JP2008536005A - Magnesium alloy added with misch metal, magnesium alloy processed material added with misch metal, and magnesium alloy processed material manufactured thereby - Google Patents

Abstract

The present invention relates to a magnesium alloy to which misch metal is added, a method for producing a magnesium alloy processed material to which misch metal is added, and a magnesium alloy processed material to be manufactured by the same. Magnesium added with high melting point eutectic phase or multi-phases to form a rigid network structure or dispersed phase to suppress deformation of magnesium substrate at high temperature and maintain high strength An alloy is provided.
The magnesium alloy to which misch metal is added according to the present invention is represented by the general formula Mg _100-xyz A _x B _y C _z , where A represents zinc (Zn) or aluminum (Al) element, and B represents Misch metal, element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P), silver (Ag) , Strontium (Sr), or two or more elements selected, wherein x, y, and z are 0 at% ≦ x ≦ 6 at%, 0.8 at% ≦ y ≦ 7 at%, and 0 at% ≦, respectively. z ≦ 2 at%.

Description

  The present invention relates to a magnesium alloy to which a misch metal having excellent mechanical properties is added by adding a large amount of misch metal to magnesium and having a strong network structure or a dispersed phase even at high temperatures, and to heat this magnesium alloy. Alloy processed material manufacturing method in which second-phase or multi-phases, which are solidified structures, are made into particles by hot pressing and hot rolling, and the crystal grains of the matrix are made ultrafine, and thereby The present invention relates to a processed magnesium alloy material.

  Today, there is an absolute demand for weight reduction of parts due to the growing interest in environmental and energy saving problems globally, solving the problem of environmental pollution caused by carbon dioxide generated during transportation through roads, aviation and railways. There is an increasing demand to reduce the weight of parts or finished products in order to save transportation fuel. In this situation, magnesium alloy has the density of 2/3 of aluminum alloy and 1/5 of iron alloy, which is the lightest commercial alloy. ing. In addition, because it has excellent specific strength, rigidity, vibration absorption capability, workability, dimensional safety, and electromagnetic wave shielding effect, the magnesium alloy plate material is an exterior material for electronic communication products such as mobile communications and notebook computers. It is a fact that usage is expanding.

  Generally, high-temperature structural magnesium alloys are roughly classified into two types, namely, casting alloys that are used without heat treatment and sand-type casting alloys that have improved high-temperature characteristics by depositing a second phase in the substrate.

  Due to the characteristics of the manufacturing process of casting alloys, when the molten metal passes through the gate of the mold and enters the cavity, a lot of vortex flows are generated and the product has many blowholes. Such residual pores are usually not subjected to heat treatment because they cause blisters on the product surface when heat treatment including solution treatment is performed later. Therefore, the magnesium-aluminum (Mg-Al) -based AZ91 alloy, which is currently widely used in casting alloys, is exposed to high temperatures (150 ° C or higher) such as automobile transmission cases because of its high temperature characteristics, particularly low creep resistance. There is a disadvantage that is difficult to apply to the parts to be. When aluminum (Al) is added to magnesium (Mg), the strength at normal temperature and the fluidity of the molten metal may be improved, but the Mg17Al12 phase is formed and the creep resistance at high temperature is reduced. To be generated. In order to overcome this, rare earth elements are added, or calcium (Ca), silicon (Si), strontium (Sr), etc. are added as disclosed in US Pat. No. 6,264,763. However, there are still limits to practicality in terms of productivity, mechanical properties including high temperature creep characteristics, corrosion resistance, and cost.

  The sand casting mold alloy is an alloy in which the second phase is precipitated in the substrate by heat treatment to improve the high temperature strength and heat resistance, and a relatively healthy casting can be obtained. For this purpose, the element added must have a solid solubility in the magnesium substrate that varies greatly depending on the temperature, and the solid solubility must be maintained even at a temperature of 200 ° C. or higher, which is mainly used. Silver (Ag), thorium (Th), yttrium (Y), neodymium (Nd), scandium (Sc), etc. are used as the main additive elements in sand casting alloys, but they are very expensive or radioactive materials Has been used in a limited manner only in places where the performance is more specific than the unit price of the material.

  On the other hand, conventionally, there has been a technical problem in forming a magnesium alloy material. Basically, magnesium alloy is a hexagonal close-packed structure, and the slip system required for plastic processing is limited, so it is very difficult to mold and manufacture products at room temperature. The molded product must be manufactured.

