member of the present invention, the Mg alloy contains Al in a range of 8.3 mass% to 9.5 mass% and zinc (Zn) in a range of 0.5 mass% to 1.5 mass%. Is mentioned.

  According to said structure, while being excellent in corrosion resistance, the casting material of Mg alloy which is excellent also in a mechanical characteristic can be manufactured.

  The cast material of Mg alloy of the present invention is obtained by the above-described method for producing a cast material of Mg alloy of the present invention.

  Since the cast material of the Mg alloy of the present invention has a fine grain structure with a small grain size variation, cracking and the like are hardly caused by plastic working, and the moldability is excellent. This is because when the molten metal is brought into contact with the carbon material during production, Al contained in the molten metal and C of the carbon material react to form solidified nuclei. The wrought material of the Mg alloy of the present invention obtained by plastic processing of this cast material, and the molded product of the Mg alloy of the present invention obtained by press molding this wrought material have few defects such as cracks. High quality.

  The method for producing a cast material of Mg alloy of the present invention can produce a cast material of Mg alloy having excellent formability.

  The cast material of the Mg alloy of the present invention is excellent in formability.

  The wrought material and molded product of the Mg alloy of the present invention are of high quality.

It is a schematic block diagram of the twin roll type continuous casting apparatus used in the embodiment. It is a graph which shows the relationship between the contact area x contact time in a test example, and an average crystal grain size. Sample No. It is an optical microscope photograph which shows the cross section of 1 cast material.

  Embodiments of the present invention will be described below.

<< Manufacturing Method of Magnesium Alloy Cast Material >>
The manufacturing method of the cast material of Mg alloy of this invention comprises the melting process which melt | dissolves Mg alloy to make a molten metal, and the casting process which solidifies a molten metal and manufactures a cast material. The main feature of this manufacturing method is that it comprises a contact step in which the molten metal and the carbon material are brought into contact by the casting step, and in the contact step, the product of the contact area and the contact time is a specific value or more. There is in point to do. First, the composition of the Mg alloy, which is a constituent material of the cast material to be manufactured, will be described, and then the manufacturing method of the present invention will be described based on an example of an apparatus used for casting shown in FIG.

[Magnesium alloy]
In producing a cast material of Mg alloy, the Mg alloy to be prepared is an Mg-Al alloy that contains at least Al as an additive element and the balance is composed of Mg and inevitable impurities.

  The content of Al is preferably 1% by mass or more, more preferably 3% by mass or more, particularly 5.5% by mass or more, and even more preferably 7.3% by mass or more. The higher the Al content, the better the hot water flow during production and the better the castability. Further, the manufactured member (cast material) tends to have excellent corrosion resistance and mechanical properties such as strength and plastic deformation resistance. However, if the Al content exceeds 12% by mass, the plastic workability is lowered, so the upper limit is 12% by mass. The Al content is preferably 11% by mass or less, more preferably 10.5% by mass or less, and particularly preferably 8.3% by mass to 9.5% by mass.

  Mg alloys include those having various compositions containing various additive elements in addition to Al. Specific additive elements are selected from Zn, Mn, Si, Be, Ca, Sr, Y, Cu, Ag, Sn, Li, Zr, Ce, Ni, Au, and rare earth elements (excluding Y and Ce). 1 type or more elements. When such elements are included, the total content is 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 5% by mass or less. Among these additive elements, at least one element selected from Si, Sn, Y, Ce, Ca, and rare earth elements (excluding Y and Ce) is in total 0.001% by mass or more, preferably in total 0.1 When it is contained in an amount of from 5% by mass to 5% by mass, it is excellent in heat resistance and flame retardancy. When the rare earth element is contained, the total content is preferably 0.1% by mass or more, and particularly when Y is contained, the content is preferably 0.5% by mass or more. Examples of the impurities include Fe.

