|
(11) | EP 2 298 944 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||
| (54) | Magnesium master alloy, manufacturing method thereof, metal alloy using the same, and method of manufacturing the metal alloy |
| (57) Provided are a magnesium mother alloy, a manufacturing method thereof, a metal alloy
using the same, and a method of manufacturing the metal alloy. In particular, there
are provided a magnesium mother alloy with improved oxidation and ignition properties,
and a manufacturing method thereof, and also provided a metal alloy with low cost
that is suitable for design purposes using the magnesium mother alloy, and a method
of manufacturing the metal alloy. The magnesium mother alloy includes a plurality
of magnesium grains, and scandium dissolved in the magnesium grains, or a scandium
compound crystallized at grain boundaries which are not inside but outside the magnesium
grains. Also, the metal alloy suitable for design purposes is manufactured at low
cost by adding the magnesium mother alloy containing scandium into a magnesium alloy
or an aluminum alloy.
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0088959, filed on September 21, 2009, the entire content of which is incorporated herein by reference.
BACKGROUND
1. Field
[0002] Example embodiments relate to a magnesium mother alloy, a manufacturing method thereof, a metal alloy using the same, and a method of manufacturing the metal alloy.
2. Description of the Related Art
[0003] Technologies of using scandium (Sc) as an additive in super-hard aluminum alloys (for example, 2000-series, 5000-series, 6000-series, 7000-series aluminum alloys, etc.) have recently been studied so as to improve alloy properties such as hardness, corrosion resistance and weldability. Aluminum alloys with Sc added may be used for military purposes (for example, reinforcement for combat vehicles, rifle bodies, etc.) requiring good weldability and fatigue resistance, or may be used for private purposes (for example, a high-speed train, parts for an electric train, etc.).
[0004] However, Sc is a rare earth material, and the amount of Sc existing on the earth is too small. Furthermore, there is a difficulty in separating Sc from a mineral, and thus Sc is very expensive.
[0005] Therefore, a method of adding scandium oxide (Sc2O3) into aluminum alloys is now being considered because Sc2O3 is relatively cheaper than Sc itself.
[0006] When, however, Sc2O3 is directly added into aluminum alloys, various alloy properties such as hardness, corrosion resistance and weldability are deteriorated due to oxides of Sc.
SUMMARY
[0007] Embodiments are directed to a magnesium mother alloy, a manufacturing method thereof, a metal alloy using the same, and a method of manufacturing the metal alloy, which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art.
[0008] It is therefore a feature of an embodiment to provide a magnesium mother alloy with improved oxidation and ignition properties, and a manufacturing method thereof.
[0009] It is therefore a feature of another embodiment to provide a metal alloy with low cost, which is adapted for design purposes and does not deteriorate alloy properties such as hardness, corrosion resistance and weldability, and a manufacturing method thereof.
[0010] At least one of the above and other features and advantages may be realized by providing a magnesium mother alloy including: a plurality of magnesium grains; and scandium (Sc) dissolved in the magnesium grains.
[0011] The scandium may exist in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of magnesium.
[0012] At least one of the above and other features and advantages may be realized by providing a magnesium mother alloy including: a plurality of magnesium-aluminum grains having grain boundaries; and a scandium compound crystallized at the grain boundaries which are not inside but outside the magnesium-aluminum grains.
[0014] The scandium of the scandium compound may exist in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of the magnesium-aluminum
[0015] At least one of the above and other features and advantages may be realized by providing a method of manufacturing a magnesium mother alloy including: forming a magnesium melt by putting magnesium into a crucible and melting the magnesium at a temperature ranging from about 600 to about 800 °C; adding scandium oxide (Sc2O3) into the magnesium melt; stirring the magnesium melt for about 1 to about 400 minutes; pouring the magnesium melt into a mold having a temperature ranging from a room temperature to about 400 °C and casting the magnesium melt; and cooling the cast magnesium.
[0016] In the forming of the magnesium melt, the magnesium may be pure magnesium or magnesium-aluminum.
[0017] An added amount of the scandium oxide may be about 0.0001 to about 30 parts by weight based on 100 parts by weight of pure magnesium or magnesium-aluminum
[0018] At least one of the above and other features and advantages may be realized by providing a metal alloy including: a plurality of metal grains having grain boundaries; and scandium dissolved in the metal grains, or a scandium compound crystallized at the grain boundaries which are not inside but outside the metal grains.
[0019] The metal may include one selected from consisting of AZ91 D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MR1153, MR1230, AM-HP2, Mg-Al, Mg-AI-Re, Mg-AI-Sn, Mg-Zn-Sn, Mg-Si, and Mg-Zn-Y.
[0020] The metal may include one selected from consisting of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series, 6000-series, 7000-series and 8000-series wrought aluminum, and 100-series, 200-series, 300-series, 400-series, 500-series, and 700-series casting aluminum.