  As described above, improvement of formability is absolutely necessary for the development of intermediate materials and products of magnesium alloy, but this is best achieved by making the crystal structure of magnesium alloy fine and improving the stretch ratio. It is an effective method. In addition, fine grained alloys must be possible in an industrial manner in the manufacturing process. Although the demand for magnesium plate is gradually increasing, it is not effective to produce a magnesium alloy plate having the required microstructure in the commercially available magnesium alloys.

  In the case of the existing AZ31 alloy, the rolling reduction ratio must be increased in order to refine the crystal grains, but in this case, the thickness reduction rate is limited by the occurrence of serious cracks. There is a problem that miniaturization is limited. That is, in the case of such a solid solution alloy, the source capable of causing recrystallization inside the material is limited, and there is a limit to refinement of crystal grains.

  The present invention has been devised in order to solve the conventional problems as described above, and an object of the present invention is to add a large amount of misch metal to magnesium to obtain a high melting point eutectic phase. Alternatively, the formation of a solid network structure or dispersed phase in multi-phases suppresses deformation of the magnesium substrate at high temperatures, and further addition of other elements enhances precipitation / solid solution in the substrate structure. In other words, the neckwork structure is strengthened to provide an alloy to which a misch metal added with excellent mechanical properties that maintains high strength at high temperatures is added.

  Another object of the present invention is that the second phase or multiphase magnesium alloy to which misch metal is added is subjected to hot extrusion, a hot rolling process, and a second phase or multiphase (multiphase) which is a solidified structure. The present invention provides a method for producing a magnesium alloy processed material in which crystal grains are refined by recrystallizing a matrix by recrystallizing (-phases).

  Another object of the present invention is to exhibit a mechanical property having high strength and toughness in a room temperature region where the alloy is actually used by having a fine grain structure, and stretching at the temperature at which it is actually formed. The present invention provides a magnesium alloy processed material having an excellent rate and improved formability.

The magnesium alloy to which the misch metal according to the present invention is added to achieve the above object is represented by the general formula Mg _100-xyz A _x B _y C _z , where A is zinc (Zn) or aluminum (Al). B represents misch metal, element C represents silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus ( P), silver (Ag), strontium (Sr), or two or more elements selected, wherein x, y, and z are 0 at% ≦ x ≦ 6 at% and 0.8 at% ≦ y, respectively. ≦ 7 at%, 0 at% ≦ z ≦ 2 at%.

  Further, the misch metal in the magnesium alloy to which the misch metal according to the present invention is added is a didymium misch metal or a cerium misch metal.

  Here, the didymium misch metal has a rare earth alloy composition containing Nd (neodymium) and Pr (praseodymuim).

  Here, the cerium (Ce) -based misch metal includes 45 wt% ≦ Ce ≦ 65 wt%, 20 wt% ≦ La ≦ 30 wt%, 5 wt% ≦ Nd ≦ 15 wt%, 0 wt% ≦ Pr ≦ 10 wt%. And

  The magnesium alloy to which the misch metal according to the present invention is added further contains 2 at% or less calcium.

The method for producing a magnesium alloy processed material to which the misch metal of the present invention is added is expressed by a general formula Mg _100-xyz A _x B _y C _z , wherein A represents zinc (Zn) or aluminum (Al) element. B is misch metal, element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P) , Silver (Ag), strontium (Sr), or two or more elements, wherein x, y and z are 0 at% ≦ x ≦ 6 at% and 0.8 at% ≦ y ≦ 7 at, respectively. %, 0at% ≦ z ≦ 2at% of the magnesium alloy composition is melt-cast, and the cast material is hot-pressed to crystallize the particles other than magnesium in the cast material by dispersing, dispersing, and recrystallizing the substrate. The method includes the step of refining the grains.

  Moreover, the manufacturing method of the magnesium alloy processed material to which the misch metal of the present invention is added further includes a step of hot rolling the hot extruded material to produce a plate material.

  Further, in the method for producing a magnesium alloy processed material to which the misch metal of the present invention is added, the hot pressing step is performed in a temperature range of 350 to 450 ° C. and a pressing condition of a cross-section reduction ratio of 5 to 80: 1.

