WO2023090127A1

WO2023090127A1 - Alloy, alloy member, device, and alloy production method

Info

Publication number: WO2023090127A1
Application number: PCT/JP2022/040375
Authority: WO
Inventors: 慶一石塚; 淳一坂本; 広与田宮
Original assignee: キヤノン株式会社
Priority date: 2021-11-19
Filing date: 2022-10-28
Publication date: 2023-05-25
Also published as: US20240279781A1; JP2023075682A; EP4435126A1; CN118234881A

Abstract

This alloy contains Mg and Li, with the sum of the Mg content and the Li content being at least 90 mass%. The Li content of the alloy is in the range larger than 11 mass% but not more than 13.5 mass%, and the alloy contains at least one element selected from a first group consisting of Ge, Mn, and Si. The alloy has an α-phase at 25°C.

Description

Alloys, alloy members, equipment, and methods of manufacturing alloys

The present disclosure relates to Mg-Li alloys, alloy members, devices, and methods of manufacturing alloy members.

　Magnesium-based alloys are used in various devices because they are lightweight and have excellent damping properties and specific strength. In recent years, there has been a demand for further weight reduction of equipment, and magnesium-lithium alloys (Mg-Li alloys), which have a lower specific gravity than magnesium alloys, have attracted attention. Patent Document 1 discloses a magnesium-lithium alloy in which the content of lithium is in the range of 8% by mass or more and 11% by mass or less.

JP-A-2004-156089

The higher the Li content, the lighter the magnesium-lithium alloy, but the higher the Li content, the lower the corrosion resistance.

A first aspect for solving the above problems is an alloy containing Mg and Li, wherein the sum of the Mg content and the Li content is 90% by mass or more, and the Li content is in the range of more than 11% by mass and 13.5% by mass or less, the alloy contains one or more elements selected from the first group consisting of Ge, Mn and Si, and the alloy contains at 25 ° C. An alloy characterized by having an α phase.

A second aspect for solving the above problems is an alloy containing Mg and Li, wherein the sum of the Mg content and the Li content is 90% by mass or more, and the Li content of the alloy is The content is in the range of 5.34% by mass or more and 11% by mass or less, the alloy contains one or more elements selected from the first group consisting of Ge, Mn and Si, and the temperature of the alloy at 25 ° C. The alloy is characterized by satisfying y>0.3736x ² −24.053x+217.79, where y (%) is the proportion of α phase at temperature and x (mass %) is the content of Li.

A third aspect for solving the above problems contains Mg and Li, contains one or more elements selected from the first group consisting of Ge, Mn and Si, the Mg content and the Li A preparation step of preparing a raw material having a sum of contents of 90% by mass or more, a heating step of heating the raw material to 600 ° C. or higher to melt it, and a cooling step of cooling and solidifying the molten raw material. and in the cooling step, the cooling rate from the start of solidification of the molten raw material to 100° C. is 100° C./min or less.

According to the present disclosure, it is possible to provide a magnesium-lithium alloy that contains an α phase even if the Li content is more than 11% by mass, and that is lightweight and has excellent corrosion resistance.

In addition, when the Li content is in the range of 5.34% by mass or more and 11% by mass or less, it is possible to provide a magnesium-lithium alloy with a higher α-phase content than conventional alloys, which is lightweight and excellent in corrosion resistance.

1 is a schematic diagram of an alloy member according to a first embodiment; FIG. It is a schematic diagram of the apparatus concerning a 3rd embodiment. It is a schematic diagram of the equipment concerning a 4th embodiment. It is a schematic diagram of the apparatus concerning a 5th embodiment. FIG. 4 is a diagram showing the results of 2θ-θ measurement in Example 1-1; It is a figure which shows the abundance ratio of the (alpha) phase of an Example.

The embodiments of the present disclosure will be described below.

(First embodiment)
[Alloy material]
FIG. 1 is a schematic diagram of the alloy member according to the first embodiment, and is a cross-sectional view cut in the lamination direction.

The alloy member 100 is a magnesium-lithium alloy member (Mg-Li alloy member). The alloy member includes a base material 102 and a coating 101 provided on the base material 102 . The film 101 is provided to protect the first surface 102A of the substrate, and can be made of, for example, a material containing magnesium phosphate or magnesium fluoride. Further, a coating film such as a primer or a topcoat layer may be provided on the film 101 according to the purpose of the user. Examples of the coating film include a heat shielding film having a heat shielding function. However, depending on the purpose of use, the film 101 may be omitted. Therefore, in the present disclosure, the aspect without the coating 101 is also referred to as the Mg—Li alloy member.

The shape of the base material 102 is not particularly limited as long as it has the first surface 102A. The shape is not limited to the hexahedron such as the rectangular parallelepiped and the cube shown in FIG. Also, since the first surface 102A is an arbitrary surface, its location is not particularly limited.