[0022] The scandium dissolved in the metal grains or the scandium of the scandium compound may exist in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of the metal.
[0023] At least one of the above and other features and advantages may be realized by providing a method of manufacturing a metal alloy including: forming a metal melt; adding a magnesium mother alloy containing dissolved scandium or scandium oxide (Sc2O3) into the metal melt; stirring the metal melt for about 1 to about 400 minutes; pouring the metal melt into a mold having a temperature ranging from a room temperature to about 400 °C and casting the metal melt; and cooling the cast metal.
[0024] An added amount of the magnesium mother alloy containing scandium may be about 0.0001 to about 30 parts by weight based on 100 parts by weight of metal.
[0025] The magnesium mother alloy containing scandium may be manufactured by adding about 0.0001 to about 30 parts by weight of scandium oxide (Sc2O3) based on 100 parts by weight of pure magnesium.
[0026] The magnesium mother alloy containing scandium may be manufactured by adding about 0.0001 to about 30 parts by weight of scandium oxide (Sc2O3) based on 100 parts by weight of magnesium-aluminum.
[0027] The magnesium mother alloy containing scandium may include an alloy prepared by adding about 0.0001 to about 30 parts by weight of scandium oxide (Sc2O3) based on 100 parts by weight of pure magnesium, and an alloy prepared by adding about 0.0001 to about 30 parts by weight of scandium oxide (Sc2O3) based on 100 parts by weight of magnesium-aluminum.
[0028] The metal melt may be formed of one selected from consisting of AZ91D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21 X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MR1153, MR1230, AM-HP2, Mg-Al, Mg-Al-Re, Mg-Al-Sn, Mg-Zn-Sn, Mg-Si, and Mg-Zn-Y
[0029] The metal melt may be formed of one selected from consisting of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series, 6000-series, 7000-series and 8000-series wrought aluminum, and 100-series, 200-series, 300-series, 400-series, 500-series, and 700-series casting aluminum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above and other features and advantages will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which:
[0031] FIG. 1 is a flowchart illustrating a method of manufacturing a magnesium mother alloy according to an embodiment;
[0032] FIG. 2 is a micrograph illustrating a microstructure of a magnesium mother alloy in which scandium oxide is added into pure magnesium and Sc exists in a solid-solution state;
[0033] FIG. 3 is a micrograph illustrating a microstructure of a magnesium mother alloy in which scandium oxide is added to magnesium-aluminum and a scandium compound is crystallized;
[0034] FIG. 4 is a graph illustrating hardness comparison results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment;
[0035] FIG. 5 is a graph illustrating oxidation experimental results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment;
[0036] FIG. 6 is a graph illustrating ignition experimental results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment;
[0037] FIG. 7 is a graph illustrating hardness comparison results between a magnesium-aluminum alloy and a magnesium-aluminum alloy with scandium oxide added according to an embodiment; and
[0038] FIG. 8 is a flowchart illustrating a method of manufacturing a metal alloy according to an embodiment.
DETAILED DESCRIPTION
[0039] Korean Patent Application No. 10-2009-0088959, filed on September 21, 2009, in the Korean Intellectual Property Office, and entitled: "Magnesium mother alloy, manufacturing method thereof, Metal alloy using the same, and Metal alloy manufacturing method thereof," is incorporated by reference herein in its entirety.
[0040] Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
[0041] FIG. 1 is a flowchart illustrating a method of manufacturing a magnesium mother alloy according to an embodiment.
[0042] The method of manufacturing the magnesium mother alloy includes forming a magnesium melt (S1), adding an additive (S2), stirring (S3), casting (S4), and cooling (S5).
[0043] In operation S1 of forming a magnesium melt, magnesium is put into a crucible and heated at a temperature ranging from about 600 °C to about 800 °C. Then, the magnesium in the crucible is molten to form a magnesium melt. Here, there is a difficulty in forming the magnesium melt when the temperature is less than 600 °C, whereas there is a danger that the magnesium melt is ignited when the temperature exceeds 800 °C.
[0044] Also, a small amount of a shield gas may be additionally provided to prevent the ignition of the magnesium melt. The shield gas may inhibit the ignition of the magnesium using SF6, SO2, CO2, HFC-134a, Novec™612, inert gas or an equivalent thereof, or a mixture gas thereof. However, in the embodiment, the shield gas may not necessarily used, and thus it may not be provided.
[0045] The magnesium used in operation S1 of forming the magnesium melt may be one selected from consisting of pure magnesium, magnesium-aluminum, and equivalents thereof.
[0047] Here, the additive used in operation S2 of adding the additive may not be pure Sc of high price, but may be one selected from consisting of scandium oxide (Sc2O3) which is relatively cheap, and equivalents thereof. The additive reduces the oxidation of a magnesium mother alloy, raises the ignition temperature, and remarkably reduces the required amount of the shield gas.