  In the method for producing a magnesium alloy processed material to which the misch metal of the present invention is added, the hot rolling step is performed in a temperature range of 350 to 500 ° C. under rolling conditions with a single rolling reduction of 25 to 50%.

In addition, the magnesium alloy processed material to which the misch metal according to the present invention is added is represented by the general formula Mg _100-xyz A _x B _y C _z, where A represents a zinc (Zn) or aluminum (Al) element, Said B is misch metal, element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P), silver (Ag), one or more elements selected from strontium (Sr), wherein x, y, and z are 0 at% ≦ x ≦ 6 at%, 0.8 at% ≦ y ≦ 7 at%, The step of melting and casting a composition satisfying 0 at% ≦ z ≦ 2 at%, and hot extruding the cast material to granulate and disperse phases other than magnesium in the cast material, and recrystallize the substrate to refine the crystal grains And a step of hot-rolling the hot extruded material to produce a processed material.

  Moreover, the processed magnesium alloy material to which the misch metal is added according to the present invention is characterized in that the phase size other than magnesium is 20 μm or less.

  Moreover, the magnesium alloy processed material to which the misch metal according to the present invention is added is characterized in that elements other than magnesium are included from the solid solution limit to the eutectic point or the hypereutectic region.

  The structure of the magnesium alloy to which the misch metal is added according to the present invention will be described in detail.

The magnesium alloy to which misch metal is added according to the present invention is represented by the general formula Mg _100-xyz A _x B _y C _z , where A represents zinc (Zn) or aluminum (Al) element, and B represents Misch metal, element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P), One or two or more elements selected from silver (Ag) and strontium (Sr), wherein x, y and z are 0 at% ≦ x ≦ 6 at% and 0.8 at% ≦ y ≦ 7 at%, respectively. 0 at% ≦ z ≦ 2 at%.

  In the magnesium alloy to which the misch metal is added according to the present invention, when solidified by casting, the magnesium base solid solution (alpha magnesium) forms a matrix structure, and the second phase is crystallized by the misch metal (element B) to form a magnesium substrate. To form a complex network or dispersed phase. This structure is solid at high temperature and has excellent mechanical properties, and the third phase can also be generated by the elements A and C group, which mainly forms solid solution / precipitation of magnesium matrix structure or network structure. Strengthen to improve mechanical properties.

  In the case of aluminum (Al) of the element A group mentioned above, if it exceeds 5 at% and added like element B, the Mg17Al12 phase is formed on the alpha magnesium substrate and the mechanical properties are reduced, so that it is less than 5 at%. It is desirable to restrict with.

  Zinc (Zn) has a maximum solid solution limit of 2.4 at% in magnesium (Mg) at 340 ° C. However, when considering the amount of solid solution in the second phase, element A The addition range of the group is desirably limited to 5 at% or less.

  According to the magnesium alloy to which misch metal is added according to the present invention, the Mg-Misch meta system contains aluminum (Al) and zinc (Zn) in the element A group having solid solubility in magnesium. (multi-phases) can be obtained. Although the misch metal added here is composed of elements having atomic numbers 57 to 71, a didymium misch metal or a cerium misch metal is added. The didymium-based misch metal has a rare earth alloy composition including Nd (neodymium) and Pr (praseodymuim). It means a commercialized misch metal alloy having a main composition range of ≦ 15 wt%, 0 wt% ≦ Pr ≦ 10 wt%, and other miscellaneous elements in addition to the characteristics of crystallizing misch metal. This misch metal (element B) forms a strong network structure or dispersed phase at a high temperature to improve the corrosion resistance and the fluidity of the melt. When the addition range of this misch metal (element B) exceeds 7 at%, the two-phase fraction of brittleness is increased and the material is not stretched at room temperature, which is not desirable. Therefore, in the present invention, the addition range of element B is limited to 7 at% or less.

  In the magnesium alloy to which the misch metal is added according to the present invention, the element C group (Si, P, B, Mn, Sr, Y, Ni, Cu, Sn, Ag) are added. At this time, the additive element C group is an element that has strong affinity with magnesium (Mg) or misch metal, but when added in a small amount, it consists of elements that can improve the mechanical properties while maintaining the network structure . Typical examples are phosphorus (P), boron (B), manganese (Mn), strontium (Sr), yttrium (Y) and nickel (Ni), copper (Cu), tin (Sn), silver (Ag ). Therefore, the addition range is strengthened while maintaining a strong network structure at high temperature, or limited to 2 at% or less so as to expect the effect of precipitation / solid solution strengthening on the substrate structure.