The base material 102 contains a magnesium-lithium alloy (Mg-Li alloy). In the present disclosure, an Mg—Li alloy refers to an alloy containing Mg and Li, and the sum of the Mg content and the Li content is 90% by mass or more. When the sum of the Mg content and the Li content is 90% by mass or more, the specific gravity can be easily made 1.60 or less. Mg—Li alloys are lightweight metal materials, and are superior in light weight, vibration damping properties, and specific strength as compared to Li-free Mg alloys. Being excellent in damping means quickly converging vibration by quickly converting vibration energy into thermal energy. Further, the specific strength is the tensile strength per density, and the higher the specific strength, the lighter the member. On the other hand, if the sum of the contents of Mg and Li is less than 90% by mass, the specific gravity exceeds 1.60, making it difficult to reduce the weight. In addition, a more preferable specific gravity is 1.50 or less.

It is known that Mg-Li alloys have different crystal structures depending on the Li content. The structure is based on the phase diagram described in the document ""Binary alloy phase diagram collection", edited by Seizo Nagasaki and Makoto Hirabayashi, publisher: Agne Technical Center, ISBN-13: 978-4900041882, release date: 2001/01" According to this phase diagram, the Mg—Li alloy has a single-phase region of α phase, a single-phase region of β-phase, and a eutectic region having both α-phase and β-phase. The α phase is rich in Mg and is also called a hexagonal close-packed phase, and its crystal structure is a hexagonal close-packed (hcp) structure.The β phase is rich in Li and is also called a body-centered cubic phase, and its crystal The structure is a bcc (Body-Centered Cubic) structure.If the Li content is lower than 5.34% by mass at 25° C., only the α phase is present.Also, at 25° C., Li is 5.34 mass%. % or more and 11% by mass or less, a mixed phase of α phase and β phase occurs, and when Li exceeds 11% by mass at 25° C., only β phase occurs.

Since the Mg-Li alloy becomes lighter as the Li content increases, it is desirable to increase the Li content. However, if the conventional Mg—Li alloy is a β-phase single phase with a Li content of 11% by mass or more, it will rapidly corrode simply by being left in an environment at room temperature (for example, 25° C.) for a long time. There was a problem. Therefore, it has been necessary to improve the corrosion resistance of Mg—Li alloys.

Therefore, as a result of intensive studies by the inventors of the present application, they have found a means for increasing the content of the α phase compared to conventional methods. Specifically, a specific element is added to the Mg-Li alloy, and when cooling after melt synthesis, the molten raw material starts to solidify and is slowly cooled to 100°C, which is just below the recrystallization temperature. found a way.

The specific element to be contained in the Mg-Li alloy is one or more elements selected from the first group consisting of Ge, Mn and Si. Although the detailed mechanism has not been completely elucidated, from the experimental results including the examples described later, it is believed that these first group elements play a role in generating the α phase.

The content of Ge in the Mg-Li alloy is preferably 0.3% by mass or less. When the Ge content is 0.3% by mass or less, the corrosion resistance is particularly good. On the other hand, if the Ge content exceeds 0.3% by mass, Ge oxide may segregate at the grain boundaries of the Mg—Li alloy. From the viewpoint of improving the toughness, the Ge content is more preferably in the range of 0.01% by mass or more and 0.1% by mass or less.

The content of Mn in the Mg--Li alloy is preferably 2% by mass or less. When the Mn content is 2% by mass or less, the toughness is good. On the other hand, if the Mn content exceeds 2% by mass, the corrosion resistance may become comparable to that when Mn is not contained. A more preferable Mn content is 1.5% by mass or less. A more preferable Mn content is in the range of 0.1% by mass or more and 1.1% by mass or less.

The content of Si in the Mg--Li alloy is preferably 0.5% by mass or less. When the Si content is 0.5% by mass or less, the corrosion resistance is particularly good. On the other hand, if the Si content exceeds 0.5% by mass, the corrosion resistance may be comparable to that when Si is not contained. A more preferable Si content is less than 0.1% by mass. A more preferable Si content is in the range of 0.01% by mass or more and 0.03% by mass or less.

It should be noted that the Mg--Li alloy of the first embodiment preferably contains two or more elements of the first group from the viewpoint of facilitating the formation of the α-phase. More preferably, all three types are contained. Also, from the same point of view, it is preferable that the content of Ge is the largest among these three types. Also, from the same point of view, it is preferable that the content of Si is the smallest among these three types.