[0048] The additive used in operation S2 may be added in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of the magnesium mother alloy. When the amount of the additive is less than 0.0001 parts by weight, the effect (increase in hardness, decrease in oxidation, increase in ignition temperature and decrease in shield gas) resulting from the addition of the additive may be little. Also, when the amount of the additive exceeds 30 parts by weight, original magnesium properties or magnesium alloy properties may not appear.
[0049] The additive used in operation S2 may have a size ranging from about 0.1 µm to about 500 µm. It is difficult to manufacture an additive having a size of 0.1 µm or smaller actually, which requires high manufacturing cost. When the size of the additive exceeds about 500 µm, the additive may not react with the magnesium melt.
[0051] When the stirring time is less than 1 minute, the additive is not sufficiently mixed with the magnesium melt. In contrast, when the stirring time is greater than 400 minutes, the stirring time of the magnesium melt is unnecessarily lengthened.
[0052] Here, the additive added into the magnesium melt does not exist in an oxide form. For example, when scandium oxide (Sc2O3) is added into the magnesium melt, it does not exist in the form of Sc2O3. That is, Sc2O3, after being reduced, reacts with elements in the magnesium melt so that Sc is dissolved in grains to exist in an alloy form, or crystallized to exist in a compound form.
[0053] Typically, it is expected that Sc2O3 is not reduced in the magnesium melt because Sc2O3 is thermodynamically more stable than magnesium. However, according to experiments conducted by the present inventors, it was found out that Sc2O3 is reduced in the magnesium melt. This reduction mechanism is not revealed yet, and therefore the present inventors continue to study in order to diagnose the reduction mechanism.
[0054] Substantially, when Sc2O3 is added into pure magnesium, Sc is dissolved in the pure magnesium. That is, Sc forms an alloy element with magnesium. In addition, when Sc2O3 is added into magnesium-aluminum, a Sc compound is crystallized at a grain boundary of the magnesium-aluminum. That is, Sc does not form an alloy element with magnesium but forms the Sc compound. Here, the Sc compound is in the form of Al2Sc, AlSc or Al3Sc typically.
[0055] Of course, the other elements (O2) of the additives all float on the surface of the magnesium melt, and may be removed by manual or automatic equipment.
[0056] In casting operation S4, the magnesium melt is poured into a mold having a room temperature (e.g., about 25 °C) to about 400 °C, and then cast.
[0057] Here, the mold may be one selected from consisting of a metal type, a ceramic type, a graphite type and equivalents thereof. Also, a casting may be performed using gravity casting method, continuous casting method and equivalents thereof. However, the mold type and the casting method are not limited to the above.
[0058] In cooling operation S5, the mold is cooled down to a room temperature, and magnesium or magnesium-aluminum (e.g., ingot) is picked out of the mold.
[0059] Here, the magnesium mother alloy prepared through the above-described method, although will be explained below, may include a plurality of magnesium grains having grain boundaries therebetween, and Sc dissolved in the magnesium grains, or may include a scandium compound existing at the grain boundaries which are not inside but outside the magnesium grains.
[0060] FIG. 2 is a micrograph illustrating a microstructure of a magnesium mother alloy in which scandium oxide is added into pure magnesium and Sc exists in a solid-solution state. The microstructure shown in FIG. 2 is obtained by, for example, adding 0.5% scandium oxide into pure magnesium.
[0061] As shown in FIG. 2, a magnesium mother alloy 100 prepared according to an embodiment includes a plurality of magnesium grains 110, and scandium dissolved in the magnesium grains 110. Here, the scandium is not discriminated from the magnesium grains 110 substantially because scandium forms an alloy with magnesium.
[0062] Consequently, the hardness of the magnesium mother alloy manufactured by adding scandium oxide is improved compared to that of pure magnesium. In addition, since the scandium does not change the original composition of the magnesium mother alloy and does not disappear during a process of recycling the magnesium mother alloy, the reusability of magnesium mother alloy is considerably enhanced. That is, it is unnecessary to add scandium or scandium oxide again during the recycle of magnesium mother alloy.
[0063] Also, about 0.0001 to about 30 parts by weight of scandium oxide may be added based on 100 parts by weight of magnesium. The scandium oxide may have a size ranging from about 0.1 µm to about 500 µm. The meaning of such a numerical range has already been described above.
[0064] FIG. 3 is a micrograph illustrating a microstructure of a magnesium mother alloy in which scandium oxide is added to magnesium-aluminum and a scandium compound is crystallized. For example, the microstructure in FIG. 3 is obtained by adding 0.5% scandium oxide into magnesium-aluminum (Mg-3Al).
[0065] As shown in FIG. 3, a magnesium mother alloy 200 according to an embodiment includes a plurality of magnesium-aluminum grains 210, and a scandium compound 211.