  In addition, a small amount of calcium (Ca) is added to the magnesium alloy to which the misch metal according to the present invention is added, so that the magnesium alloy composition can be dissolved and cast in the atmosphere without using a protective gas or a solvent. Can do. The range of addition is limited to 2 at% or less, which can provide a useful effect of calcium (Ca).

  Next, preferred embodiments of the magnesium alloy to which the misch metal of the present invention having the above-described structure is added will be described in detail.

[Example 1]
A molten magnesium alloy composition as disclosed in the following Table 1 is prepared, and a cast material is obtained by a casting method. For casting, heat the carbon crucible at 700 ° C in an electric induction heating furnace to melt magnesium, add other additives to make molten alloy, and put the molten alloy into the casting frame preheated at 120 ° C. To produce castings.

In the composition specified in Table 1, B represents at% of cerium-based misch metal. The second phase produced by adding element B is the Mg ₁₂ Ce phase, and FIG. 1 shows that the alpha magnesium structure and the Mg ₁₂ Ce phase form a network structure in a scanning electron micrograph of Alloy 3. . The structure of this network structure is strong at high temperatures and suppresses the deformation of the alpha magnesium structure and exhibits high strength at high temperatures. Therefore, increasing the amount of element B increases the Mg ₁₂ Ce phase and increases the yield and tensile strength at room and high temperatures. In the case of Alloy 10, not only the second phase of the Mg ₁₂ Ce phase but also the third phase is crystallized in the form of an aluminum (Al) compound to improve the mechanical characteristics.

  Therefore, when compared with the existing magnesium heat-resistant alloy, the magnesium alloy to which the misch metal according to the present invention is added has a two-phase or three-phase network structure in which the strength change due to temperature change is very small. Thus, it is possible to replace the heat-treated sand-type cast heat-resistant magnesium alloy mainly used at 200 ° C. or higher and the magnesium alloy produced by the die casting method.

The E _corr value shown in Table 1 is a value obtained by measuring the potential of an open circuit in a 3.5 wt% sodium chloride (NaCl) solution for 3 hours, relative to the existing heat-resistant alloy (AZ91) to be compared. Corrosion resistance was confirmed. As a result, it can be seen that the corrosion resistance is increased while the amount of element B is increased.

[Example 2]
Fig. 2 is a photograph of molten metal in which 2wt% calcium (Ca) was added to Alloy 9 in Table 1 and dissolved in the atmosphere. By adding calcium (Ca) to the magnesium alloy composition (Alloy 9), magnesium alloy in the atmosphere It shows that the composition can be melted and cast. As can be seen from FIG. 2, when the magnesium alloy composition is dissolved in the atmosphere, it can be confirmed that a thick oxide is not formed on the surface of the molten metal.

  [Example 3]

In the magnesium alloy to which the misch metal is added according to the present invention, the Mg ₁₂ Ce phase formed by adding a cerium (Ce) based misch metal to magnesium (Mg) is an intermetallic compound and is brittle as described above. have. Therefore, when the fraction of the Mg ₁₂ Ce phase in the alloy is higher than that of the magnesium substrate, the stretch ratio is lowered. Therefore, in this example, an attempt was made to improve the characteristics by adding a specific element. In Example 3, Alloy ₁₂ having the highest fraction of the Mg ₁₂ Ce phase in the composition presented in Table 1 was selected, and the degree of brittleness of the second phase due to the additive element was investigated. As shown in Table 2, a molten magnesium alloy composition was prepared, a cast material was obtained by a casting method, and a Vickers hardness test was performed. At this time, the applied press-fit load was investigated while changing from 100 g to 1000 g. Table 2 shows that the hardness value increases by adding elements such as nickel (Ni), copper (Cu), tin (Sn), aluminum (Al), manganese (Mn), silicon (Si) to Alloy12. Show. In addition, it was confirmed that the degree of occurrence of microcracks appearing around the press-fitting marks on the surface of the material was reduced or eliminated when the hardness test was performed. In Table 2, the increase in the hardness value and the change in the degree of occurrence of cracks are caused by the additive elements strengthening the network frame structure. Thus, according to the embodiment of the present invention, the additive element C (Si, P, B, Mn, Sr, Y, Ni, Cu, Sn, Ag) group is added to the magnesium alloy to which the misch metal of the present invention is added. It can be seen that the mechanical properties increase when elements having strong affinity with magnesium (Mg) or cerium-based misch metal are added.
[Example 4]