  More specific compositions of Mg-Al alloys include, for example, AZ-based alloys (Mg-Al-Zn-based alloys, Zn: 0.2 mass% to 1.5 mass%) in ASTM standards, AM-based alloys (Mg -Al-Mn alloy, Mn: 0.05 mass% to 0.5 mass%), AS alloy (Mg-Al-Si alloy, Si: 0.3 mass% to 4.0 mass%), Mg -Al-RE (rare earth element) based alloy, AX based alloy (Mg-Al-Ca based alloy, Ca: 0.2 mass% to 6.0 mass%), AZX based alloy (Mg-Al-Zn-Ca based) Alloy, Zn: 0.2 mass% to 1.5 mass%, Ca: 0.1 mass% to 4.0 mass%), AJ alloy (Mg—Al—Sr alloy, Sr: 0.2 mass%) -7.0 mass%) and the like. In particular, Mg—Al based alloys, typically AZ91 alloy, containing Al from 8.3 mass% to 9.5 mass% and Zn from 0.5 mass% to 1.5 mass% have corrosion resistance and mechanical properties. It is excellent and preferable.

[Casting equipment]
Next, a twin-roll type continuous casting apparatus 100 for Mg alloy that supplies molten Mg alloy to the movable mold using its own weight will be described with reference to FIG. The apparatus 100 includes a melting furnace (crucible) 10 that melts an Mg alloy to form a molten metal 1, a holding furnace 12 that temporarily stores the molten metal 1 from the melting furnace 10, and a molten metal 1 that is supplied from the holding furnace 12. And a pair of rolls 14 for forming the cast material 2. The melting furnace 10 and the holding furnace 12 are connected by a transfer rod 11 that transports the molten metal 1 from the melting furnace 10 to the holding furnace 12. A supply unit 12 d including a pouring port 13 for supplying the molten metal 1 from the holding furnace 12 to the roll 14 is connected to the roll 14 side of the holding furnace 12, and the pouring port 13 side of the supply unit 12 d is close to or in contact with the roll 14. Are arranged as follows. A heater (not shown) can be provided in each of the melting furnace 10, the transfer rod 11, the holding furnace 12, the supply unit 12d, and the pouring port 13 so that the temperature of the molten metal 1 can be adjusted.

  A cast material is manufactured using such a continuous casting apparatus 100.

In the manufacturing method of the present invention, the molten metal 1 is brought into contact with the carbon material until the molten metal 1 is solidified to form the cast material 2. At that time, when the contact area (mm ² ) of the molten metal 1 with respect to the carbon material is S and the contact time (sec) between the carbon material and the molten metal is T, the product S × T of the contact area S and the contact time T is 5 The molten metal 1 and the carbon material are brought into contact with each other so as to be 0.0 × 10 ⁹ (mm ² × sec) or more. Then, Al in the molten metal and C of the carbon material can react to form solidified nuclei, and a cast material having a fine and uniform crystal grain structure can be manufactured (small variation in grain size). The fine crystal grain structure means that the average crystal grain size is 35 μm or less. The average crystal grain size is preferably 35 μm or less, particularly preferably 30 μm or less.

  Specifically, the part which contacts the molten metal 1 of the continuous casting apparatus 100 is made of a carbon material. For example, in the continuous casting apparatus 100, at least (1) both the melting furnace 10 and the holding furnace 12 are made of a carbon material, (2) the melting furnace 10 is made of a carbon material, and the holding furnace 12 is made of a material other than the carbon material, (3) The melting furnace 10 may be made of a material other than a carbon material, and the holding furnace 12 may be made of a carbon material. Among these, it is preferable that the melting furnace 10 is made of a material other than the carbon material and the holding furnace 12 is made of the carbon material as in (3) above. If it does so, while being excellent in a moldability, the casting material of Mg alloy which is excellent also in surface property and internal property can be manufactured. Usually, the melting furnace 10 is filled with an Mg alloy at any time, so that Be (beryllium) is often added so that the molten metal is not oxidized at that time. However, Be is easy to react with C, and if the melting furnace 10 is made of a carbon material, Be reacts with C and the amount of metal Be in the molten metal is reduced, so that it is difficult to obtain an antioxidant effect. On the other hand, when the holding furnace 12 is made of a carbon material, even if Be in the molten metal reacts with C in the holding furnace 12, the holding furnace 12 is often sealed in general, and the melting furnace 10 has a higher atmosphere than the molten metal. This is because there is little problem even if the antioxidant effect is reduced because they do not touch each other.