[0066] The plurality of magnesium-aluminum grains 210 have grain boundaries therebetween, and the scandium compound 211 exist at the grain boundaries which are not inside the grains 210 but outside the magnesium-aluminum grains 210. Here, the scandium compound 211 exists in the form of Al2Sc, AlSc or Al3Sc. That is, the scandium does not form an alloy with magnesium.
[0067] As such, the hardness of the magnesium mother alloy 200 is enhanced, which will be described below. Since the scandium does not change the original composition of the magnesium mother alloy and does not disappear during a process of recycling the magnesium mother alloy, the reusability of magnesium mother alloy is considerably enhanced. For example, it is unnecessary to add scandium or scandium oxide again during the recycle of magnesium mother alloy.
[0068] Also, about 0.0001 to about 30 parts by weight of the scandium compound 211 may be added based on 100 parts by weight of magnesium-aluminum. The scandium compound 211 may have a size ranging from about 0.1 µm to about 500 µm. The meaning of such a numerical range has been already described above.
[0069] The magnesium mother alloy may be used as one selected from consisting of an incombustible alloy, a wrought alloy, a creep alloy, a damping alloy, a degradable bio ally, and a powder metallurgy.
[0070] For example, the casting alloy may be formed by mixing AZ91 D, AM20, AM50, or AM60 with scandium oxide.
[0072] The creep alloy may be formed by mixing Mg-Al, or Mg-Al-Re with scandium oxide. Furthermore, the creep alloy may be formed by mixing Mg-Al-Sn or Mg-Zn-Sn with scandium oxide.
[0076] Of course, in all the alloys, only scandium, which is obtained by removing O2 from scandium oxide, is crystallized and present at grain boundaries, or the scandium exists in the grains in a solid-solution state finally.
[0077] FIG. 4 is a graph illustrating hardness comparison results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment. In FIG. 4, the X-axis represents a pure magnesium and a magnesium into which 0.5% scandium oxide is added, and the Y-axis represents hardness (HR).
[0078] As shown in FIG. 4, it can be observed that the hardness increases when scandium oxide is added during the manufacture of a magnesium mother alloy. That is, the hardness of the pure magnesium without scandium oxide is about HRF41, whereas the hardness of the magnesium mother alloy with scandium oxide added increases up to about HRF53.
[0079] FIG. 5 is a graph illustrating oxidation experimental results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment. In FIG. 5, the X-axis represents an elapse time (min.), and the Y-axis represents oxidation amount (%). A reference value of the Y-axis is set to 100.
[0080] As shown in FIG. 5, in the pure magnesium, it can be observed that the oxidation of the pure magnesium is accelerated with the lapse of time, and thus the value of the Y-axis increases gradually. However, in the magnesium mother alloy into which scandium oxide is added during manufacturing process, it can be observed that the oxidation does not increase even after the lapse of time. That is, the magnesium mother alloy according to an embodiment is stable for various applications because it is not oxidized even after the lapse of time.
[0081] FIG. 6 is a graph illustrating ignition experimental results between a pure magnesium and a magnesium mother alloy with scandium oxide added according to an embodiment. In FIG. 6, the X-axis represents a pure magnesium and a magnesium into which 0.5% scandium oxide is added, and the Y-axis represents an ignition temperature (°C).
[0082] As illustrated in FIG. 6, it can be observed that the ignition temperature of the magnesium mother alloy with scandium oxide added is increased. That is, the ignition temperature of the pure magnesium without scandium oxide is about 600 °C, whereas the ignition temperature of the magnesium mother alloy with scandium oxide added increases up to about 700 °C.
[0083] FIG. 7 is a graph illustrating hardness comparison results between a magnesium-aluminum alloy and a magnesium-aluminum alloy with scandium oxide added according to an example embodiment. In FIG. 7, the X-axis represents a magnesium-aluminum alloy and a magnesium-aluminum alloy into which 0.5% scandium oxide is added, and the Y-axis represents hardness (HR).
[0084] As shown in FIG. 7, it can be observed that the hardness increases when scandium oxide is added during the manufacture of a magnesium-aluminum alloy. That is, the hardness of the magnesium-aluminum alloy without scandium oxide is about HRF50, whereas the hardness of the magnesium-aluminum alloy with scandium oxide added increases up to HRF68.
[0085] FIG. 8 is a flowchart illustrating a method of manufacturing a metal alloy according to an embodiment.
[0086] The method of manufacturing the metal alloy includes forming a metal melt (S11), adding a magnesium mother alloy containing scandium (S12), stirring (S13), casting (S14), and cooling (S15).
[0087] In operation S11 of forming a metal melt, a magnesium alloy or an aluminum alloy is put into a crucible and heated at a temperature ranging from about 600 °C to about 800 °C. Then, the metal in the crucible is molten to form a metal melt. Here, there is a difficulty in forming the metal melt when the temperature is less than 600 °C, whereas there is a danger that the metal melt is ignited when the temperature exceeds 800 °C.
