JP7324978B2 - Magnesium alloys and cast structural members using magnesium alloys - Google Patents

Description

The present invention relates to magnesium alloys and cast structural members using magnesium alloys.

2. Description of the Related Art Various metal materials are used to construct housings and various parts in various equipment and devices such as electronic equipment, precision equipment, transportation equipment such as automobiles and aircraft, and manufacturing machinery. Housings and various parts of such various devices and apparatuses are not only made of single metal materials such as iron and aluminum, but are increasingly made of various alloy materials.

Electronic devices and precision devices require weight reduction from the viewpoint of workability and portability. It requires sufficient durability and strength while being lightweight. From this point of view, lightweight alloy materials have come to be used as materials for composing (members) such as housings and various parts of electronic equipment and precision equipment.

In particular, transportation equipment is required to be lighter in order to improve fuel efficiency and transportation performance. If the weight of transportation equipment is reduced, the running performance and flight performance of the transportation equipment will be improved. Furthermore, if the weight of transportation equipment is reduced, the fuel consumption performance will be improved. Of course, there are many other benefits that come with weight reduction.

Naturally, transport equipment also requires sufficient durability and strength. From this point of view, lightweight alloy materials have come to be used. Alternatively, there is an increasing need for lightweight alloy materials. Even with such alloy materials, there is a demand for alloy materials suitable for casting processes such as die casting.

This also applies to manufacturing machines and the like. Ease of work, ease of transportation, low fuel consumption, ecology, etc. are required for many devices and devices, and weight reduction is required as one of the standards for realizing these. In order to achieve this weight reduction, lightweight alloy materials are used. or have been developed.

On the other hand, high thermal conductivity is also required for these devices and devices.

Electronic equipment and precision equipment perform electrical processing using semiconductor elements and the like. This electrical processing generates heat inside electronic devices and precision devices. The heat generated by this heat generation is undesirable in terms of the operation, maintenance of performance, durability, etc. of electronic equipment and precision equipment. Therefore, it is necessary to quickly and appropriately release this heat to the outside.

Transportation equipment also generates heat during operation due to the inclusion of internal combustion engines and drive engines. Excessive heat build-up or build-up is undesirable in terms of operating functions and performance maintenance. Of course, too much heat can adversely affect the strength and durability of transportation equipment.

Similarly, equipment and devices such as manufacturing machines cannot prevent heat generation during their operation. There are concerns about the effects of this heat on functions and performance, as well as on durability.

For this reason, high thermal conductivity is required for alloy materials constituting members of these devices and devices. This is because if the heat conductivity is high, the heat generated inside can be easily conducted through the members and the housing and released to the outside. Heat continues to be generated as long as the equipment or device is in operation. At this time, if the housing and members are made of a material with high thermal conductivity, the heat is efficiently conducted and continues to be released to the outside. This continuation can prevent deterioration in the performance of equipment and devices.

As described above, light weight is required for structural members (including members, parts, members, etc. used for structures) that constitute devices and housings of various devices including transportation equipment. In addition to this lightness, high thermal conductivity is required. In addition, it is also required to have high workability in casting processing such as die casting. In addition, it is preferable that the mechanical strength is sufficient because it is used for structural members and the like. In addition, of course, it is necessary to have high flame retardancy because it is used in equipment that is likely to generate heat (transportation equipment, etc., as described above).

An aluminum-based alloy is sometimes used as an alloy material capable of achieving both thermal conductivity and light weight.

However, although aluminum is lightweight, its lightness is still insufficient. In addition, it may be insufficient in terms of plastic workability, mechanical strength, and the like. From such a point of view, attention has been paid to magnesium, which is an element lighter than aluminum.

The room temperature density of magnesium is 1.7 g/cm3, which is about 1/4 that of iron and about 2/3 that of aluminum. Magnesium is also known to have excellent properties such as specific strength, specific rigidity, machinability, dent resistance, and vibration absorption.

Due to this lightweight property, several techniques have been proposed for magnesium-based alloys (see Patent Documents 1, 2, 3, and 4, for example).

JP 2010-116620 A Japanese Patent No. 5146767 Japanese Patent Publication No. 2018-521123 Japanese Patent Publication No. 2011-509350

In Patent Document 1, when the whole is 100% by mass, 2 to 6% Al, Ca with a composition ratio (Ca / Al) of 0.5 to 1.5, and 0.1 to 0.7% of Mn, 1 to 6% of Sr, and the balance of Mg and unavoidable impurities and/or modifying elements. Accordingly, a Mg alloy is disclosed which is excellent in high temperature properties such as creep resistance and thermal conductivity as well as normal temperature properties.

Patent Literature 1 discloses a magnesium alloy in which lightweight magnesium is used as a raw material and calcium is added to enhance flame retardancy. At this time, aluminum is added to the magnesium alloy of Patent Document 1 in order to improve corrosion resistance.

However, the addition of aluminum causes a problem of lowering thermal conductivity and mechanical strength. Therefore, the magnesium alloy disclosed in Patent Document 1 has a problem of insufficient thermal conductivity and mechanical strength.

Patent Document 2 discloses that when the total is 100% by mass, copper (Cu) is 0.5% by mass or more and 10% by mass or less, calcium (Ca) is 0.01% by mass or more and 3% by mass or less,
and the balance being magnesium (Mg) and inevitable impurities.

Similarly to Patent Document 1, Patent Document 2 also adds calcium to improve the flame retardancy of the magnesium alloy. Similarly, aluminum is added to improve corrosion resistance.