In the first embodiment, the content of Li in the Mg—Li alloy is in the range of more than 11% by mass and 13.5% by mass or less. In the first embodiment, one or more elements selected from the first group and the raw material of the Mg—Li-based alloy having the above Li content are melt-synthesized, and during subsequent cooling, after the molten raw material starts to solidify The cooling rate to 100°C, which is just below the recrystallization temperature, is set to 100°C/min or less. Through such a process, a Mg--Li alloy having an α phase at 25.degree. C. can be obtained. From the viewpoint of facilitating the expression of the α-phase, the cooling rate is more preferably 50° C./min or less, and still more preferably 25° C./min or less. The obtained Mg—Li-based alloy of the first embodiment has an α phase at 25° C. in spite of a relatively large composition range in which the Li content is more than 11% by mass and 13.5% by mass or less. Corrosion can be suppressed more than

The ratio of the α phase in the Mg—Li alloy of the first embodiment at 25°C is preferably 8% or more. When the ratio of the α phase is 8% or more, the corrosion resistance is particularly good. A more preferable α-phase ratio is 20% or more, and a further preferable α-phase ratio is 30% or more.

　The abundance ratio of the α phase can be measured by the X-ray diffraction method. Specifically, for example, it is possible to measure by the following procedure. First, a diffraction pattern is obtained by the 2θ-θ method in the range of 20° to 100° with respect to the Mg--Li alloy, and the background is removed. Next, each peak of the diffraction pattern from which the background has been removed is divided into an α-phase-derived peak and a β-phase-derived peak. Using the cps (Count per Second) value of each diffraction peak, (sum of all cps indicating α phase) / {(sum of all cps indicating α phase) + (sum of all cps indicating β phase)} The abundance ratio of the α phase was calculated from the formula. When identifying each peak of the diffraction pattern as the α-phase-derived peak and the β-phase-derived peak, known powder X-ray diffraction data can be referred to.

The Mg--Li alloy of the first embodiment preferably further contains one or more elements selected from the second group consisting of Al, Zn, Zr, Ca and Be. These elements of the second group are elements that the inventor has confirmed experimentally that even if they exist in the Mg--Li alloy, they hardly inhibit the formation of the α-phase. Here, the sum of the contents of one or more elements selected from the second group is preferably 0.01% by mass or more and 7% by mass or less. When the sum of the contents of the one or more elements selected from the second group is within the above range, at least one of corrosion resistance, fracture strength, ductility and toughness will be good.

The content of Al in the Mg-Li alloy is preferably 5% by mass or less. When the Al content is 5% by mass or less, the breaking strength is good. On the other hand, when the content of Al exceeds 5% by mass, the process window becomes narrow, although the mechanism is unknown, and there is a possibility that the effect of generating the α phase by the elements of the first group is inhibited. A more preferable Al content is in the range of 0.1% by mass or more and 4% by mass or less.

　The content of Zn in the Mg-Li alloy is preferably 2% by mass or less. When the Zn content is 2% by mass or less, good ductility is achieved. On the other hand, if the Zn content exceeds 2% by mass, the process window is narrowed, although the mechanism is unknown, and there is a risk of inhibiting the effect of the first group elements to generate the α phase. A more preferable Zn content is 0.1% by mass or more and 1% by mass or less.

The content of Zr in the Mg-Li alloy is preferably 0.7% by mass or less. When the Zr content is 0.5% by mass or less, the toughness is good. On the other hand, if the Zr content exceeds 0.5% by mass, the toughness may be approximately the same as when Zr is not contained. A more preferable Zr content is in the range of 0.1% by mass and 0.5% by mass or less.

The content of Ca in the Mg-Li alloy is preferably 0.3% by mass or less. When the Ca content is 0.3% by mass or less, good corrosion resistance is achieved. On the other hand, when the content of Ca exceeds 0.3% by mass, the corrosion resistance may become comparable to that when Ca is not contained. A more preferable Ca content is in the range of 0.01% by mass or more and 0.15% by mass or less.

The content of Be in the Mg-Li alloy is preferably 0.1% by mass or less. When the Be content is 0.1% by mass or less, the toughness is good. On the other hand, when the Be content exceeds 0.1% by mass, the toughness may be about the same as when Be is not included. A more preferable Be content is in the range of 0.01% by mass or more and 0.05% by mass or less.

In addition, the Mg—Li alloy of the first embodiment may contain metal elements other than the elements exemplified above within a range in which the characteristics do not change. These metal elements include unavoidable impurities that cannot be avoided during manufacturing. Examples of unavoidable impurities include Fe and Cu. The content of unavoidable impurities in the Mg—Li alloy is 1% by mass or less.

As described above, the Mg--Li alloy of the first embodiment has an α-phase even if the Li content is more than 11% by mass at 25°C, so it is lightweight and excellent in corrosion resistance.

[Manufacturing method of alloy member]
The method for producing a Mg—Li alloy according to the first embodiment includes means for melting and synthesizing raw materials, and then cooling the molten raw materials at a cooling rate of 100° C./min or less from when the molten raw materials begin to solidify to 100° C. It is not particularly limited as long as it has. An example of a preferable manufacturing method is described below.

