JP2011074469A - Method for producing silicon added magnesium alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily producing a magnesium alloy which has improved various qualities of material including mechanical properties, with a high degree of reliability, by adding a silicon component to a magnesium alloy as an additive component for improving the qualities of material. <P>SOLUTION: The method for producing the magnesium alloy to which the additive component for improving the quality of material is added in a production step includes: a silicon addition step of adding silicon to the magnesium alloy as the additive component; and a particle dispersion step of controlling the Mg<SB>2</SB>Si compound which is produced in the silicon addition step, so as to allow Mg<SB>2</SB>Si particles to have particle sizes of 40 μm or less. The amount of the silicon to be added in the silicon addition step is controlled so as to be in a range of 0.1-15.0 mass% in terms of a content rate of silicon with respect to the mass of the magnesium alloy to be produced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a magnesium alloy to which silicon is added.

  Magnesium alloys are the lightest among practical metals, are excellent in machinability and plastic workability, and have high specific strength, and are therefore used as materials for aircraft and automobiles. However, ordinary magnesium alloys have problems in heat resistance and flame retardancy even if the mechanical strength is increased by heat treatment. In addition, a so-called flame retardant magnesium alloy (magnesium alloy having a high ignition point) to which calcium is added has a problem that mechanical strength is lowered when heat treatment is performed.

On the other hand, a method for adding silicon (chemical formula: Si) to a magnesium alloy to improve its properties is known. For example, Japanese Patent Application Laid-Open No. 63-109138 discloses a technique in which silicon is added to a magnesium alloy and fine intermetallic compounds such as Mg ₂ Si are dispersed in the magnesium alloy matrix.

  Patent Document 2 (Japanese Patent Laid-Open No. 2-47238) discloses a technique for improving vibration damping characteristics by adding 0.1 to 1.0 mass% of silicon to a magnesium alloy.

  Patent Document 3 (Japanese Patent Laid-Open No. 9-1557829) discloses a technique for adding 0 to 17% by mass of silicon to a magnesium alloy to form a good nitriding phase.

JP 63-109138 A JP-A-2-47238 JP 9-1557829 A

  However, the technique disclosed in Patent Document 1 has a silicon content in the range of 0.2 to 1.5 mass%, and is limited to an extremely low range. Furthermore, the technique disclosed in Patent Document 1 relates to an alloy having a very limited range including magnesium, aluminum, manganese, and titanium in a specific range. That is, the technique disclosed in the cited document 1 sets a plurality of additive components added to magnesium within a specific range based on a standard or standard of a magnesium alloy, for example, and combines them. It is formed by doing.

  The technique disclosed in Patent Document 2 (Japanese Patent Application Laid-Open No. 2-47238) has been limited to the improvement of the vibration damping characteristics. Furthermore, the technique disclosed in Patent Document 2 is related to an alloy having a very limited range, in which various components are combined with magnesium in a specific range, as in Patent Document 1.

  The technique disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 9-1557829) was limited in its effect to improvement of the formation state of the nitriding phase. Furthermore, the technique disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 9-1557829) is a technique related to an aluminum alloy. When magnesium is included in this technique, the range further includes various components within a specific range. Regarding the limited alloy, this point was the same as the technique disclosed in the cited document 1.

  In addition, alloys such as magnesium alloys tend to have various changes in mechanical properties and thermal properties when different components are contained. Usually, the manufacturing process is specified in detail for the manufacture and improvement of alloys. There is a need. For example, with regard to the additive component added to improve the mechanical properties, the addition amount and the improvement effect of the magnesium alloy material can be obtained in a wide range, for example, a wide range of 1 to 15%, as a clear correlation. No additional ingredients are known. Furthermore, some inspections require a long period of time to confirm that the obtained alloy is suitable for the intended use.

  The present invention has been made in view of the above problems, and its purpose is to increase the magnesium alloy in which various materials are improved, including mechanical properties, by adding a silicon component as an additive component for improving the material. The object is to provide a reliable and easy manufacturing method.

The invention according to claim 1 for solving the above-mentioned problem is a method for producing a magnesium alloy in which an additive component for improving the material is added in the production stage, wherein a silicon addition step of adding silicon as the additive component, and the silicon addition step A particle dispersion step in which the resulting Mg ₂ Si compound is Mg ₂ Si particles having a particle size of 40 μm or less, and the amount of silicon added in the silicon addition step is the inclusion of silicon relative to the mass of the magnesium alloy to be produced It is characterized by being adjusted in the range of 0.1 to 15.0% by mass in terms of rate.