However, Patent Document 2 also has the same problem as Patent Document 1.

Patent Document 3 discloses 2.6-5.5% by weight aluminum (Al), 2.7-3.5% by weight lanthanum (La), 0.1-1.6% by weight cerium (Ce), 0.14-0.50% by weight manganese (Mn), 0.0003 ~0.0020% by weight beryllium (Be) and optionally up to 0.35% by weight zinc (Zn), up to 0.40% by weight tin (Sn), up to 0.20% by weight neodymium (Nd), and up to 0.10% by weight praseodymium A magnesium-based alloy containing (Pr) with the balance being magnesium and inevitable impurities is disclosed.

The magnesium alloy disclosed in Patent Document 3 has aluminum added in order to improve corrosion resistance. Lanthanum (La) and cerium (Ce) are added to the magnesium alloy of Patent Document 3 in order to deal with the reduction in thermal conductivity and mechanical strength due to the addition of aluminum.

However, the magnesium alloy disclosed in Patent Document 3 contains large amounts of lanthanum and cerium. For this reason, there is a problem that the range of solidification temperature is narrowed during molding into a structural member or the like by casting, etc., making it difficult to perform molding with a high degree of accuracy. That is, there is a problem of poor workability due to casting. There is also the problem of insufficient flame retardancy. Therefore, when the magnesium alloy disclosed in Patent Document 3 is used for equipment such as transportation equipment, there is a problem that the heat generation is insufficient. For this reason, there is a problem that it is difficult to apply it to equipment that has a problem of heat generation.

Patent Document 4 is a magnesium-based alloy containing, by weight, 2-5% rare earth elements (the alloy contains lanthanum and cerium as rare earth elements, and the lanthanum content is greater than the cerium content); 0.2-0. 0-0.15% aluminum; 0-0.5% yttrium or gadolinium; 0-0.2% zirconium; 0-0.3% manganese; 0-0.1% calcium; A magnesium-based alloy is disclosed consisting of beryllium, the balance being magnesium except for incidental impurities.

Patent document 4 considers flame retardancy and adds calcium. However, there is a problem that the amount of calcium added is small and insufficient to achieve flame retardancy. Similarly, aluminum is added in order to improve corrosion resistance, but this is also a very small amount, and there is a problem that the improvement in corrosion resistance is insufficient. On the other hand, lanthanum and cerium are added to ensure mechanical strength. However, the amounts of lanthanum and cerium added are large. For this reason, there is a problem that the range of solidification temperature is narrowed during molding into a structural member or the like by casting, etc., making it difficult to perform molding with a high degree of accuracy. That is, there is a problem of poor workability due to casting.

In addition, there is also a problem of increased cost due to the large amount of lanthanum, cerium, and the like added.

That is, Patent Document 4 has a problem of poor balance in flame retardancy, corrosion resistance, workability, mechanical strength, and the like.

As described above, conventional magnesium alloys have a problem of insufficient flame retardancy, corrosion resistance, workability, or mechanical strength. As a result, there was a problem that it is not suitable for casting and application to equipment is insufficient. As a result, it has a problem that it is insufficient as a substitute for existing and distributed aluminum alloys.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnesium alloy and a cast structural member using a magnesium alloy, which are suitable for flame retardancy and workability while achieving both lightness and thermal conductivity.

In view of the above problems, the magnesium alloy of the present invention contains 0.25 mass% to 1.0 mass% calcium and
2.5 mass% to 3.5 mass% aluminum with respect to the whole;
With respect to the whole, 1.0 mass% to 1.5 mass% of additive elements,
0 mass% to 0.5 mass% manganese with respect to the whole ,
consisting of the balance magnesium and unavoidable mixtures,
Said additive elements are lanthanum and cerium.

The magnesium alloy of the present invention has thermal conductivity comparable to that of conventional general-purpose aluminum alloys. In addition, it is superior in lightness to aluminum alloy. This is because the element density of magnesium itself is low, so that the weight reduction of the magnesium alloy of the present invention is realized.

In addition, the magnesium alloy of the present invention has high corrosion resistance and heat resistance, and has the advantage of being easily applied to structural members of equipment such as transportation equipment. In addition, since it is highly workable in casting processes such as die casting, it can be applied to structural members of various shapes and sizes. As a result, the range of application to various devices is widened, facilitating the spread.

As a result, there is a possibility that it will lead to mass production efficiency and associated cost reduction.

4 is a flow chart of a magnesium alloy manufacturing process according to an embodiment of the present invention. It is a mimetic diagram showing a fusion process in an embodiment of the invention. 4 is a graph showing the level of thermal conductivity when the composition ratio is changed in the embodiment of the invention. 4 is a table showing experimental results such as the thermal conductivity of magnesium alloys. FIG. 2 is a schematic diagram showing a method for measuring the tensile strength of the magnesium alloy of the present invention; 1 is a graph showing measurement results of thermal conductivity of Examples 1 to 7, which are examples of actual production of magnesium alloys of the present invention. 1 is a table showing experimental results of tensile strength and elongation for Examples 5-7 of the present invention. 1 is a graph showing experimental results of tensile strength and elongation for Examples 5-7 of the present invention.

The magnesium alloy according to the first invention of the present invention contains 0.25 mass% to 1.0 mass% calcium with respect to the whole,
2.5 mass% to 3.5 mass% aluminum with respect to the whole;
With respect to the whole, 1.0 mass% to 1.75 mass% of additive elements,
manganese and
consisting of the balance magnesium and unavoidable mixtures,
The additive elements include lanthanum and cerium.