First, the raw materials for the Mg-Li alloy are prepared (preparation process). Specifically, it contains Mg, Li, and one or more elements selected from the first group consisting of Ge, Mn and Si so as to have a desired composition, and the content of Mg and the content of Li A raw material having a sum of 90% by mass or more is prepared. At this time, the content of Li is more than 11% by mass and 13.5% by mass or less. The purity of the raw material is, for example, 4N, and commercially available high-purity metals can be used. The form of the metal is not particularly limited, and a desired form can be selected from, for example, ingots, chips, flakes, powders, shots and pellets. As for the metal, not only a single metal element but also an alloy composed of a plurality of metal elements may be used. At this time, if necessary, raw materials of one or more elements selected from the second group consisting of Al, Zn, Zr, Ca and Be may be prepared.

Next, these raw materials are heated and melted (heating process). Specifically, these raw materials are placed in a crucible and heated to 600° C. or higher to melt. The temperature should be the melting point or higher of these raw materials, preferably 700° C. or higher. More preferably, it is 800° C. or higher. Although the means for heating is not particularly limited, for example, high-frequency induction heating and electromagnetic induction stirring can be employed. The atmosphere during heating is preferably an inert atmosphere, for example, an argon gas atmosphere, in order to prevent oxidation of the alloy. In addition, the heating rate to the melting temperature is not particularly limited. Also, the temperature may be held for a certain period of time during heating and melting, but the holding time can be appropriately selected depending on the desired shape.

Next, the molten raw material is cooled and solidified (cooling process). Specifically, in the first embodiment, the cooling rate is controlled so that the cooling rate from the start of solidification of the molten raw material to 100° C. just below the recrystallization temperature is 100° C./min or less. The cooling rate described above is the average cooling rate when the molten raw material is cooled to 100° C. just below the recrystallization temperature after starting to solidify. Through the above steps, the Mg—Li alloy of the first embodiment can be obtained.

From the viewpoint of facilitating the expression of the α-phase, a more preferable cooling rate in the cooling step is 50°C/min or less, and a further preferable cooling rate is 25°C/min or less. Moreover, it is preferable to cool at a rate of 100° C./min or less throughout the cooling process from when the molten raw material starts to solidify to 100° C. Also, the cooling rate at 200°C or lower is preferably slower than the cooling rate at temperatures higher than 200°C. When cooling at a speed faster than 100° C./min using rapid cooling means such as gas quenching or water quenching, a β-phase single-phase Mg—Li alloy can be obtained.

In addition, the obtained Mg-Li alloy may be machined to have a desired shape. Machining is appropriately selected from lapping, cutting, barrel polishing, etc., as required. Also, the obtained Mg—Li alloy may be washed. In the cleaning, it is possible to remove metal scraps, dust, oil stains, deteriorated layers, etc. due to machining such as cutting. Therefore, it is possible to use general cleaning methods such as cleaning with an acid or alkali, cleaning using a surfactant, brush cleaning, and ultrasonic cleaning. After washing, drying may be performed as necessary.

Also, the obtained Mg--Li alloy may be used as a base material and a coating may be provided on the base material. The means for providing the coating is not particularly limited, and can be appropriately selected depending on the coating to be provided. If the coating is magnesium fluoride, a known anodizing process or chemical conversion treatment using a known treatment solution can be used. Further, when the film is magnesium phosphate, chemical conversion treatment using a known treatment liquid can be used.

(Second embodiment)
[Alloy material]
The Mg—Li alloy of the second embodiment differs from the first embodiment in the Li content. The Mg—Li alloy of the second embodiment will be described below, focusing on the differences from the first embodiment.

In the second embodiment, the content of Li in the Mg—Li alloy is in the range of 5.34% by mass or more and 11% by mass or less. In the second embodiment, one or more elements selected from the first group and the raw material of the Mg—Li-based alloy having the above Li content are melt synthesized, and during subsequent cooling, the molten raw material starts to solidify to 100 ° C. The cooling rate of is set to 100°C/min or less. Through such a process, it is possible to obtain a Mg--Li alloy with a higher ratio of α-phase at 25° C. than before. From the viewpoint of facilitating the expression of the α-phase, the cooling rate is more preferably 50° C./min or less, and still more preferably 25° C./min or less. The obtained Mg—Li-based alloy of the second embodiment has more α-phase than before in the composition region where the Li content is 5.34% by mass or more and 11% by mass or less, so corrosion can be further suppressed. can.

Here, again, the phase diagram described in the document ““Binary Alloy Phase Diagram”, edited by Seizo Nagasaki and Makoto Hirabayashi, Publisher: Agne Technical Center, ISBN-13: 978-4900041882, Release date: 2001/01 will be explained.

According to this phase diagram, the Li concentration in the equilibrium state at 25° C. is 16.5 atomic % (5 .34% by mass). When the Li content exceeds this concentration relative to Mg, the formation of the β phase begins. In addition, below this concentration, the existence ratio of the α phase in the equilibrium state at 25° C. is 100%.