For example, when the constituent materials of the melting furnace 10 and the holding furnace 12 are the above (1), since the melting furnace 10 and the holding furnace 12 are made of a carbon material, the molten metal 1 is composed of the melting furnace 10 and the holding furnace 12. Both are in contact with carbon materials. That is, the contact area S ₁ is a region where the molten furnace 10 and the molten metal in the holding furnace 12 are in contact with each other, and the time is the contact time T ₁ , and the product S ₁ × T ₁ is 5.0 × 10 ⁹ (mm ² × sec). ) The molten metal and the carbon material are brought into contact with each other so as to achieve the above. Similarly, in the case of (2) above, since the melting furnace 10 is made of a carbon material, the area in contact with the molten metal in the melting furnace 10 is defined as the contact area S ₂ , the time as the contact time T ₂ , The product S ₂ × T _{2 is set} to 5.0 × 10 ⁹ (mm ² × sec) or more. In the case of the above (3), since the holding furnace 12 is made of a carbon material, the area in contact with the molten metal in the holding furnace 12 is a contact area S ₃ , the time is the contact time T ₃ , and the product S ₃ × and _{T 3} a ^{5.0 × 10 9 (mm 2 ×} sec) or more.

  In addition, when all of the melting furnace 10, the transfer rod 11, the holding furnace 12, the supply unit 12 d, and the pouring port 13 are made of a carbon material, until the Mg alloy is melted in the melting furnace 10 and contacts the roll 14, The molten metal comes into contact with a member made of a carbon material. At this time, the contact area between the molten metal and the carbon material is the entire surface area in contact from the melting furnace 10 to the pouring port 13. In this case, the contact area may be the same as in the case of (1) above. This is because the contact time of the molten metal at the transfer trough 11 and the supply unit 12d is short, so that the contact time can be ignored. That is, the contact area between the molten metal and the carbon material in the melting furnace 10 and the holding furnace 12 is S, and the contact time is T.

  The contact time T is preferably 10,000 seconds or longer. The longer the contact time T, the more effectively the solidified nuclei can be formed by the reaction between Al in the molten metal and C of the carbon material, and it is possible to produce a cast material having a fine and small grain size variation. . Although the upper limit of this contact time T is not specifically limited, It is preferable to set it as about 100,000 seconds on the efficiency of manufacturing operation.

  When the molten metal is brought into contact with the carbon material, the temperature of the carbon material is preferably 600 ° C. or higher. For example, when the holding furnace 12 is made of a carbon material, it is preferable to store the molten metal 1 by heating the temperature of the holding furnace 12 to 600 ° C. or higher. By doing so, Al in the molten metal and C constituting the holding furnace 12 can easily react with each other, can effectively form solidification nuclei, and has a fine grain structure with a small grain size variation. Can be manufactured. The upper limit of this temperature is about 800 ° C.

  As this carbon material, for example, a material having a high carbon content is preferable. A material having a high carbon content refers to a material having a carbon content of 10% by mass or more. The carbon content is preferably 30% by mass or more, particularly 70% by mass or more, and more preferably 90% by mass or more. Specific examples include carbon (graphite). On the other hand, examples of the material other than the carbon material include materials that do not react with Al in the molten metal and do not affect the formation of solidified nuclei. Specific examples include molybdenum, boron nitride, copper, copper alloys such as brass, iron, and stainless steel.

<Effect>
The above-described method for producing a cast material of Mg alloy can produce a cast material having excellent formability. By contacting the molten metal and the carbon material so that the product of their contact area and contact time satisfies a specific range, the molten nuclei and the carbon material C are sufficiently reacted to effectively solidify the nucleus. This is because, since the solidification nuclei can be uniformly dispersed, a cast material having a fine and uniform crystal grain structure can be produced. Therefore, this cast material is not easily cracked by subsequent plastic working.