With this configuration, it is possible to realize a magnesium alloy that achieves a good balance between lightness, flame resistance, and high thermal conductivity.

In the magnesium alloy according to the second aspect of the present invention, in addition to the first aspect, the content of calcium is 0.5 mass% to 1.0 mass% with respect to the whole.

With this configuration, a higher thermal conductivity can be achieved.

In the magnesium alloy according to the third invention of the present invention, in addition to the first or second invention, the additive element is 1.25 mass% to 1.75 mass% with respect to the whole.

With this configuration, a higher thermal conductivity can be achieved.

In the magnesium alloy according to the fourth aspect of the present invention, in addition to any one of the first to third aspects, the aluminum content is 2.5 mass% to 3.0 mass% with respect to the whole.

With this configuration, a higher thermal conductivity can be achieved.

In the magnesium alloy according to the fifth aspect of the present invention, in addition to any one of the first to fourth aspects, the manganese content is 0 mass% to 0.5 mass% with respect to the whole.

With this configuration, a higher thermal conductivity can be achieved.

The magnesium alloy according to the sixth aspect of the present invention includes approximately 0.75 mass% calcium with respect to the whole,
About 3.0 mass% aluminum with respect to the whole,
With respect to the whole, about 1.5 mass% of additive elements,
About 0.2 mass% manganese with respect to the whole,
consisting of the balance magnesium and unavoidable mixtures,
The additive elements include lanthanum and cerium.

With this configuration, it is possible to realize a magnesium alloy that achieves a good balance between lightness, flame resistance, and high thermal conductivity.

In the magnesium alloy according to the seventh aspect of the present invention, calcium of approximately 0.75 mass% with respect to the whole,
Approximately 2.5 mass% aluminum with respect to the whole,
With respect to the whole, about 1.5 mass% of additive elements,
About 0.2 mass% manganese with respect to the whole,
consisting of the balance magnesium and unavoidable mixtures,
The additive elements include lanthanum and cerium.

With this configuration, it is possible to realize a magnesium alloy that achieves a good balance between lightness, flame resistance, and high thermal conductivity.

A magnesium alloy according to an eighth aspect of the present invention, in addition to any one of the first to seventh aspects, further includes an additional element group,
The additional element group includes silicon (Si), beryllium (Be), zirconium (Zr), tin (Sn), lithium (Li), silver (Ag), copper (Cu), yttrium (Y), and neodymium (Nd). , gadolinium (Gd), strontium (Sr), and dysprosium (Dy).

This configuration allows for further variations.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)

(Description of reference technology)
Currently, there is an aluminum alloy ADC12 that has already been put into practical use. This aluminum alloy is lightweight and has excellent thermal conductivity. Due to its excellent thermal conductivity, it has the advantage of facilitating heat dissipation even when used for housings, members, and parts of various equipment and devices such as electronic equipment and transportation equipment.

Such existing aluminum alloys have a thermal conductivity of 90 W/m·K or higher.

With a thermal conductivity of 90 W/m·K or more, this aluminum alloy easily conducts heat even in equipment and devices that easily generate heat, such as electronic equipment and transportation equipment. If the heat can be easily conducted, the heat of the heat-generating part can be easily discharged to the outside. If it is easy to discharge, it is easy to solve the problem of heat generated while equipment and devices are used.

Existing aluminum alloys have a thermal conductivity of 90 W/m·K or higher to solve such heat problems. At this time, the thermal conductivity of the aluminum alloy ADC 12 described above should be 90 W/m·K or more as a guideline.

From this point, it is suitable that the magnesium alloy of the present invention has a thermal conductivity of 90 W/m·K or more as a standard. Here, the aluminum alloy with ADC 12 has the following composition. 9.6-12.0 mass% silicon, 1.5-3.5 mass% copper, 0.3 mass% or less magnesium, 1.0 mass% or less zinc, 1.3 mass% or less iron, 0.5 mass% The following manganese, 0.5 mass% or less nickel, 0.2 mass% or less tin, 0.2 mass% or less lead, 0.3 mass% or less titanium, and the balance aluminum. This is defined in JIS H5302.

According to disclosure by the Japan Die Casting Association, the thermal conductivity of the aluminum alloy of the ADC 12 is 96 W/m·K or higher. Taking this into account, it can be seen that the thermal conductivity of the magnesium alloy of the present invention, which is intended to replace existing aluminum alloys, should be 90 W/m·K or more.

(magnesium alloy)
The magnesium alloy of the present invention has the following composition.
0.25 mass% to 1.0 mass% calcium with respect to the whole,
2.5 mass% to 3.5 mass% aluminum with respect to the whole;
With respect to the whole, 1.0 mass% to 1.75 mass% of additive elements,
manganese and
consisting of the balance magnesium and unavoidable mixtures,
Additive elements include lanthanum and cerium.

As described above, magnesium alloys contain magnesium, calcium, aluminum, manganese, and additional elements. Here, lanthanum and cerium are included as additive elements. At this time, it is not excluded that the magnesium alloy contains unavoidable mixtures that are unavoidably mixed in the origin of raw materials, manufacturing processes, and the like.

In addition, it does not exclude the addition of ingredients that do not interfere with the properties and properties of magnesium alloys and the intent of the invention. For example, ingredients other than those mentioned above may be added, but may not interfere with the properties or intentions of the magnesium alloy of the present invention. This is the case where the thermal conductivity of the magnesium alloy is not hindered.