Next, at the boundary between the eutectic region having both the α phase and the β phase and the single phase region of the β phase (dotted line in the low temperature region), the Li concentration in the equilibrium state at 25 ° C. is 30.0 atomic % (10.9 mass %). When Li is added to Mg at a concentration higher than this concentration, the α-phase disappears and only the β-phase is formed. That is, the existence ratio of the α phase becomes 0% at this concentration or higher.

The intermediate Li concentration between the two Li concentrations read above is 7.96% by mass, and the existence ratio of the α phase in the equilibrium state at 25° C. at this concentration is 50%. When these three Li concentrations and the abundance ratio of the α phase are connected by a three-point approximation curve, the curve can be represented by the following formula (1), where y is the abundance ratio of the α phase and x is the mass% of Li. can.
y=0.3736x ² −24.053x+217.79 (1)

That is, this curve represents the abundance ratio of the α phase in the equilibrium state of Li concentration and 25°C in the conventional Mg-Li alloy.

The Mg—Li-based alloy of the second embodiment is characterized by satisfying the following formula (2), where y is the abundance ratio of the α phase and x is the mass % of Li.
y>0.3736x ² −24.053x+217.79 (2)

Therefore, the Mg—Li-based alloy of the second embodiment has more α-phases than before in the composition region where the Li content is 5.34% by mass or more and 11% by mass or less, so corrosion can be further suppressed. .

[Manufacturing method of alloy member]
The manufacturing method of the Mg—Li alloy member of the second embodiment differs from the first embodiment in the preparation process. A method of manufacturing an Mg--Li alloy member according to the second embodiment will be described below, focusing on the differences from the first embodiment.

The preparation process for preparing the raw material for the Mg-Li alloy will be explained. Specifically, it contains Mg, Li, and one or more elements selected from the first group consisting of Ge, Mn and Si so as to have a desired composition, and the content of Mg and the content of Li A raw material having a sum of 90% by mass or more is prepared. At this time, the content of Li is 5.34% by mass or more and 11% by mass or less. The purity of the raw material is, for example, 4N, and commercially available high-purity metals can be used. The form of the metal is not particularly limited, and a desired form can be selected from, for example, ingots, chips, flakes, powders, shots and pellets. As for the metal, not only a single metal element but also an alloy composed of a plurality of metal elements may be used. At this time, if necessary, raw materials of one or more elements selected from the second group consisting of Al, Zn, Zr, Ca and Be may be prepared.

Next, the cooling process for cooling and solidifying the molten raw material will be explained. Specifically, similarly to the first embodiment, the cooling rate is controlled so that the cooling rate from the start of solidification of the molten raw material to 100° C. is 100° C./min or less. Through the above steps, the Mg—Li alloy of the second embodiment can be obtained.

From the viewpoint of facilitating the expression of the α-phase, a more preferable cooling rate in the cooling step is 50°C/min or less, and a further preferable cooling rate is 25°C/min or less.

(Third embodiment)
[Optical equipment/imaging device]
FIG. 2 shows the configuration of a single-lens reflex digital camera 600, which is an imaging device as an example of the device according to the third embodiment of the present disclosure. In FIG. 2, a camera body 602 and a lens barrel 601, which is an optical device, are combined.

Light from a subject passes through an optical system including a plurality of

lenses

603 and 605, which are examples of components arranged on the optical axis of the imaging optical system in the housing of the lens barrel 601, and is received by the imaging device. It is taken by Here, the lens 605 is supported by an inner cylinder 604 and movably supported with respect to the outer cylinder of the lens barrel 601 for focusing and zooming.

During an observation period before photographing, light from a subject is reflected by a main mirror 607, which is an example of a component inside a housing 621 of the camera body, and after passing through a prism 611, the photographed image is displayed to the photographer through a finder lens 612. be The main mirror 607 is, for example, a half mirror, and light transmitted through the main mirror is reflected by a sub-mirror 608 toward an AF (autofocus) unit 613. This reflected light is used for distance measurement, for example. The main mirror 607 is attached to and supported by a main mirror holder 640 by adhesion or the like. During photographing, the main mirror 607 and the sub-mirror 608 are moved out of the optical path via a drive mechanism (not shown), the shutter 609 is opened, and the photographed light image incident from the lens barrel 601 is formed on the image sensor 610 . Also, the diaphragm 606 is configured to change the brightness and the depth of focus at the time of shooting by changing the aperture area.

The alloy member 100 can be used for at least part of the

housings

620 and 621. The

housings

620 and 621 may be composed only of the Mg—Li alloy member, or the alloy member 100 may be provided with a coating film. Since the Mg—Li alloy of the present disclosure is lightweight and excellent in corrosion resistance, it is possible to provide an imaging device that is lighter in weight and superior in corrosion resistance than conventional imaging devices.