<< Test Example 1 >>
Using the continuous casting apparatus 100 described above, a plurality of cast materials of Mg alloy were manufactured, and the cast materials were analyzed and evaluated. In this example, the holding furnace 12 has a substantially cylindrical shape (inner diameter φ: about 400 mm) made of carbon.

An AZ91-equivalent Mg alloy (Al: 8.3% to 9.5%, Zn: 0.2% to 1.5% contained (all by mass%)) was prepared and melted to obtain a molten metal 1. Thereafter, the molten metal 1 was supplied to the roll 14 through the pouring port 13 to produce a sample of a cast material (cast plate) 2 having a thickness of 4 mm and a width of 200 mm. In this example, the contact time between the molten metal 1 and the carbon material (the storage time of the molten metal in the holding furnace 12) was variously changed as shown in Table 1, and 75 kg of the cast materials of Samples 1 to 6 were produced. The contact time of each sample was changed by adjusting the time for holding the molten metal in the holding furnace 12. In Samples 1 and 2, the Mg alloy was melted in the holding furnace 12, and the melting furnace 10 was not used. In the sample 3, the molten metal 1 was melted in the melting furnace 10 and temporarily stored, and the molten metal 1 was transferred to the holding furnace 12 in which the molten metal 1 was stored for a predetermined time in advance. That is, the contact time and the contact area are values calculated by averaging both the melting furnace and the holding furnace. In the samples 4 to 6, the molten metal 1 is temporarily stored by melting in the melting furnace 10, the molten metal 1 is transferred to the holding furnace 12, and the molten furnace 1 is not stored in the holding furnace 12 through the pouring port 13 as it is. And supplied to the roll 14. That is, the contact time and the contact area are values only during the temporary contact with the holding furnace 12. The area where the molten metal 1 in each sample was in contact with the carbon material was as shown in Table 1, and the contact area of each sample with the carbon material per kg of the molten metal was about 7600 mm ² . Table 1 shows the contact area S, the contact time T, and the product S × T between the molten metal 1 and the carbon material.

[Section observation]
The average crystal grain size of the obtained cast material was measured. Here, it calculated | required by the cutting method prescribed | regulated to the "microscope test method JIS G 0551 (2005)" of the steel-crystal grain size. Specifically, the test piece was cut, and the cut surface was buffed (diamond abrasive grains # 200), then subjected to etching treatment, and the structure was observed in a 100-fold field of view of an optical microscope. The average crystal grain size was determined. The measurement results are shown in Table 1 and FIG. Sample No. For No. 1, crystal grains were observed in a 400 × field of view of an optical microscope. The result is shown in FIG.

[Number of cracks by bending test]
The obtained cast material of each sample was rolled to produce a stretched material (rolled plate) having a thickness of 0.8 mm and a width of 200 mm, and a bending test was performed on the stretched material. The rolling process was performed by heating the cast material at 400 ° C. for 24 hours and cooling it, and then heating the cast material to 250 ° C. in a warm manner. In addition, rolling was performed in a plurality of passes at a reduction rate of 20% per pass. In the bending test, the wrought material is cut into an appropriate length to produce a plurality of test pieces, each of the test pieces is press-formed in a state heated to 250 ° C., and each test piece is moved along the rolling direction. Bent at a right angle. Here, the number and length of the test pieces were adjusted so that the total length in the rolling direction of the plurality of test pieces was 1 m or more. In the bending test, the bending radius R inside the bent portion of the test piece was set to 0.5 mm. And the outer surface of the bending part of each test piece was observed visually over the rolling direction full length, and the number of cracks which generate | occur | produced in the bending part was measured. In this example, for each sample, a bending test was performed on eight test pieces, and the number of cracks (pieces) of each test piece was measured to obtain an average value. Evaluation was performed by converting this into the number of cracks (pieces / m) when the length of the test piece (rolled material) in the rolling direction was 1 m. The results are shown in Table 1.