[0088] Here, the metal may be a magnesium alloy selected from consisting of AZ91D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21 X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MR1153, MR1230, AM-HP2, Mg-Al, Mg-Al-Re, Mg-Al-Sn, Mg-Zn-Sn, Mg-Si, and Mg-Zn-Y.
[0089] Also, the metal may be a metal alloy selected from consisting of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series, 6000-series, 7000-series and 8000-series wrought aluminum, and 100-series, 200-series, 300-series, 400-series, 500-series, and 700-series casting aluminum.
[0090] Herebelow, the aluminum alloys will be more specifically described. Various kinds of aluminum alloys have been developed for their use, and most of countries currently classify the kinds of aluminum alloys according to the standard stipulated by the Aluminum Association of America. Main alloy elements for each of alloy series are listed in Table 1 below in which a serial number is only shown in units of thousand. In case of improving each of the alloy series by adding other elements, an alloy name is designated by subdividing four digits number more specifically.
[0091]
[Table 1] Classification of aluminum according to alloy series
| Alloy Series | Main alloy elements |
| 1000-series Al | Pure Al |
| 2000-series Al | Al-Cu-(Mg)-based Al alloy |
| 3000-series Al | Al-Mn-based Al alloy |
| 4000-series Al | Al-Si-based Al alloy |
| 5000-series Al | Al-Mg-based Al alloy |
| 6000-series Al | Al-Mg-Si-based Al alloy |
| 7000-series Al | Al-Zn-Mg-(Cu)-based Al alloy |
| 8000-series Al | Others |
[0092] The first number denotes an alloy series representing main alloy elements, and the second number denotes whether a basic alloy is improved or not. That is, the second number of 0 represents a basic alloy, and the second number of 1 to 9 represents alloys improved from the basic alloy. Further, when a new alloy is developed, the second number is indicated by a capital letter N. For example, 2xxx represents a basic alloy of Al-Cu series aluminum, 21xx∼29xx represents alloys obtained by improving an Al-Cu basic alloy, and 2Nxx represents a newly developed alloy which is not stipulated in the standard of the Aluminum Association of America. The third and fourth numbers represent the purity of a pure aluminum or an alloy name of an aluminum alloy that Alcoa Inc. has used in the past. For example, in case of pure aluminum, 1080 indicates that the content of aluminum is 99.80% or higher, and 1100 indicates that the content of aluminum is 99.00% or higher.
[0093] Main compositions of wrought alloys are listed in Table 2 below. Properties of each alloy may significantly differ according to composition metals and their amounts, and working process.
[0095]
[Table 2] Main composition of aluminum alloy
| Grade | Added metal(element symbol), Unit: % | Use | ||||||
| Si | Cu | Mn | Mg | Cr | Zn | others | ||
| 1100 | 0.12 | Si 1%, Abundant Metal | foils, cooking utensils | |||||
| 1350 | About others | 0.5% Conductive material | ||||||
| 2008 | 0.7 | 0.9 | 0.4 | Metal plates for vehicles | ||||
| 2014 | 0.8 | 4.4 | 0.8 | 0.5 | Exterior of aircraft, truck frame | |||
| 2024 | 4.4 | 0.6 | 1.5 | Exterior of aircraft, truck wheel | ||||
| 2036 | 2.6 | 0.25 | 0.45 | Metal plates for vehicles | ||||
| 2090 | 2.7 | Li 2.2, Zr 0.12 | Metal for aircraft | |||||
| 2091 | 2.2 | 1.5 | Li 2.0, Zr 0.12 | Metal for aircraft | ||||
| 2219 | 6.3 | 0.3 | V 0.1, Zr 0.18, Ti 0.06 | Metal for spacecraft, weldable | ||||
| 2519 | 5.9 | 0.3 | 0.2 | V 0.1, Zr 0.18 | Military equipment, metal for spacecraft, weldable | |||
| 3003 | 0.12 | 1.1 | General use, cooking utensils | |||||
| 3004 | 1.1 | 1.0 | General use, metal can | |||||
| 3105 | 0.6 | 0.5 | Building materials | |||||
| 5052 | 2.5 | 0.25 | General use | |||||
| 5083 | 0.7 | 4.4 | 0.15 | Heat-/Pressure-resistant vessels | ||||
| 5182 | 0.35 | 4.5 | Metal can, metal for vehicles | |||||
| 5252 | 2.5 | For vehicle bodies | ||||||
| 6009 | 0.8 | 0.33 | 0.33 | 0.5 | Metal plates for vehicles | |||
| 6010 | 1.0 | 0.33 | 0.33 | 0.8 | Metal plates for vehicles | |||
| 6013 | 0.8 | 0.8 | 0.5 | 1.0 | Metal for spacecraft | |||
| 6061 | 0.6 | 0.25 | 1.0 | 0.20 | General use | |||
| 6063 | 0.4 | 0.7 | General use, injection molding | |||||
| 6201 | 0.7 | 0.8 | Conductive material | |||||
| 7005 | 0.45 | 1.4 | 0.13 | 4.5 | Zr 0.14 | Truck body, train | ||
| 7075 | 1.6 | 2.5 | 0.25 | 5.6 | Metal for aircraft | |||
| 7150 | 2.2 | 2.3 | 6.4 | Zr 0.12 | Metal for spacecraft | |||
| 8090 | 1.3 | 0.9 | Li 2.4, Zr 0.12 | Metal for spacecraft | ||||
[0096] In operation S12 of adding the magnesium mother alloy, a magnesium mother alloy containing Sc is added to the metal melt. Here, as described above, the metal melt may be a magnesium alloy or an aluminum alloy.