The composition ratio of calcium (hereinafter referred to as "Ca" as necessary) is 0.25 mass% to 1.0 mass% with respect to the whole. The composition ratio of aluminum (hereinafter referred to as “Al” as necessary) is 2.5 mass % to 3.5 mass % with respect to the whole. Additive elements including lanthanum (hereinafter referred to as "La" as necessary) and cerium (hereinafter referred to as "Ce" as necessary) are 1.0 mass% to 1.75 mass% of the whole. The magnesium alloy of the present invention contains manganese (hereinafter referred to as "Mn" as necessary) and the balance is magnesium.

As will be described later, the composition ratio of manganese may be 0 mass % to 0.5 mass % with respect to the whole.

Magnesium alloys are manufactured with respective compositions corresponding to these composition ratios.

FIG. 1 is a flow chart of manufacturing steps of a magnesium alloy according to an embodiment of the present invention.

As shown in the flowchart of FIG. 1, a magnesium alloy is manufactured through a weighing process ST1, a melting process ST2, a solidification process ST3, and a molding process ST4. Of course, FIG. 1 shows the main steps in the manufacturing process, and there is no problem even if other steps are added to manufacture the magnesium alloy.

In the weighing step ST1, calcium, aluminum, magnesium, additive elements, and manganese are weighed so as to achieve the composition ratios as described above. The unavoidable mixture may be included depending on the purity of raw materials such as zinc, or may be included by mixing in the weighing step ST1 or the like.

In the melting step ST2, each weighed raw material is melted in a melting container. FIG. 2 is a schematic diagram showing the melting process in the embodiment of the present invention. Calcium, aluminum, magnesium, additional elements, and manganese, which are weighed raw materials, are charged into the melting vessel 100 . These raw materials put into the melting vessel 100 are melted by heating.

The molten metal obtained through the melting step ST2 is solidified by cooling. This is the solidification step ST3. A solidified alloy is obtained by being solidified by cooling in the solidification step ST3.

Next, a molding step ST4 (for example, it may be performed after the solidification step ST3, or the molding step ST4 may be performed in parallel with the solidification step ST3) as necessary. Through this molding step ST4, for example, an ingot-shaped magnesium alloy is manufactured.

Of course, additional steps may be performed after the molding step ST4.

The magnesium alloy manufactured in this way has a high lightness because the main raw material is magnesium. As indicated by the atomic number, it is lighter than an aluminum alloy containing aluminum as the main component if the composition ratio is the same. Moreover, a magnesium alloy having this composition ratio has a high thermal conductivity.

The thermal conductivity of this magnesium alloy is 90 W/m·K or more, as is clear from the experimental results described later. With a thermal conductivity of 90 W/m·K or more, it can be used for casings, members, and parts of various devices and devices in place of the aluminum alloys described in the reference technology. This magnesium alloy is lighter than an aluminum alloy and has a thermal conductivity equal to or greater than that of an aluminum alloy. Therefore, this magnesium alloy can be used as a substitute in fields where aluminum alloys have been used for weight reduction.

This alternative use can result in greater weight savings. In fields where aluminum alloys have conventionally been used, the use of lighter magnesium alloys has made it possible to reduce the weight of equipment and devices. Electronic devices have the advantage of being more mobile, and transportation devices have the advantage of improved fuel efficiency.

In addition, it has a thermal conductivity of 90 W/m·K or higher, which is equivalent to that of aluminum alloys currently in use. For this reason, magnesium alloys can be suitably used in electronic equipment and transportation equipment that must solve the problem of heat generation.

As mentioned above, the thermal conductivity of 90 W/m·K or more is based on the thermal conductivity of aluminum alloys that are currently in use. Can be used as an alternative.

Here, the magnesium alloy of the present invention improves heat resistance by containing calcium. In addition, the thermal conductivity is also improved. However, the addition of calcium improves these heat resistances and thermal conductivity, but may reduce the mechanical properties. Addition of aluminum improves mechanical properties and durability. However, the addition of aluminum has a demerit that hinders improvement in thermal conductivity. Correspondingly, the inclusion of additive elements including lanthanum and cerium can improve the thermal conductivity that can be degraded by the addition of aluminum.

As described above, the magnesium alloy of the present invention has a composition and a composition ratio that achieve a good balance between heat resistance, thermal conductivity, and mechanical strength such as durability. With such a composition and composition ratio, the magnesium alloy of the present invention achieves well-balanced heat resistance, thermal conductivity, and mechanical strength, and also has the lightness of magnesium. Realized.

Such magnesium alloys are suitable for replacement in fields where aluminum alloys and other alloys have traditionally been used.

Further, on the premise of the composition and composition ratio of the magnesium alloy described above, more detailed variations of the magnesium alloy will be described.

(Magnesium alloy 1)
As the magnesium alloy 1, it is also preferable that calcium is 0.5 mass% to 1.0 mass% with respect to the whole. Other compositions are included in the magnesium alloys mentioned above.

By setting the composition ratio of calcium to a more specific range in this way, the thermal conductivity of the obtained magnesium alloy 1 increases. By further increasing the thermal conductivity, it can be suitably used in various parts and structural parts that require heat resistance. This is because if the thermal conductivity is high, even if heat is generated in the parts or structural parts that are used, the high thermal conductivity will allow the heat to escape early, making it less likely to be adversely affected by the heat. .