The bonding force between magnesium and silicon is strong. For example, when silicon is added to solid magnesium and solidified, a compound represented by the chemical formula Mg ₂ Si is formed. When this Mg ₂ Si (magnesium silicite) is dispersed in the material in the form of fine particles, various materials such as mechanical properties are greatly improved compared to the case where no Mg ₂ Si particles are present. Is done. This improved effect is due to the physical configuration in which fine Mg ₂ Si particles are dispersed in the material. Therefore, while maintaining this physical configuration, the silicon content is changed in a wide range of 0.1 to 15% by mass, and thus the dispersion concentration of fine Mg ₂ Si particles is changed, and the mechanical properties and the like are changed. It improves the intended properties of the product to the desired range. Therefore, the present invention can be easily applied to the improvement of a wide range of magnesium alloys (magnesium alloy materials) without being limited by the types and amounts of other components included in magnesium.

The invention of claim 2 is characterized in that, in the particle dispersion step, the particle size of the Mg ₂ Si particles is in the range of 0.5 to 20 μm. The finer the Mg ₂ Si particles, the higher the effect of improving the mechanical properties and thermal properties of the alloy. Thus, a particle size of Mg 2 _Si particles is limited to a range where the effect appears remarkably.

According to a third aspect of the present invention, the amount of silicon added in the silicon addition step is adjusted in the range of 2.0 to 15.0 mass% in terms of the silicon content relative to the mass of the magnesium alloy to be produced. It is characterized by that. Thereby, the dispersion concentration of Mg ₂ Si particles in the alloy is limited to a range in which the effect is remarkably exhibited.

According to the present invention, Mg ₂ Si particles are dispersed in a material (magnesium alloy) as particles having a particle diameter of 40 μm or less, thereby greatly improving the material properties, particularly mechanical strength, for example, hardness (hardness). The obtained alloy material can be easily obtained.

It is a photograph which shows the structure | tissue of a test piece whose silicon content is 5%. It is a photograph which shows the structure | tissue of a test piece whose silicon content is 10%. It is a photograph which shows the structure | tissue of a test piece whose silicon content is 15%.

  The present invention will be described below using embodiments. The present invention is a method for producing a magnesium alloy in which silicon is added as an additive component for improving the material at the production stage. And the magnesium alloy by which various material characteristics, such as mechanical strength, were improved compared with the magnesium metal material or magnesium alloy material manufactured without adding silicon. In the present invention, an alloy means a mixture of two or more metals, and an alloy containing nonmetallic elements such as carbon and silicon in addition to metals. The alloy structure includes a solid solution, a eutectic (eutectic mixture), a compound (intermetallic compound), or a material in which they coexist. Therefore, a material in which silicon is mixed with magnesium is also included in the magnesium alloy.

  Here, magnesium is a metal whose element symbol is represented by Mg. In the present invention, as a magnesium alloy to be improved in material properties, in principle, all magnesium alloys are used. In the present invention, examples of magnesium alloys to be improved in material properties include casting magnesium alloys, for example, Mg-Al alloys, for example, ASTM standard, AM100A, Mg-Al-Zn alloys, for example, ASTM standard, AZ63A, AZ81A, AZ91C, AZ91A, AZ91B, AZ92A, Mg-Zn-Zr alloy, for example, ASTM standard, ZK51A, ZK61A, Mg-Zn-RE alloy, for example, ASTM standard, EZ33A, ZE41A, Mg-Th alloy, for example, ASTM standard, HK31A, HZ32A, ZH62A, Mg-Ag alloy, for example, ASTM standard, QE22A, Mg-Al-Si alloy, for example, ASTM standard, AS41A, Mg-Zr alloy, for example, ASTM standard, K1A It is shown.

  In the present invention, other examples of the magnesium alloy to be improved in material properties include a magnesium alloy for extension, an Mg-Mn alloy (M1A), for example, for an extruded bar, ASTM standard, AZ31A ( MB1), AZ61A (MB2), AZ80A (MB3), M1A, ZK60A (MB6), for extruded tubes and profiles, ASTM standard, AZ31B (MT, MS1), AZ61A (MT, MS2), M1A, ZK60A ( MS6) B, C, AZ61A, AZ80A, Mg-Zn-Zr alloy, ASTM standard, ZK60A, Mg-Zn-rare earth element alloy, ASTM standard, ZE10A, Mg-Th Examples of alloys are HM21A, HM31A, and HK31A according to ASTM standards. These magnesium alloys are described in, for example, “Non-ferrous materials”, Lecture / Modern Metallographic Materials 5, Second Printing, Japan Institute of Metals, pages 110-117. The present invention can also be applied to the improvement of the material of a flame retardant alloy (alloy having a high ignition point) in which Ca is added to the magnesium or magnesium alloy described above. In this case, the magnesium alloy preferably contains Ca in the range of 0.1 to 15.0% by mass. Furthermore, the present invention is also suitable for improving the material of heat-resistant magnesium alloys, such as Mg-Al-Zn-Mn heat-resistant alloys and alloys obtained by adding 0.1 to 4% of Ca to such alloys. . In the present invention, the heat-resistant alloy means a metal material that maintains strength, corrosion resistance, creep resistance, or pressure resistance, fatigue resistance, and wear resistance depending on applications at high temperatures.