[0097] The magnesium mother alloy used in operation S12 may be manufactured by adding one selected from consisting of scandium oxide (Sc2O3), which is cheaper than pure Sc, and equivalents thereof, into magnesium or magnesium-aluminum. The magnesium and magnesium-aluminum, and methods thereof have been fully described above, and thus further description will be omitted herein.
[0098] In this way, according to an exemplary embodiment, magnesium or magnesium-aluminum alloy containing scandium that is prepared at low cost is added into a metal melt, thus making it possible to solve several problems occurring when scandium oxide is directly put into the metal melt. For example, the direct addition of scandium oxide (Sc2O3) into aluminum causes the quality of an alloy to be deteriorated due to oxides, however, the quality of an alloy is not deteriorated by adding magnesium or magnesium-aluminum alloy containing scandium according to the embodiment. More specifically, alloy properties such as hardness, corrosion resistance and weldability are deteriorated when scandium oxide (Sc2O3) is directly added into aluminum, however, alloy properties such as hardness, corrosion resistance and weldability in the metal alloy according to the embodiment are maintained without a change when magnesium or magnesium-aluminum already containing scandium is added into aluminum.
[0099] For instance, 5000-series metal alloys are strong, easy to be molded, and highly resistant to corrosion, in comparison with 3000-series metal alloys. Furthermore, 5000-series metal alloys are weldable. In particular, the 5182 alloy may be used for a cover of an aluminum can. In addition, 5005 and 5083 alloys, and 5052, 5056, 5086 and varieties thereof may widely be used for electric facilities, various cooking utensils, metal plate, pressure-resistant vessels, transmission towers of radio wave, welding structures, boats, reservoirs for chemicals, etc. Insect nets, nails, and fasteners may be made of 5000-series alloys. When magnesium or magnesium-aluminum alloy already containing scandium is added into such 5000-series metal alloys having the above properties, it is possible to obtain an aluminum alloy with good hardness, corrosion resistance and weldability at low cost.
[0100] The additive used in operation S12 of adding the magnesium mother alloy may be added in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of the metal. When the amount of the additive is less than 0.0001 parts by weight, the effect (hardness, corrosion resistance, and weldability) resulting from the addition of magnesium may be little. Also, when the amount of the additive exceeds 30 parts by weight, original metal properties may not appear.
[0101] Furthermore, the additive used in operation S12 of adding the magnesium mother alloy may have a size ranging from about 0.1 µm to about 500 µm. It is difficult to manufacture an additive having a size of 0.1 µm or smaller actually, leading to high manufacturing cost. When the size of the additive exceeds 500 µm, the magnesium may not react with the metal melt.
[0102] Likewise, the additive used in operation S12 of adding the magnesium-aluminum may be added in an amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of the metal alloy. When the amount of the additive is less than 0.0001 parts by weight, the effect (hardness, corrosion resistance, and weldability) resulting from the addition of magnesium may be little. Also, when the amount of the additive exceeds 30 parts by weight, original metal properties may not appear.
[0103] Furthermore, the additive used in operation S12 of adding the magnesium-aluminum may have a size ranging from about 0.1 µm to about 500 µm. It is difficult to manufacture an additive having a size of 0.1 µm or smaller actually, leading to high manufacturing cost. When the size of the additive exceeds 500 µm, the of adding the magnesium-aluminum may not react with the metal melt.
[0105] When the stirring time is less than 1 minute, the additive is not sufficiently mixed with the metal melt. In contrast, when the stirring time is greater than 400 minutes, the stirring time of the metal melt is unnecessarily lengthened.
[0106] Here, when the metal melt is an aluminum melt, scandium contained in the magnesium added into the aluminum melt exists in the form of Al2Sc, AlSc or Al3Sc due to the high affinity between Sc and Al.
[0107] In stirring operation S13, Al2Sc, AlSc or Al3Sc does not exist in metal grains, but exists outside the metal grains, i.e., at grain boundaries, in the form of an intermetallic compound. That is, the metallic compound of Al2Sc, AlSc or Al3Sc is formed in stirring operation S13.
[0108] In casting operation S14, the metal melt is poured into a mold at a room temperature (e.g., about 25 °C) to about 400 °C, and then cast.