Table 3 shows the stretch ratio obtained by adding Al to the alloy composition (Alloy2, Alloy6) presented in Example 1 and through a tensile test. As shown in Table 3, it can be seen that the stretch ratio is increased by a minute amount change of Al. However, when Al is added in excess of 4 at%, an Mg ₁₇ Al ₁₂ phase is generated in the magnesium substrate without maintaining a network structure capable of maintaining high strength at high temperatures, which is undesirable.

  As described above, it is confirmed that the example of the magnesium alloy to which the misch metal of the present invention is added is a magnesium alloy for high-temperature structure whose mechanical characteristics and corrosion resistance are greatly improved as compared with the existing heat-resistant magnesium alloy. Can do.

  Next, the magnesium alloy processed material manufactured by the magnesium alloy to which the misch metal according to the present invention is added will be described.

  In the present invention, a processed material is manufactured by extruding and rolling a magnesium alloy cast material to which the misch metal having the above-described composition is added. In general, magnesium alloys cannot ensure workability at room temperature, so high-temperature processing is performed to obtain sound processed materials, and the processing temperature of cast materials ensures the soundness of the processed materials through experiments. Set as much as possible. In the case of extrusion, the cast material was preheated at 350 to 500 ° C., and then the extrusion was performed at the same temperature. As the pressing conditions, a pressing ratio of 6.5: 1, a pressing die angle (die angle) of 180 °, and a ram speed of 2 cm / min are applied.

  Through such extrusion, an applied product with improved strength and stretch ratio can be obtained by inducing second-phase dispersion and recrystallization on the matrix structure. Further, when a rolled product having a thickness of 1 mm is obtained by repeatedly rolling from 400 ° C. to a thickness shrinkage of 40%, an effect such as extrusion can be obtained.

  The grain refinement mechanism of the magnesium alloy to which the misch metal of the present invention is added is a dynamic recrystallization phenomenon in which new grain nuclei are generated inside the structure during hot working of the magnesium alloy. In the case of a magnesium alloy in which particles are distributed in large quantities, the recrystallization source is increased and the grain refinement becomes very efficient. In order to maximize such characteristics, magnesium containing a volume fraction of a phase other than magnesium in the matrix from 5% to 50% is first manufactured through a casting method, and the phases present in the interior are produced. Is effectively dispersed in the magnesium substrate through hot extrusion, or hot extrusion and hot rolling processes, and dynamic recrystallization is effectively generated by these dispersed phases to produce crystals. Maximize grain refinement.

More specifically, the processed magnesium alloy material to which the misch metal is added according to the present invention is expressed by the general formula Mg _100-xyz A _x B _y C _z, where A is zinc (Zn) or aluminum (Al ) Element, B is misch metal, element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus One or more elements selected from (P), silver (Ag), and strontium (Sr), and x, y, and z are 0 at% ≦ x ≦ 6 at% and 0.8 at% ≦ y, respectively. ≦ 7 at%, 0 at% ≦ z ≦ 2 at%. Although the misch metal added here is composed of elements having atomic numbers 57 to 71, a didymium misch metal or a cerium misch metal is added. Didymium-based misch metal is a rare earth alloy composition containing Nd (neodymium) and Pr (praseodymuim). %, 0 wt% ≦ Pr ≦ 10 wt% means a commercialized misch metal alloy having a main composition range of 15 wt% or more in addition to the characteristic that misch metal is crystallized.

  Such additive elements to Mg, that is, elements that can form an eutectic, specifically Al, Si, Ag, Ca, Ni, Cu, Zn, Y, Sn, La, Ce, Pr, When at least one of Nd, Ce rich-misch metal, and Didymium rich-misch metal is added, a magnesium alloy containing a large amount of the phase described above is produced by a casting method. can do. As a result of hot-pressing this, the cast structure is destroyed and the phases other than magnesium are dispersed while being granulated, thereby effectively generating a dynamic recrystallization phenomenon, which causes the crystal grains to be dispersed. Refine. Such a hot pressing method can effectively destroy and disperse particles generated by impure elements which are inevitably added during casting of the magnesium alloy. The extruded material can be further stabilized.