  In this invention, the addition process which adds silicon (element symbol Si) as an additional component is performed. Silicon may be added as a compound with other substances, or silicon alone may be added.

  In the addition step, silicon may be added to the raw material for production in the solid state, or may be added to the raw material for production in the liquid state (molten state) and further in the semi-molten state. Here, the raw material for production is a raw material used for forming the above-described magnesium or magnesium alloy, and examples thereof include magnesium, aluminum, and zinc.

Next, a description will be given of a particle dispersion step in which the Mg ₂ Si compound generated in the silicon addition step is Mg ₂ Si particles having a particle size of 40 μm or less. This particle dispersion step can be performed using an atomizing method such as a liquid atomizing method or a gas aromatizing method. The atomization method is a method in which molten metal is ejected at a high speed and the ejected molten metal is rapidly cooled. A liquid atomizing method uses a liquid, for example, water as a cooling means, and a gas atomizing method uses a gas. A product is usually obtained as a metal powder. In the case of the gas atomization method, the molten metal is usually sprayed. When solidified magnesium or magnesium alloy containing silicon is solidified by the atomizing method, the compound represented by Mg ₂ Si (magnesium silicite) is almost uniform inside in the state of fine particles, that is, Mg ₂ Si particles. A complex dispersed in is obtained. Here, the Mg ₂ Si particles dispersed and present in the obtained material mean a minute constituent part substantially composed of the Mg ₂ Si compound present in the material. Therefore, in one embodiment of the present invention, the component-added material produced according to the present invention includes Mg ₂ Si particles finely and substantially uniformly dispersed therein and a matrix that is another component of the material. Is a complex consisting of The atomizing method described above may be referred to as a “thermal spraying method”. The thermal spraying method is described in “Nonferrous Materials”, Lecture / Modern Metallurgy Materials, Second Printing, Japan Institute of Metals, pp. 219-222.

The diameter (particle diameter) of the Mg ₂ Si particles can be adjusted to a desired range by appropriately setting the conditions of the atomizing method, for example, the rapid cooling rate of the molten metal. In the present invention, the particle diameter of the Mg ₂ Si particles is 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less, for example, 1 to 10 μm. In the present invention, it is also possible to control the particle size distribution of Mg ₂ Si particles to be a narrow distribution. In this case, the average particle size of Mg ₂ Si particles (magnesium silicite particles) is preferably 40 μm or less, preferably It is also possible to adjust to a range of 20 μm or less, more preferably 10 μm or less, for example, 1 to 10 μm. Note that the description of the “particles” of the Mg ₂ Si particles and the particle diameter are the same in other forms described below.

When a composite is produced by the atomizing method, the Mg ₂ Si particles are almost spherical, which is preferable for obtaining a composite having excellent mechanical properties. The composite obtained by the atomization method is usually obtained in a powder state. The material (composite) in a powder state is molded into a product by, for example, a sintering method in which sintering is performed in a mold. This product is later finished if desired. In the present invention, the amount of silicon added can be adjusted in the range of 0.1 to 15.0 mass%, preferably 2.0, in terms of the silicon content relative to the mass of the magnesium alloy to be produced. It is adjusted in the range of ˜15.0 mass%. Here, even if the content of the silicon component is higher than 15%, no significant improvement in mechanical properties or the like is observed. Conversely, various problems occur in processing at the manufacturing stage. For example, the viscosity of the molten alloy increases and the processability deteriorates. Further, when the content of silicon in the material is less than 0.1% by mass, a great effect of adding silicon cannot be expected.

  As another method for performing the particle dispersion step, there is exemplified a method of adding silicon, for example, as a powder to magnesium or a magnesium alloy melted at a high temperature and stirring. In this case, the temperature of molten magnesium (alloy) is preferably in the range of 750 ° C to 900 ° C.

  As still another method for performing the particle dispersion step, a method in which plastic processing is performed on a material in which silicon is added to magnesium or a magnesium alloy is exemplified. In this case, the material subjected to the plastic working process can be manufactured by, for example, a casting method. Examples of the plastic processing include extrusion, rolling, punching, stamping, drawing, and forging. Moreover, it is preferable to set the temperature of the material at the time of plastic working to the range of 200-400 degreeC.

By this plastic working process, an intermetallic compound at a grain boundary, for example, magnesium silicite, is crushed into fine particles and dispersed in the matrix as Mg ₂ Si particles having the above-described dimensions. Then, the plastic working process can be performed so that the dispersion of the Mg ₂ Si particles in the material is substantially uniform.