[0109] Here, the mold may be one selected from consisting of a metal type, a ceramic type, a graphite type and equivalents thereof. Also, a casting may be performed using gravity casting method, continuous casting method and equivalents thereof. However, the mold type and the casting method are not limited to the above.
[0110] In cooling operation S15, the mold is cooled down to a room temperature, and a metal alloy (e.g., metal alloy ingot) is picked out of the mold.
[0111] Here, the metal alloy manufactured through the above-described method includes a plurality of metal grains having grain boundaries therebetween, and an intermetallic compound (i.e., Al2Sc, AlSc or Al3Sc) existing at the grain boundaries which are not inside but outside the metal grains. Of course, in case where the metal is pure magnesium, Sc is dissolved in the metal grains.
[0112] As such, according to an exemplary embodiment, a magnesium mother alloy (Sc-containing magnesium or Sc-containing magnesium-aluminum) is added into a metal melt (magnesium alloy or aluminum alloy), thus making it possible to solve several problems occurring when scandium oxide is directly put into the metal melt. For example, the direct addition of scandium oxide (Sc2O3) into aluminum causes the quality of an alloy to be deteriorated due to oxides, however, the addition of Sc-containing magnesium or Sc-containing magnesium-aluminum into aluminum according to an embodiment enables the aluminum alloy to be manufactured at low cost while not deteriorating the quality (hardness, corrosion resistance, weldability, etc.) of an alloy.
[0113] Table 3 below shows experimental data for strength of an aluminum alloy manufactured through the above-described method.
[0114]
[Table 3]
| Strength of 7000-series Al alloy | Including Sc | 650-700MPa |
| Not including Sc | 550-600MPa | |
| Strength of 5000-series Al alloy | Including Sc | 450-500MPa |
| Not including Sc | 350-400MPa |
[0115] As shown in Table 3, it can be understood that the strength increases up to about 650-700 MPa from about 550-600 MPa when magnesium or magnesium-aluminum, into which Sc has been already added, is added into 7000-series Al alloy through the above-described method.
[0116] It can be also understood from Table 3 that the strength increases up to about 450-500 MPa from about 350-400 MPa when magnesium or magnesium-aluminum, into which Sc has been already added, is added into 5000-series Al alloy through the above-described method.
[0117] As such, in a metal alloy and a method thereof according to the embodiments, a magnesium mother alloy containing Sc is added into a metal alloy such as a magnesium alloy or an aluminum alloy, and thus the metal alloy is manufactured at low cost. Furthermore, alloy properties of the metal alloy, e.g., hardness, corrosion resistance and weldability, are not deteriorated.
[0118] In addition, according to the embodiments, the magnesium mother alloy is manufactured in such a form that Sc is dissolved in metal grains, or Sc is crystallized at grain boundaries, which makes it possible to easily manufacture a metal alloy suitable for use or purpose. For example, when a metal alloy where Sc is dissolved is required, a magnesium mother alloy where Sc is dissolved in the metal grains may be used. Also, when a metal alloy where Sc is crystallized is required, a magnesium mother alloy where Sc is crystallized at the grain boundaries may be used. Of course, a metal alloy may be manufactured by adding both of the magnesium mother alloy where Sc is dissolved in metal grains and the magnesium mother alloy where Sc is crystallized at the grain boundaries.
[0119] As described above, according to foregoing embodiments, oxidation and ignition properties of a magnesium mother alloy are enhanced by adding scandium oxide into the magnesium mother alloy. Also, a metal alloy can be manufactured at low cost because the magnesium mother alloy containing scandium is added into a metal alloy such as a magnesium alloy and an aluminum alloy. In this case, alloy properties, e.g., hardness, corrosion resistance, and weldability, of the metal alloy are not deteriorated.
[0120] Moreover, it is possible to manufacture a metal alloy suitable for use and purpose by preparing two types of mother alloys of which one is a magnesium mother alloy containing scandium dissolved in grains, and the other is a magnesium mother alloy where scandium is crystallized. For example, when a metal alloy where Sc is dissolved is required, a magnesium mother alloy where Sc is dissolved in the metal grains may be used. Also, when a metal alloy where Sc is crystallized is required, a magnesium mother alloy where Sc is crystallized at the grain boundaries may be used. Of course, a metal alloy may be manufactured by adding both of the magnesium mother alloy where Sc is dissolved in metal grains and the magnesium mother alloy where Sc is crystallized at the grain boundaries. Accordingly, according to the embodiments, it is possible to manufacture metal alloys suitable for use and purpose through various methods.
[0121] A magnesium mother alloy, a manufacturing method thereof, a metal alloy using the same, and a method of manufacturing the metal alloy according to exemplary embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
1. A magnesium mother alloy, comprising:
a plurality of magnesium grains; and
scandium (Sc) dissolved in the magnesium grains.