[result]
As shown in Table 1 and FIG. 2, the longer the contact time, the smaller the crystal grain size, and Samples 1 and 2 had a smaller average crystal grain size than Samples 3-6. Samples 1 and 2 had fewer cracks than Samples 3-6. As a result of observing the cross section of the sample 1, formation of solidified nuclei 3 made of Al ₄ C ₃ was observed as shown by a broken-line circle in FIG. It can be seen that the black dot is the solidification nucleus 3 in the broken-line circle in the figure, and the gray dendrite spreads radially around it. Although not shown in Table 1 or FIG. 2, it is considered that the variation in crystal grain size becomes smaller as the contact time becomes longer. Samples 1 and 2 have a variation in crystal grain size compared to Samples 3-6. It is considered small.

In sample 1, the contact time between the molten metal and the carbon material was long, and Al in the molten metal and C of the carbon material reacted sufficiently, so that the solidification nucleus 3 made of Al ₄ C ₃ shown in FIG. 3 could be effectively formed. It is thought. Accordingly, a cast material having a fine grain structure with a small grain size variation can be produced, and the number of cracks is considered to be extremely small compared to Samples 3-6. Sample 2 can be said to be the same as Sample 1.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, a rod-shaped member made of a carbon material can be directly immersed in the molten metal so that the molten metal and the carbon material are brought into contact with each other. Further, the contact area between the molten metal and the carbon material can be increased by making the inner peripheral surface of the melting furnace or holding furnace uneven.

  The method for producing a cast material of Mg alloy of the present invention can be used for producing a cast material of Mg alloy. The cast material, wrought material, and molded product of the Mg alloy of the present invention can be used as a member of the Mg alloy.

DESCRIPTION OF SYMBOLS 100 Twin roll type continuous casting apparatus 1 Molten metal 2 Cast material 3 Solidification nucleus 10 Melting furnace 11 Transfer rod 12 Holding furnace 12d Supply part 13 Pouring spout 14 Roll

Claims (9)

A method for producing a magnesium alloy casting material comprising: a melting step of melting a magnesium alloy containing aluminum as an additive element to form a molten metal; and a casting step of solidifying the molten metal to produce a cast material,
Comprising a contact step of bringing the molten metal and carbon material into contact by the casting step;
In the contacting step, when the contact area (mm ² ) of the molten metal with respect to the carbon material is S and the contact time (sec) between the carbon material and the molten metal is T, the product of the contact area and the contact time S × T The manufacturing method of the casting material of the magnesium alloy whose is 5.0 * 10 < ⁹ > (mm < ² > * sec) or more.   2. The method for producing a magnesium alloy cast material according to claim 1, wherein in the contacting step, a temperature of the carbon material brought into contact with the molten metal is 600 ° C. or more.   The method for producing a magnesium alloy cast material according to claim 1, wherein the contact time T is 10,000 sec or more. Applying the melting step in a melting furnace composed of a material other than the carbon material;
A holding step of temporarily storing the molten metal from the melting furnace in a holding furnace composed of the carbon material,
The manufacturing method of the cast material of the magnesium alloy of any one of Claims 1-3 with which the said contact process is given at the said holding process.   5. The method for producing a magnesium alloy cast material according to claim 1, wherein the content of the aluminum in the magnesium alloy is 1% by mass or more and 12% by mass or less.   The method for producing a magnesium alloy cast material according to claim 5, wherein the magnesium alloy contains aluminum in an amount of 8.3 mass% to 9.5 mass% and zinc in an amount of 0.5 mass% to 1.5 mass%. .   A cast material of a magnesium alloy obtained by the method for producing a cast material of a magnesium alloy according to any one of claims 1 to 6.   A wrought material of a magnesium alloy obtained by plastic working the cast material of the magnesium alloy according to claim 7.   A molded product of a magnesium alloy obtained by press-molding the expanded material of the magnesium alloy according to claim 8.