  When the extruded material is hot-rolled, it is possible to produce a magnesium alloy plate in which a large number of different phases exist in the magnesium substrate. In general, when a cast material having a large amount of phase in a magnesium alloy is hot-rolled, it is impossible to roll because the phases are broken and acted by a crack source. In the case of extrudates that have been granulated and dispersed, the crystal grains have already been refined, and even if cracks occur, the size is limited by the particle size, which greatly affects hot rolling. There is no hot rolling. In addition, even if the temperature of the rolling process is increased in order to make the rolling process effective, there is an advantage that rolling is easy while the growth of crystal grains is hindered by a large amount of distributed particles.

  Next, a preferred embodiment of a method for producing a magnesium alloy processed material to which misch metal is added according to the present invention will be described.

  In the following examples, a processed material magnesium alloy near the eutectic point, near the hyper-eutectic, near the hypo-eutectic, near the solid solution limit. Extruded material and plate material production will be described.

[Example 5]
In this example, an extruded material and a plate material are manufactured using an Mg—Ce-based Misch metal-Zn alloy in the vicinity of an eutectic point.

  A slab is prepared by mixing with Mg (93.75 at%)-Ce-based Misch metal (4.25 at%)-Zn (2.0 at%) in an atomic weight percentage and melt casting. FIG. 3 is a photograph of the cast structure of this alloy. In order to effectively distribute the eutectic phase and obtain a fine-grained magnesium substrate, hot extrusion was performed at a temperature of 450 ° C., an extrusion speed of 2 mm / second, and a cross-section reduction ratio of 6: 1. .

  FIG. 4 is a photograph of the microstructure that was hot-pressed in this example. As disclosed, the inner structure has no cracks and the average crystal grain size is 14 μm or less and is extremely fine. In general, a magnesium alloy having no particles cannot obtain such a fine crystal grain size through a single hot pressing process.

  Further, a magnesium alloy plate was manufactured by rolling from the extruded material at a temperature of 400 ° C. and a roll temperature of 100 ° C. at a rolling reduction of 40%. FIG. 5 shows no fine cracks as disclosed in the microstructure photograph of the rolled plate material, and the average crystal grain size is 8 μm and is very fine.

A photograph of a test piece, which is a result of a high-temperature tensile test of the plate material thus manufactured, is shown in FIG. The high temperature tensile test was performed at a temperature of 500 ° C. with a deformation ratio of ¹ × 10 ⁻³ s ⁻¹ , ¹ × 10 ⁻² s ⁻¹ , ¹ × 10 ⁻¹ s ⁻¹ , ¹ × 10 ⁰ s ⁻¹ , and 580%, 370%, 340 respectively. %, High stretch ratio of 250%. In this way, a magnesium alloy in the vicinity of the eutectic point containing a large amount of phase can be stably hot-extruded and hot-rolled, the crystal grains are refined, and formability is excellent. It was confirmed that.

[Example 6]
This example relates to the production of extruded materials and plates of Mg-Ce-based Misch metal alloys in the hypo-eutectic region.

  The mixture was mixed with Mg (95.7 at%)-Ce-based Misch metal (4.3 at%) at an atomic weight percentage, cast under the same conditions as in Example 5, and subjected to hot extrusion and hot rolling. FIG. 7 is a structure photograph in which the specimen is hot-pressed under the above-mentioned conditions, and without any cracks, the average crystal grain size is 15 μm and is fine. Also, FIG. 8 is a structure photograph obtained by hot rolling the above-described hot-pressed magnesium alloy processed material, without any cracks in the structure, and the average crystal grain size is 8 μm and very fine crystal grains are generated. It was.

  In this example, in the case of a magnesium alloy containing a large amount of phase up to the hypo-eutectic region, the crystal grains are refined by stable hot extrusion and hot rolling. It was confirmed.

[Example 7]
This example is for the production of Mg-Ce-based Misch metal-Zn alloy extrusions and plates in the hypo-eutectic region.