Although the imaging device has been described using a single-lens reflex digital camera as an example, the present disclosure is not limited to this, and may be a smartphone or a compact digital camera.

(Fourth embodiment)
[Electronics]
FIG. 3 shows the configuration of a personal computer, which is an electronic device that is an example of the device according to the fourth embodiment of the present disclosure. In FIG. 3, a personal computer 800 has a display section 801 and a main body section 802 . An electronic component 830, which is an example of a component provided in the housing, is provided inside the housing 820 of the main body 802. As shown in FIG. The alloy member 100 can be used for at least part of the housing 820 of the main body 802 . The housing 820 may be composed only of the Mg—Li alloy member, or the alloy member 100 may be provided with a coating film. Since the Mg—Li alloy of the present disclosure is lightweight and excellent in corrosion resistance, it is possible to provide a personal computer that is lighter in weight and more excellent in corrosion resistance than conventional personal computers.

Although the electronic device has been described using the personal computer 800 as an example, the present disclosure is not limited to this, and may be a smartphone or tablet.

(Fifth embodiment)
[Moving body]
FIG. 4 is a drone, which is an example of a moving object according to the fifth embodiment of the present disclosure. The drone 700 includes a plurality of drive units 701 and a body unit 702 connected to the drive units 701 . A driving circuit (not shown), which is an example of a component, is provided in the main body 702 . The drive unit 701 has, for example, a propeller. As shown in FIG. 4, a leg portion 703 may be connected to the body portion 702, or a configuration in which a camera 704 is connected may be employed. The alloy member 100 can be used for at least a portion of the housing 710 of the body portion 702 and the leg portion 703 . The housing 710 may be composed only of the Mg—Li alloy member, or the alloy member 100 may be provided with a coating film. Since the Mg—Li-based alloy of the present disclosure is excellent in damping properties and corrosion resistance, it is possible to provide drones that are superior in damping properties and corrosion resistance to conventional drones.

Although the drone 700 is used as an example to describe the moving object, the present disclosure is not limited to this, and may be an automobile or an aircraft.

Examples will be described below. First, the evaluation method of the alloy member will be described.

[Evaluation method for alloy members]
(Measurement of α phase abundance ratio)
The abundance ratio of the α phase was measured using an X-ray diffraction method in an environment of 25°C. The X-ray diffractometer used was Ultima IV manufactured by Rigaku. A Cu tube was used as the tube, and the measurement wavelength λ was set to 1.5418 Å. The tube voltage was 40 kV and the tube current was 40 mA. First, a diffraction pattern was obtained by the 2θ-θ method for the range of 2θ of 20° to 100°. The step width was 0.02°, and the scan speed was 2°/min (twice integrated). The background was then removed from the acquired diffraction pattern. Then, each peak of the diffraction pattern from which the background was removed was divided into an α-phase-derived peak and a β-phase-derived peak. Using the cps (Count per Second) value of each diffraction peak, (sum of all cps indicating α phase) / {(sum of all cps indicating α phase) + (sum of all cps indicating β phase)} The abundance ratio of the α phase was calculated from the formula.

For the measurement, a sample was used, which was obtained by cutting the manufactured cylindrical billet of φ60 mm into a plate shape of 20 mm × 50 mm × 2 mm. A surface of 20 mm×50 mm, which is the measurement surface of the sample, was subjected to final polishing of #2000 using a polishing machine and evaluated by the X-ray diffraction method.

(Specific gravity measurement)
The specific gravity was measured by the Archimedes method. Specifically, a cylinder of φ10 mm×10 mm was produced from the produced billet, and the column was immersed in water for measurement. The same sample was measured three times, and the average value was used as the specific gravity value.

(Corrosion resistance measurement)
A plate-shaped sample was prepared by cutting the produced cylindrical billet of φ60 mm in the thickness direction of 15 mm perpendicularly to the length direction. The plate-like sample was left in the atmosphere at 25°C ± 2°C for 3 months. After standing, it was visually observed to confirm whether or not the initial metallic color was maintained. A was given when the metallic color was maintained on the entire surface, B and C were given when at least part of the metallic color was maintained, and D was given when the metallic color could not be maintained.

[Manufacturing and evaluation of alloy members]
(Example 1-1)
First, the composition is Mg-11.5% Li-0.25% Ge-3.4% Al-0.18% Mn-0.04% Be-0.02% Si A metal piece of each element with a purity of 4N was prepared.

Next, these raw materials were placed in an iron crucible. The crucible was heated at a maximum temperature of 800° C. in an argon gas atmosphere to melt the raw material. After being held at 800° C. for 1 hour, it was cooled. Cooling was gradual, and the cooling rate was 15°C/min from 594°C at which solidification started to 100°C. In particular, the cooling rate from 200°C to 100°C was 10°C/min. After cooling was completed, an alloy member of Example 1-1, which was a cylindrical billet with a diameter of 60 mm, was obtained.