Next, the effects obtained by the present invention will be described. According to the present invention, Mg ₂ Si particles are dispersed in a material (magnesium alloy) as particles having a particle size of 40 μm or less, preferably 20 μm or less, more preferably 10 μm or less, thereby making it possible to obtain characteristics of the material, particularly mechanical properties. An alloy material having greatly improved strength, for example, hardness (hardness) can be obtained. Here, when the content of silicon in the material is changed according to the present invention, the change in the silicon content appears as a change in the dispersion density of Mg ₂ Si particles present in a finely dispersed state in the material. .

Therefore, even if the silicon content is changed, the microscopic physical structure of the material, that is, the structure in which Mg ₂ Si particles are dispersed in a matrix substantially composed of magnesium or a magnesium alloy is changed. Maintained without. Therefore, by adjusting the amount of silicon added to the material, the dispersion concentration in the material of Mg ₂ Si particles having a predetermined particle size can be set to a desired material property such as mechanical strength, particularly desired hardness. It adjusts to the range obtained.

  Furthermore, the heat resistance of the base material is improved by adding silicon to magnesium or a magnesium alloy. Here, the improvement in heat resistance due to the addition of silicon is a characteristic that can be seen not only in magnesium alloys but also in cast steel (Hi-Si material) applied to exhaust system parts such as an exhaust manifold for automobiles.

  In particular, when the present invention is applied to the material improvement of a flame retardant magnesium alloy or a heat resistant magnesium alloy, it becomes possible to use a magnesium alloy improved to a desired mechanical property in a high temperature environment. Therefore, for example, the magnesium alloy manufactured according to the present invention can be applied to application fields that require high strength, heat resistance, and flame retardance such as parts of automobile engines, such as pistons. In addition, the basic performance as an automobile can be improved, such as weight reduction and lower vibration and noise by reducing the inertial force of the reciprocating part, and improved output and fuel consumption due to high compression ratio by improving heat transfer coefficient. . In addition, when the present invention is applied to the manufacture of pistons for engines, the following effects can be obtained: weight reduction, reduction of inertial force of the reciprocating motion part, reduction of vibration, noise reduction, improvement of anti-knock properties by improvement of heat transfer coefficient, ignition It can contribute to improvement of timing, output, fuel efficiency, and reduction of exhaust gas harmful component concentration.

  In addition, the magnesium alloy produced in the present invention can be applied as a structural member for aerospace computers, weather satellites, audios, and the like. In this case, under low pressure, vacuum conditions, or high temperature conditions, the heat dissipation effect is improved by improving the heat transfer coefficient, the vibration damping characteristics are improved by light weight and high rigidity, and the acoustic followability is improved by excellent damping characteristics Basic performance such as a speaker frame) can be improved.

  Flame retardant magnesium alloy (AMn602 base) was melted by changing the silicon content to 5%, 10% and 15%. The melted metal alloy was cast, and the obtained billet was extruded (pushing ratio 20). The hardness of the test piece obtained from the extruded material was measured. The test was performed on three types of test pieces in which the silicon addition amount was changed to 5%, 10%, and 15% for sample 1. Further, the same test and measurement were performed for Sample 2 whose alloy composition is different from Sample 1. And the hardness of the test piece whose silicon addition amount is 5% was set to 1, and the hardness of the test piece whose silicon content was 10% and 15% was compared.

  In the case of the result sample 1, the hardness increased by 25% and 38% for the material added with 10% and 15% silicon, respectively, with respect to the material added with 5% silicon.

  In the case of Sample 2, the hardness of the material added with 10% and 15% of silicon increased by 11% and 41%, respectively, with respect to the material added with 5% of silicon.

  The microscope picture (organizational chart) of the test piece of each silicon content of sample 1 is shown. 1 is a structural diagram of a test piece having a silicon content of 5%, FIG. 2 having a silicon content of 10%, and FIG. 3 having a silicon content of 15%.

  The magnesium alloy produced according to the present invention has excellent characteristics such as mechanical properties, heat resistance properties, flame retardancy, and the like, and is expected to be applied to pistons and the like that have not been conventionally applicable.

Claims (3)

A manufacturing method of a magnesium alloy in which an additive component for material improvement is added at the manufacturing stage,
A silicon addition step of adding silicon as the additive component;
A particle dispersion step in which the Mg ₂ Si compound produced by the silicon addition step is Mg ₂ Si particles having a particle size of 40 μm or less;
The amount of silicon added in the silicon addition step is adjusted in the range of 0.1 to 15.0 mass% in terms of the silicon content relative to the mass of the magnesium alloy to be produced. And how to. Wherein the particle dispersion step, the method according to claim 1, the particle size of the _Mg 2 Si particles, characterized in that it is in the range of 0.5 to 20 [mu] m.   The amount of silicon added in the silicon addition step is adjusted in the range of 2.0 to 15.0% by mass in terms of the silicon content relative to the mass of the magnesium alloy to be produced. .

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