  At a weight percentage of%, mix with Mg (97.0 at%)-Ce-based Misch metal (1.5 at%)-Zn (1.5 at%), cast under the same conditions as in Example 5, and hot extrude And hot rolling. FIG. 9 is a structural photograph in which this specimen was hot-pressed under the above conditions, and the average crystal grain size was 20 μm without any cracks inside. FIG. 10 shows a microstructure photograph of the hot-rolled magnesium alloy processed material hot-rolled, and the average crystal grain size is 9 μm and is fine. In this example, in the case of a magnesium alloy containing a large amount of phase up to the hypo-eutectic region, it was confirmed that the crystal grains can be refined with stable hot extrusion. .

  As described above, according to the magnesium alloy to which the misch metal of the present invention is added, the misch metal is added and the second phase or multi-phases are solid network structure or dispersion. By forming a phase, the deformation of the magnesium substrate is suppressed at high temperatures, and further elements are added to enhance precipitation / solid solution in the substrate structure, or the neckwork structure is strengthened to increase the temperature. Excellent mechanical properties to maintain high strength.

  Further, according to the method for producing a processed magnesium alloy material of the present invention, the second-phase or multi-phase magnesium alloy to which misch metal is added is recrystallized through hot extrusion and hot rolling processes. As a result, the crystal grains become finer.

  In addition, the processed magnesium alloy material to which the misch metal of the present invention is added has a fine crystal structure, and exhibits mechanical properties having high strength and high toughness in a normal temperature region where the alloy is actually used. The stretch ratio is excellent at the temperature at which it is molded, and the moldability is improved.

  Thus, the magnesium alloy to which the misch metal of the present invention having excellent mechanical properties is added satisfies the high strength and heat resistance requirements required for power transmission parts of automobiles and the like.

  Further, by adding calcium (Ca) to the magnesium alloy to which the misch metal of the present invention is added, melting and casting can be performed in the atmosphere, and production cost can be reduced.

  In addition, the magnesium alloy to which the misch metal of the present invention is added exhibits a high temperature strength superior to that of the heat-resistant magnesium alloy produced through the existing heat treatment, and thus can be applied to automobile and aircraft parts.

  In addition, the magnesium alloy to which the misch metal according to the present invention is added exhibits a relatively superior corrosion resistance and superior performance compared to existing commercial heat-resistant magnesium alloys, so that it can withstand the severe conditions of high temperature and corrosion. Used for parts.

  In addition, according to the method for manufacturing a processed magnesium alloy material to which the misch metal is added according to the present invention, it is possible to produce a magnesium alloy plate material containing a large amount of ultrafine particles, and the manufactured magnesium plate material is crystallized. The grains are fine and the formability is very good. Therefore, the magnesium alloy processed material of the present invention can be widely applied as an exterior material for mobile communication and electronic / communication products such as a notebook computer so that roads, aviation, and railway transportation means can be reduced in weight. it can.

FIG. 1 is a scanning electron microscope (SEM) photograph showing Alloy 3 in Table 1 and an alpha magnesium structure and a network structure of Mg ₁₂ Ce phase. FIG. 2 is a photograph of molten metal in which 2 wt% calcium (Ca) is added to Alloy 9 in Table 1 and dissolved in the atmosphere. FIG. 3 is a photograph of the cast structure near the eutectic point according to Example 5. FIG. 4 is a structural photograph of a workpiece obtained by hot extruding the alloy according to Example 5 at a temperature of 450 ° C., an extruding speed of 2 mm / sec, and an extruding ratio of 6: 1. FIG. 5 is a microstructure photograph of a processed material obtained by rolling the alloy according to Example 5 from a specimen temperature of 400 ° C. and a roll temperature of 100 ° C. at a thickness reduction rate of 40%. FIG. 6 shows the deformation ratio of ¹ × 10 ⁻³ s ⁻¹ , ¹ × 10 ⁻² s ⁻¹ , ¹ × 10 ⁻¹ s ⁻¹ at a temperature of 500 ° C. It is the test piece photograph and stretching ratio of the tensile test result conducted at ¹ × 10 ⁰ s ⁻¹ . FIG. 7 is a structural photograph of a workpiece obtained by hot-pressing the alloy of Example 6 at a specimen temperature of 450 ° C., a pressing speed of 2 mm / second, and a pressing ratio of 6: 1. FIG. 8 is a microstructure photograph of a processed material obtained by rolling the hot-pressed alloy of Example 6 from a specimen temperature of 400 ° C. and a roll temperature of 100 ° C. at a thickness reduction rate of 40%. FIG. 9 is a structural photograph of a processed material obtained by hot extruding the alloy of Example 7 at a specimen temperature of 450 ° C., an extruding speed of 2 mm / sec, and an extruding ratio of 6: 1. FIG. 10 is a microstructure photograph of a processed material obtained by rolling the hot-pressed alloy of Example 7 from a specimen temperature of 400 ° C. and a roll temperature of 100 ° C. at a thickness reduction rate of 40%.