Next, samples were prepared from the obtained cylindrical billet for each measurement, and each measurement was performed. As a result, the existence ratio of the α phase in the alloy member of Example 1-1 was 35.4%. Moreover, the specific gravity was 1.43. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained. FIG. 5 is a diagram showing the results of 2θ-θ measurement in Example 1-1.

(Example 1-2)
Example 1-2 differs from Example 1-1 in composition. The composition of Example 1-2 is Mg-12.3% Li-0.29% Ge-2.9% Al-0.09% Mn-0.023% Si-0.15% Ca. Otherwise, the alloy member of Example 1-2 was obtained in the same manner as in Example 1-1.

The abundance ratio of the α phase in the alloy member of Example 1-2 was 22.2%. Moreover, the specific gravity was 1.43. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained.

(Example 1-3)
Example 1-3 differs from Example 1-1 in composition. The composition of Example 1-3 is Mg-11.0% Li-2.2% Al-1.0% Zn-1.1% Mn-0.015% Si. Other than that, an alloy member of Example 1-3 was obtained in the same manner as in Example 1-1.

The abundance ratio of the α phase in the alloy member of Example 1-3 was 30.8%. Moreover, the specific gravity was 1.42. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained.

(Example 1-4)
Example 1-4 differs from Example 1-1 in composition. The composition of Examples 1-4 is Mg-11.9% Li-3.9% Al-1.0% Zn-0.006% Mn-0.01% Si. Otherwise, the alloy member of Example 1-4 was obtained in the same manner as in Example 1-1.

The abundance ratio of the α phase in the alloy member of Example 1-4 was 2.7%. Moreover, the specific gravity was 1.45. Also, in the corrosion resistance measurement, the evaluation was set to C because a change to black was partially confirmed.

(Example 1-5)
Example 1-5 differs from Example 1-1 in composition. The composition of Examples 1-5 is Mg-12.2% Li-3.0% Zn-0.41% Zr-0.01% Si. Otherwise, an alloy member of Example 1-5 was obtained in the same manner as in Example 1-1.

The abundance ratio of the α phase in the alloy member of Example 1-5 was 8.1%. Moreover, the specific gravity was 1.45. Also, in the corrosion resistance measurement, a slight change to black was confirmed, so the evaluation was set to B.

(Example 1-6)
Example 1-6 differs from Example 1-1 in composition. The composition of Examples 1-6 is Mg-13.45% Li-5.54% Al-0.41% Ca-0.3% Mn. Otherwise, an alloy member of Example 1-6 was obtained in the same manner as in Example 1-1.

The abundance ratio of the α phase in the alloy member of Example 1-6 was 3.4%. Moreover, the specific gravity was 1.40. Also, in the corrosion resistance measurement, the evaluation was set to C because a change to black was partially confirmed.

(Example 2-1)
First, each element with a purity of 4N, which is a raw material, so that the composition is Mg-8.9% Li-3.9% Al-0.8% Zn-0.02% Mn-0.19% Si of metal pieces were prepared.

Next, these raw materials were placed in an iron crucible. The crucible was heated at a maximum temperature of 800° C. in an argon gas atmosphere to melt the raw material. After being held at 800° C. for 1 hour, it was cooled. The cooling was slow, and the cooling rate was 20°C/min from 600°C at which solidification started to 100°C just below the recrystallization temperature. In particular, the cooling rate from 200°C to 100°C was set at 15°C/min. After cooling was completed, an alloy member of Example 2-1, which was a cylindrical billet with a diameter of 160 mm, was obtained.

Next, samples were prepared from the obtained cylindrical billet for each measurement, and each measurement was performed. As a result, the existence ratio of the α phase in the alloy member of Example 2-1 was 79.5%. Moreover, the specific gravity was 1.51. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained.

(Example 2-2)
Example 2-2 differs from Example 2-1 in composition. The composition of Example 2-2 is Mg-9.0% Li-4.1% Al-1.1% Zn-0.009% Mn-0.015% Si. Otherwise, an alloy member of Example 2-2 was obtained in the same manner as in Example 2-1.

The abundance ratio of the α phase in the alloy member of Example 2-2 was 47.0%. Moreover, the specific gravity was 1.52. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained.

(Example 2-3)
Example 2-3 differs in composition from Example 2-1. The composition of Example 2-3 is Mg-7.0% Li-6.9% Al-0.8% Zn-0.015% Si. Otherwise, an alloy member of Example 2-3 was obtained in the same manner as in Example 2-1.

The abundance ratio of the α phase in the alloy member of Example 2-3 was 98.7%. Moreover, the specific gravity was 1.60. In addition, in the corrosion resistance measurement, the evaluation was set to A because the metallic color was maintained.