FIG. 3 is a graph showing the level of thermal conductivity when changing the composition ratio in the embodiment of the present invention. The left side of FIG. 3 shows a magnesium alloy in which the content of aluminum is fixed at 3.0 mass%, and calcium and additional elements (indicated as Mm (misch metal) in the figure) are added within the range of the magnesium alloy described above. 1 is a graph showing varying levels of thermal conductivity of magnesium alloys.

The right side of FIG. 3 is a graph showing the thermal conductivity level of the magnesium alloy when the content of the additive element is fixed at 1.5 mass% and the composition range of calcium and aluminum is changed. be. In the graph of FIG. 3, square marks indicate a thermal conductivity of 90 W / m K or more, circle marks indicate a thermal conductivity of 92.5 W / m K or more, and double circles. indicates that the thermal conductivity is 95.0 W/m·K or more. That is, it indicates the level of thermal conductivity. A double circle is the state with the highest level.

On the left side of FIG. 3, when calcium is 0.5 mass% to 1.0 mass%, the thermal conductivity is either a circle or a double circle, indicating that the thermal conductivity is higher. It is shown. The right side of FIG. 3 also has the same tendency.

From this point, it can be seen that a calcium content of 0.5 mass % to 1.0 mass % can achieve a higher thermal conductivity, although it depends on other composition ratios. In this regard, the magnesium alloy 1 containing 0.5 mass % to 1.0 mass % of calcium relative to the whole is included in the magnesium alloy of the present invention, and can further increase the thermal conductivity.

(Magnesium alloy 2)
Magnesium alloy 2 contains 1.25 mass% to 1.75 mass% of additive elements including lanthanum and cerium. Other compositions are included in the magnesium alloys mentioned above.

By specifying the additive element to be 1.25 mass % to 1.75 mass % with respect to the whole as described above, the magnesium alloy 2 can further increase its thermal conductivity. In the magnesium alloy of the present invention described above, the additive element has a ratio of 1.0 mass% to 1.75 mass% with respect to the whole. Magnesium alloy 2 is a more specific range of this range and is a range included in this magnesium alloy.

Thus, by setting the additive element to 1.25 mass % to 1.75 mass % with respect to the whole, the level of thermal conductivity increases as shown on the left side of FIG. It can be seen that the thermal conductivity tends to increase when the composition ratio of the additive element is 1.25 mass % to 1.75 mass % with respect to the whole, although it depends on changes in other composition elements.

The right side of FIG. 3 shows the case where the additive element content, which is the median value, is 1.5 mass %. In this case, it also shows that the thermal conductivity tends to be high, although it varies depending on the content of other compositions. Thus, the magnesium alloy 2, in which the additive element is specified to be 1.25 mass% to 1.75 mass% with respect to the whole, can raise the level of thermal conductivity.

(Magnesium alloy 3)
Magnesium alloy 3 is specified in the composition ratio of the magnesium alloy of the present invention so that aluminum is 2.5 mass% to 3.0 mass% with respect to the whole. The content of aluminum is more specified.

The magnesium alloy 3 can further increase the thermal conductivity by specifying the composition ratio of aluminum more precisely. In the graph on the right side of FIG. 3, aluminum is 2.5 mass % to 3.0 mass % with respect to the whole, so the level of thermal conductivity is high. Although it varies depending on the contents of other compositions, the thermal conductivity tends to be higher than when aluminum is 3.5 mass%. For this reason, the magnesium alloy 3 in which aluminum is 2.5 mass% to 3.0 mass% with respect to the whole can realize a higher thermal conductivity among the magnesium alloys of the present invention.

Of course, even if the magnesium alloys 1-3 do not, the magnesium alloy of the present invention has the desired level of thermal conductivity. However, it is also suitable for realizing a magnesium alloy with a higher thermal conductivity to specify a partial composition ratio as in the magnesium alloys 1 to 3.

(manganese)
Manganese is preferably 0 mass% to 0.5 mass% with respect to the whole. Manganese itself does not adversely affect the properties of magnesium alloys. On the other hand, it is also suitable to contain from the viewpoint of improving the mechanical strength and increasing the ease of manufacturing.

On the other hand, too much manganese content is also undesirable.

Therefore, the content of manganese is preferably 0 mass% to 0.5 mass% with respect to the whole.

(Magnesium alloy 4)
Magnesium alloy 4 is
Approximately 0.75 mass% calcium with respect to the whole,
About 3.0 mass% aluminum with respect to the whole,
With respect to the whole, about 1.5 mass% of additive elements,
About 0.2 mass% manganese with respect to the whole,
consisting of the balance magnesium and unavoidable mixtures,
The additive element has a composition that includes lanthanum and cerium.

Magnesium alloy 4 has a composition included in the magnesium alloy of the present invention, and has a specified composition ratio of constituent calcium, aluminum, additional elements, and manganese.

Magnesium alloy 4 has an electrical conductivity of 24.2 (IACS %) and a thermal conductivity of 93 W/mK, as described later (Example 6 described later). Electrical conductivity has a close correlation with thermal conductivity. Comprehensively considering the electrical conductivity and thermal conductivity of the magnesium alloy 4, it can be seen that the magnesium alloy 4 can exhibit suitable performance at the composition ratio included in the magnesium alloy of the present invention. Among the magnesium alloys of the present invention, the magnesium alloy 4 having a composition ratio that produces high merits can be suitably substituted for conventional aluminum alloys and the like.

(Magnesium alloy 5)

Magnesium alloy 5 is
Approximately 0.75 mass% calcium with respect to the whole,
Approximately 2.5 mass% aluminum with respect to the whole,
With respect to the whole, about 1.5 mass% of additive elements,
About 0.2 mass% manganese with respect to the whole,
consisting of the balance magnesium and unavoidable mixtures,
The additive element has a composition including lanthanum and cerium.