2. The magnesium mother alloy as claimed in claim 1, wherein the scandium exists in an
amount of about 0.0001 to about 30 parts by weight based on 100 parts by weight of
magnesium.
3. A magnesium mother alloy, comprising:
a plurality of magnesium-aluminum grains having grain boundaries; and
a scandium compound crystallized at the grain boundaries which are not inside but outside the magnesium-aluminum grains.
4. The magnesium mother alloy as claimed in claim 3, wherein the scandium compound includes
Al2Sc, AlSc and Al3Sc.
5. The magnesium mother alloy as claimed in claim 3, wherein the scandium of the scandium
compound exists in an amount of about 0.0001 to about 30 parts by weight based on
100 parts by weight of the magnesium-aluminum.
6. A method of manufacturing a magnesium mother alloy, the method comprising:
forming a magnesium melt by putting magnesium into a crucible and melting the magnesium at a temperature ranging from about 600 to about 800 °C;
adding scandium oxide (Sc2O3) into the magnesium melt;
stirring the magnesium melt for about 1 to about 400 minutes;
pouring the magnesium melt into a mold having a temperature ranging from a room temperature to about 400 °C and casting the magnesium melt; and
cooling the cast magnesium.
7. The method as claimed in claim 6, wherein, in the forming of the magnesium melt, the
magnesium is pure magnesium or magnesium-aluminum.
8. The method as claimed in claim 6, wherein an added amount of the scandium oxide is
about 0.0001 to about 30 parts by weight based on 100 parts by weight of pure magnesium
or magnesium-aluminum.
9. A metal alloy, comprising:
a plurality of metal grains having grain boundaries; and
scandium dissolved in the metal grains, or a scandium compound crystallized at the grain boundaries which are not inside but outside the metal grains.
10. The metal alloy as claimed in claim 9, wherein the metal includes one selected from
consisting of AZ91 D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21X,
AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MR1153, MR1230, AM-HP2, Mg-Al, Mg-Al-Re,
Mg-Al-Sn, Mg-Zn-Sn, Mg-Si, and Mg-Zn-Y.
11. The metal alloy as claimed in claim 9, wherein the metal includes one selected from
consisting of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series, 6000-series,
7000-series and 8000-series wrought aluminum, and 100-series, 200-series, 300-series,
400-series, 500-series, and 700-series casting aluminum.
12. The metal alloy as claimed in claim 9, wherein the scandium compound includes Al2Sc, AlSc and Al3Sc.
13. The metal alloy as claimed in claim 9, wherein the scandium dissolved in the metal
grains or the scandium of the scandium compound exists in an amount of about 0.0001
to about 30 parts by weight based on 100 parts by weight of the metal.
14. A method of manufacturing a metal alloy, the method comprising:
forming a metal melt;
adding a magnesium mother alloy containing dissolved scandium or scandium oxide (Sc2O3) into the metal melt;
stirring the metal melt for about 1 to about 400 minutes;
pouring the metal melt into a mold having a temperature ranging from a room temperature to about 400 °C and casting the metal melt; and
cooling the cast metal.
15. The method as claimed in claim 14, wherein an added amount of the magnesium mother
alloy containing scandium is about 0.0001 to about 30 parts by weight based on 100
parts by weight of metal.
16. The method as claimed in claim 14, wherein the magnesium mother alloy containing scandium
is manufactured by adding about 0.0001 to about 30 parts by weight of scandium oxide
(Sc2O3) based on 100 parts by weight of pure magnesium.
17. The method as claimed in claim 14, wherein the magnesium mother alloy containing scandium
is manufactured by adding about 0.0001 to about 30 parts by weight of scandium oxide
(Sc2O3) based on 100 parts by weight of magnesium-aluminum.
18. The method as claimed in claim 14, wherein the magnesium mother alloy containing scandium
includes an alloy prepared by adding about 0.0001 to about 30 parts by weight of scandium
oxide (Sc2O3) based on 100 parts by weight of pure magnesium, and an alloy prepared by adding
about 0.0001 to about 30 parts by weight of scandium oxide (Sc2O3) based on 100 parts by weight of magnesium-aluminum.
19. The method as claimed in claim 14, wherein the metal melt is formed of one selected
from consisting of AZ91 D, AM20, AM30, AM50, AM60, AZ31, AZ61, AZ80, AS41, AS31, AS21X,
AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MR1153, MR1230, AM-HP2, Mg-Al, Mg-Al-Re,
Mg-Al-Sn, Mg-Zn-Sn, Mg-Si, and Mg-Zn-Y.
20. The method as claimed in claim 14, wherein the metal melt is formed of one selected
from consisting of 1000-series, 2000-series, 3000-series, 4000-series, 5000-series,
6000-series, 7000-series and 8000-series wrought aluminum, and 100-series, 200-series,
300-series, 400-series, 500-series, and 700-series casting aluminum.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description