Claims (12)

Expressed by the general formula Mg _100-xyz A _x B _y C _z
The A represents zinc (Zn) or aluminum (Al) element, the B is misch metal, the element C is silicon (Si), boron (B), manganese (Mn), nickel (Ni), copper (Cu) , Tin (Sn), yttrium (Y), phosphorus (P), silver (Ag), or strontium (Sr), wherein x, y and z are each 0 at A magnesium alloy to which a misch metal is added, characterized in that% ≦ x ≦ 6 at%, 0.8 at% ≦ y ≦ 7 at%, and 0 at% ≦ z ≦ 2 at%.   2. The magnesium alloy to which misch metal is added according to claim 1, further comprising 2 at% or less of calcium.   The magnesium alloy according to claim 1, wherein the misch metal is a didymium misch metal or a cerium misch metal.   The magnesium alloy to which the misch metal is added according to claim 3, wherein the didymium misch metal has a rare earth alloy composition including Nd (neodymium) and Pr (praseodymuim).   The cerium (Ce) based misch metal includes 45 wt% ≤ Ce ≤ 65 wt%, 20 wt% ≤ La ≤ 30 wt%, 5 wt% ≤ Nd ≤ 15 wt%, 0 wt% ≤ Pr ≤ 10 wt%. 3. A magnesium alloy to which the misch metal described in 3 is added. Expressed by the general formula Mg _100-xyz A _x B _y C _z , the A represents a zinc (Zn) or aluminum (Al) element, the B represents a misch metal, the element C represents silicon (Si), boron ( B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P), silver (Ag), one selected from strontium (Sr) Alternatively, two or more elements, wherein x, y, and z are melt casted with a magnesium alloy composition in which 0 at% ≦ x ≦ 6 at%, 0.8 at% ≦ y ≦ 7 at%, and 0 at% ≦ z ≦ 2 at%, respectively. And the stage of
A step of hot-pressing the cast material to granulate and disperse phases other than magnesium in the cast material, and refining the crystal grains through recrystallization of the substrate. Magnesium alloy processed material manufacturing method.   The method of manufacturing a magnesium alloy processed material to which misch metal is added according to claim 6, further comprising a step of hot rolling the hot extruded material to form a plate material.   The magnesium added with misch metal according to claim 6, wherein the hot pressing step is performed under a pressing condition of a temperature range of 350 to 450 ° C and a cross-sectional reduction ratio of 5 to 80: 1. Alloy processed material manufacturing method.   The magnesium alloy processing with added misch metal according to claim 7, wherein the hot rolling step is performed in a temperature range of 350 to 500 ° C. and a rolling condition of a rolling reduction rate of 25-50%. Material manufacturing method. Expressed by the general formula Mg _100-xyz A _x B _y C _z , the A represents a zinc (Zn) or aluminum (Al) element, the B represents a misch metal, the element C represents silicon (Si), boron ( B), manganese (Mn), nickel (Ni), copper (Cu), tin (Sn), yttrium (Y), phosphorus (P), silver (Ag), one selected from strontium (Sr) Alternatively, two or more elements, wherein x, y, and z are respectively 0 at% ≦ x ≦ 6 at%, 0.8 at% ≦ y ≦ 7 at%, and 0 at% ≦ z ≦ 2 at% are melt cast. When,
A step of hot-pressing the cast material to refine crystal grains through particle formation of a phase other than magnesium in the cast material, dispersion, and recrystallization of the substrate;
A magnesium alloy processed material to which misch metal is added, wherein the processed material is manufactured by hot rolling the hot extruded material.   11. The magnesium alloy processed material to which misch metal is added according to claim 10, wherein the phase size other than magnesium is 20 μm or less.   11. The magnesium alloy processed material to which misch metal is added according to claim 10, wherein elements other than magnesium are included from a solid solution limit to a eutectic point or a hypereutectic region.

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