Magnesium alloy 5 has a composition included in the magnesium alloy of the present invention, and has a specified composition ratio of constituent calcium, aluminum, additional elements, and manganese.

Magnesium alloy 4 has an electrical conductivity of 24.9 (IACS %) and a thermal conductivity of 98 W/mK, as described later (Example 7 described later). Electrical conductivity has a close correlation with thermal conductivity. Comprehensively considering the electrical conductivity and thermal conductivity of the magnesium alloy 4, it can be seen that the magnesium alloy 5 can exhibit suitable performance at the composition ratio included in the magnesium alloy of the present invention. Among the magnesium alloys of the present invention, the magnesium alloy 5 having a composition ratio that produces high merits can be suitably substituted for conventional aluminum alloys and the like.

The thermal conductivity of the magnesium alloy having the above composition is 90 W/m·K or more. With a thermal conductivity of 90 W/m·K or more, it can be used for casings, members, and parts of various devices and devices in place of the aluminum alloys described in the reference technology. This magnesium alloy 1 is lighter than the aluminum alloy and has thermal conductivity equal to or higher than that of the aluminum alloy. Therefore, this magnesium alloy can be used as a substitute in fields where aluminum alloys have been used for weight reduction.

This alternative use can result in greater weight savings. In fields where aluminum alloys have conventionally been used, the use of lighter magnesium alloys has made it possible to reduce the weight of equipment and devices. Electronic devices have the advantage of being more mobile, and transportation devices have the advantage of improved fuel efficiency.

In addition, it has a thermal conductivity of 90 W/m·K or higher, which is equivalent to that of aluminum alloys currently in use. For this reason, magnesium alloys can be suitably used in electronic equipment and transportation equipment that must solve the problem of heat generation.

(Mode of use)
Magnesium alloys 1 to 4 described above are used for applications such as housings, members, structural materials, and parts of electronic devices. For example, it is used for the housing of notebook computers and tablet terminals, as well as for internal structural materials. Alternatively, it is used for parts and members of mobile terminals.

It is also used for structural materials and parts of transportation equipment. For example, it is used for parts such as axles and screws of transportation equipment, and parts of structural materials such as chassis. This is because all of these need to solve the problem of heat and the problem of weight reduction.

In addition to electronic equipment and transportation equipment, it is also used for housings, parts, members, structural materials, etc. of various devices used in precision equipment and factories. This is because, in these cases as well, it is required to reduce the weight while maintaining the exhaust heat efficiency.

(Cast structural member using magnesium alloy)
Cast structural members using magnesium alloys as described above are also applications of magnesium alloys. This is the case where a magnesium alloy is cast and then molded and applied to various structural members.

This cast structural member is used for internal combustion engines, transmission engines, pistons, shafts, connecting rods, covers, cylinders, cylinder blocks, arms, knuckles, pillars, wheels, and compressors in any of automobiles, motorcycles, aircraft, ships, and railway vehicles. At least one of a housing, a steering, an internal housing, an engine mount, an oil pan, a gear, a gear case, nuts, screws, bolts, and a heat sink for the LED lighting device.

It is also suitable for use in parts that require heat conduction, such as those used in electric vehicles. For example, it is used for inverter cases, converter cases, water cooling devices, water jackets, heat pipes, and the like.

By using magnesium alloys for cast structural members for these applications, even if problems such as heat generation occur, they can be discharged with high thermal conductivity. As a result, it can be suitably used even in fields where heat generation is possible. In addition, by using magnesium alloy cast structural members for these applications, it is possible to further reduce the weight, thereby realizing low fuel consumption, low energy consumption, and the like.

(additional element group)

It is also preferred that the above magnesium alloys of the present invention (including magnesium alloys 1, 2, etc.) further contain additional elements.

Additional element groups include silicon (Si), beryllium (Be), zirconium (Zr), tin (Sn), lithium (Li), silver (Ag), copper (Cu), yttrium (Y), and neodymium (Nd). , gadolinium (Gd), strontium (Sr), and dysprosium (Dy).

The inclusion of these additional elements does not interfere with the objectives of the present invention, such as thermal conductivity and light weight. On the other hand, the addition of these additional elements may also have the advantage of improving the mechanical strength. Alternatively, depending on the composition of the raw materials used in the manufacturing process, these additional elements may be included or may be included due to the convenience of the manufacturing process.

These additional elements may also be included for other reasons.

Even when these additional elements are included, if they are present in trace amounts, they do not affect the main functions such as the thermal conductivity of the magnesium alloy of the present invention. Therefore, even when these additional elements are included, they are included in the magnesium alloy of the present invention.

Further, by adding these additional elements, depending on the additional elements, it is possible to improve the mechanical strength and durability as described above. For this reason, it is also preferred that any of the additional elements are added, if desired.

The total amount of the trace amount of additional elements added is 1.0 mass % or less with respect to the whole. Therefore, any one or a combination of two or more of the additional elements described above may be added.

(Explanation of experimental results)
The inventor conducted experiments on the magnesium alloy of the present invention. Through this experiment, the present invention was confirmed.

(Experiment 1: Measurement of thermal conductivity)
The inventor measured the thermal conductivity of magnesium alloys. A magnesium alloy was produced which was calcium, aluminum, additional elements, manganese and the balance magnesium. At this time, magnesium alloys were manufactured with different compositions, and the thermal conductivity of each magnesium alloy was measured. Through this measurement, the compositional range was confirmed to have a thermal conductivity of 90 W/m·K or higher, which was the initial criterion.

FIG. 4 is a table showing experimental results such as the thermal conductivity of magnesium alloys. The table in FIG. 4 shows the thermal conductivity measured while changing the composition ratio of calcium, aluminum, additional elements, manganese and the balance magnesium. At this time, the thermal conductivity was measured after measuring the electrical conductivity having a correlation with the thermal conductivity. In addition, the tensile strength is also shown in the table of FIG.

The electric conductivity was measured by attaching an electric terminal to the produced magnesium alloy sample using AutoSigma3000 manufactured by Hocking. Thermal conductivity was measured using LFA447, a thermal constant measurement system manufactured by NETASCH.

Here, there is a correlation between the electrical conductivity and the thermal conductivity. Therefore, in the experiment in FIG. 4, electrical conductivity and thermal conductivity are measured. Electrical conductivity measurements are as described above. The thermal conductivity was measured using the above-described equipment as follows.
(Method for measuring thermal conductivity)
Measurement equipment name: thermal constant measurement device (manufacturer, model number: NETZSCH, LFA447)
Measurement conditions: Measurement temperature = 20°C
: Measurement sample size=φ10×2 mm thickness Measurement constant : Thermal diffusivity, specific heat, thermal conductivity A heat source is added to the sample, thermal diffusivity and specific heat are measured, and thermal conductivity is calculated from these.

The tensile strength was measured using a device for measuring tensile strength after forming a magnesium alloy test piece into a predetermined shape. FIG. 5 is a schematic diagram showing a method for measuring the tensile strength of the magnesium alloy of the present invention. A test piece having the shape shown in FIG. 5 is prepared, and the test piece is pulled using a 300 kN universal testing machine manufactured by Tokyo Shikenki Co., Ltd. At this time, the durability state of the test piece (pressure at break of the test piece) was confirmed, and the tensile strength was measured.
(Method for measuring tensile strength)
Measuring equipment name: 300kN universal testing machine (manufacturer, model number: Tokyo Testing Machine Co., Ltd., AY-300P)
Measurement conditions: Measurement temperature = 20°C
: Parallel part of test piece = diameter 6 mm, length 45 mm

(Experimental results of electrical conductivity)

The measurement results of electrical conductivity and thermal conductivity are described in order from the upper left of the table in FIG. Numerals described in the table of FIG. 4 and the graph of FIG. 6, which will be described later, indicate respective examples.

(Example 1)
The magnesium alloy of Example 1 contains 3.0 mass% aluminum, 0.75 mass% calcium, 1.0 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 1 are as follows.

Electrical conductivity: 21.8 (IACS%)
Thermal conductivity: 94W/mK

The magnesium alloy of Example 1 is a magnesium alloy contained in the composition and composition ratio as described above. In particular, it is a magnesium alloy corresponding to magnesium alloy 1 described above. The magnesium alloy of Example 1 has a thermal conductivity exceeding the standard of 90 W / mK, and from the experimental results of Example 1, the composition and composition ratio of the magnesium alloy of the present invention are the target thermal conductivity It was confirmed to have a rate.

(Example 2)
The magnesium alloy of Example 2 contains 3.0 mass% aluminum, 0.75 mass% calcium, 1.25 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 2 are as follows.

Electrical conductivity: 22.6 (IACS%)
Thermal conductivity: 96W/mK

The magnesium alloy of Example 2 is a magnesium alloy contained in the composition and composition ratio as described above. In particular, it is a magnesium alloy corresponding to magnesium alloy 2 described above. The magnesium alloy of this Example 2 has a thermal conductivity exceeding the reference value of 90 W/mK. It was confirmed to have a rate.

(Example 3)
The magnesium alloy of Example 3 contains 3.0 mass% aluminum, 0.25 mass% calcium, 1.5 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 3 are as follows.

Electrical conductivity: 21.9 (IACS%)
Thermal conductivity: 90W/mK

The magnesium alloy of Example 3 is a magnesium alloy contained in the composition and composition ratio as described above. The magnesium alloy of this Example 3 has a thermal conductivity exceeding the reference value of 90 W/mK. It was confirmed to have a rate.

(Example 4)
The magnesium alloy of Example 4 contains 3.0 mass% aluminum, 0.5 mass% calcium, 1.5 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 4 are as follows.

Electrical conductivity: 22.6 (IACS%)
Thermal conductivity: 97W/mK

The magnesium alloy of Example 4 is a magnesium alloy contained in the composition and composition ratio as described above. In particular, it is a magnesium alloy corresponding to magnesium alloy 3 described above. The magnesium alloy of Example 2 has a thermal conductivity exceeding the standard of 90 W / mK, and from the experimental results of Example 4, the composition and composition ratio of the magnesium alloy of the present invention are the target thermal conductivity It was confirmed to have a rate.

(Example 5)
The magnesium alloy of Example 5 contains 3.5 mass% aluminum, 0.75 mass% calcium, 1.5 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 5 are as follows.

Electrical conductivity: 22.0 (IACS%)
Thermal conductivity: 90W/mK

The magnesium alloy of Example 5 is a magnesium alloy contained in the composition and composition ratio as described above. The magnesium alloy of Example 5 has a thermal conductivity exceeding the standard of 90 W/mK, and the experimental results of Example 5 also show that the composition and composition ratio of the magnesium alloy of the present invention are the target thermal conductivity It was confirmed to have a rate.

(Example 6)
The magnesium alloy of Example 6 contains 3.0 mass% aluminum, 0.75 mass% calcium, 1.5 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 6 are as follows. Here, Example 6 corresponds to magnesium alloy 4 described above.

Electrical conductivity: 24.2 (IACS%)
Thermal conductivity: 93W/mK

The magnesium alloy of Example 6 is a magnesium alloy contained in the composition and composition ratio as described above. The magnesium alloy of this Example 6 has a thermal conductivity exceeding the reference value of 90 W/mK. It was confirmed to have a rate.

(Example 7)
The magnesium alloy of Example 7 contains 2.5 mass% aluminum, 0.75 mass% calcium, 1.5 mass% additional elements, 0.2 mass% manganese, and the balance magnesium. Experimental results for the magnesium alloy of Example 7 are as follows. Here, Example 7 corresponds to magnesium alloy 5 described above.

Electrical conductivity: 24.9 (IACS%)
Thermal conductivity: 98W/mK

The magnesium alloy of Example 7 is a magnesium alloy contained in the composition and composition ratio as described above. The magnesium alloy of this Example 7 has a thermal conductivity exceeding the reference value of 90 W/mK. It was confirmed to have a rate.

Moreover, it can be seen that the inclusion of additive elements including lanthanum and cerium eliminates the decrease in thermal conductivity due to the inclusion of aluminum and raises the thermal conductivity to a sufficient level.

FIG. 6 is a graph showing the measurement results of the thermal conductivity of Examples 1 to 7, which are practical examples of manufacturing the magnesium alloy of the present invention. FIG. 6 shows a graph of the thermal conductivity results of Examples 1 to 7 described with reference to FIG.

As is clear from the graph in FIG. 6, all of Examples 1 to 7 have a standard thermal conductivity of 90 W/mK or higher. Therefore, it was also confirmed from experiments that magnesium alloys (including magnesium alloys 1 and 2, etc.) having the compositions and composition ratios described above have sufficient thermal conductivity. In addition, weight reduction can be achieved by using magnesium as the main component. As a result, in addition to weight reduction, it can be applied in various fields where heat generation must be dealt with.

(Confirmation of tensile strength)
Also, for Examples 5 to 7, the tensile strength of the manufactured magnesium alloy was measured. FIG. 7 is a table showing experimental results of tensile strength and elongation for Examples 5-7 of the present invention. FIG. 8 is a graph showing experimental results of tensile strength and elongation for Examples 5-7 of the present invention.

The method for measuring the tensile strength is as described above.

The tensile strength of Example 5 is 228.7 MPa and the elongation is 7.8%.

The tensile strength of Example 6 is 225.8 MPa and the elongation is 9.4%.

The tensile strength of Example 7 is 215.7 MPa and the elongation is 5.8%.

Both have sufficient tensile strength and elongation. Having this level of tensile strength and elongation provides sufficient ductility in molding and the like. Sufficient ductility facilitates molding into various shapes while ensuring sufficient durability.

As a result, the cast structural member using the magnesium alloy of the present invention also has improved easiness and accuracy in manufacturing.

It should be noted that the magnesium alloy described in the embodiment is merely an example for explaining the gist of the present invention, and includes modifications and alterations within the scope of the gist of the present invention.

100 melting vessel

Claims (9)

0.25 mass% to 1.0 mass% calcium with respect to the whole,
2.5 mass% to 3.5 mass% aluminum with respect to the whole;
With respect to the whole, 1.0 mass% to 1.5 mass% of additive elements,
0 mass% to 0.5 mass% manganese with respect to the whole ,
consisting of the balance magnesium and unavoidable mixtures,
A magnesium alloy, wherein the additive elements are lanthanum and cerium. 2. The magnesium alloy according to claim 1, wherein said calcium is 0.5 mass % to 1.0 mass % with respect to the whole. 3. The magnesium alloy according to claim 1, wherein said additive element is 1.25 mass % to 1.5 mass % with respect to the whole. The magnesium alloy according to any one of claims 1 to 3, wherein said aluminum is 2.5 mass% to 3.0 mass% with respect to the whole. 0.75 mass% calcium with respect to the whole,
With respect to the whole, 3.0 mass% aluminum,
1.5 mass% additive element with respect to the whole,
With respect to the whole, 0.2 mass% manganese,
consisting of the balance magnesium and unavoidable mixtures,
A magnesium alloy, wherein the additive elements are lanthanum and cerium. 0.75 mass% calcium with respect to the whole,
2.5 mass% aluminum with respect to the whole,
1.5 mass% additive element with respect to the whole,
With respect to the whole, 0.2 mass% manganese,
consisting of the balance magnesium and unavoidable mixtures,
A magnesium alloy, wherein the additive elements are lanthanum and cerium. 7. The magnesium alloy according to any one of claims 1 to 6 , wherein said magnesium alloy has a thermal conductivity of 90 W/m·K or more. A cast structural member using a magnesium alloy according to any one of claims 1 to 7 . The cast structural member is used in any one of automobiles, motorcycles, aircraft, ships, and railway vehicles,
Internal combustion engine, transmission engine, piston, shaft, connecting rod, cover, cylinder, cylinder block, arm, knuckle, pillar, wheel, compressor housing, steering, internal housing, engine mount, oil pan, gear, gear case, nut, 9. The magnesium alloy cast structural member of claim 8 , comprising at least one of a screw, a bolt and a heat sink of an LED lighting device.