Table 1 shows the above evaluation results. FIG. 6 is a graph showing the Li concentration on the horizontal axis and the abundance ratio of the α phase on the vertical axis in the example.

From Table 1, the alloy members of Examples 1-1 to 1-6, in which the Li content is in the range of more than 11% by mass and 13.5% by mass or less, all have an α phase at 25 ° C. Corrosion resistance was as good as A or B. In particular, Examples 1-1 to 1-3, in which the abundance ratio of the α-phase was 20% or more, had a particularly good corrosion resistance of A. Moreover, the specific gravities of the alloy members of Examples 1-1 to 1-6 were all less than 1.50, and they were particularly lightweight.

Also, the alloy members of Examples 2-1 to 2-3, in which the Li content was in the range of 5.34% by mass or more and 11% by mass or less, had particularly good corrosion resistance of A. In all of the alloy members of Examples 2-1 to 2-3, the ratio of the α phase at 25° C. satisfied the relationship of formula (2) y>0.3736x ² -24.053x+217.79. In addition, the specific gravities of the alloy members of Examples 2-1 to 2-3 were all 1.60 or less, which were higher than those of Examples 1-1 to 1-6, but were light in weight.

As described above, according to the present disclosure, it is possible to provide a Mg-Li alloy member that is resistant to corrosion and that is lightweight.

The present invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the present invention. Accordingly, the following claims are included to publicize the scope of the invention.

This application claims priority based on Japanese Patent Application No. 2021-188734 filed on November 19, 2021, and the entire contents thereof are incorporated herein.

100 alloy member 101 coating 102 base material 600 single-lens reflex digital camera (equipment)
601 lens barrel (equipment)
700 drone (equipment)
800 personal computer (equipment)

Claims

An alloy containing Mg and Li, wherein the sum of the Mg content and the Li content is 90% by mass or more,
The content of Li is in the range of more than 11% by mass and 13.5% by mass or less,
The alloy contains one or more elements selected from the first group consisting of Ge, Mn and Si,
An alloy characterized in that it has an α phase at 25°C.
The alloy according to claim 1, wherein the Ge content is 0.3% by mass or less.
The alloy according to claim 1 or 2, wherein the Mn content is 2% by mass or less.
The alloy according to any one of claims 1 to 3, wherein the Si content is 0.5% by mass or less.
The alloy according to any one of claims 1 to 4, wherein the proportion of α-phase in said alloy at 25°C is 8% or more.
The alloy according to any one of claims 1 to 4, wherein the proportion of α-phase in the alloy at 25°C is 20% or more.
The alloy further contains one or more elements selected from the second group consisting of Al, Zn, Zr, Ca and Be,
7. The alloy according to any one of claims 1 to 6, wherein the sum of the contents of the elements of the second group is 0.01% by mass or more and 7% by mass or less.
The Al content is 5% by mass or less,
The Zn content is 2% by mass or less,
The Zr content is 0.7% by mass or less,
The Ca content is 0.3% by mass or less,
8. The alloy according to claim 7, wherein the Be content is 0.1 mass % or less.
An alloy containing Mg and Li, wherein the sum of the Mg content and the Li content is 90% by mass or more,
Li content of the alloy is in the range of 5.34% by mass or more and 11% by mass or less,
The alloy contains one or more elements selected from the first group consisting of Ge, Mn and Si,
Characterized by satisfying y>0.3736x 2 −24.053x+217.79, where y (%) is the ratio of the α phase of the alloy at a temperature of 25 ° C. and x (mass%) is the content of Li. alloy.
The alloy according to claim 9, wherein the Ge content is 0.3% by mass or less.
The alloy according to claim 9 or 10, wherein the Mn content is 2% by mass or less.
The alloy according to any one of claims 9 to 11, wherein the Si content is 0.5% by mass or less.
The alloy further contains one or more elements selected from the second group consisting of Al, Zn, Zr, Ca and Be,
13. The alloy according to any one of claims 9 to 12, wherein the sum of the contents of the elements of the second group is 0.01 wt% or more and 7 wt% or less.
The Al content is 5% by mass or less,
The Zn content is 2% by mass or less,
The Zr content is 0.7% by mass or less,
The Ca content is 0.3% by mass or less,
14. The alloy according to claim 13, wherein the Be content is 0.1% by mass or less.
An alloy member comprising the alloy according to any one of claims 1 to 14.
a substrate;
and a coating provided on the base material,
An alloy member, wherein the base material comprises the alloy according to any one of claims 1 to 14.
The alloy member according to claim 16, wherein the coating contains magnesium fluoride or magnesium phosphate.
a housing;
and a component provided in the housing,
18. A device, wherein the housing comprises the alloy member according to any one of claims 15-17.
A raw material containing Mg and Li, containing one or more elements selected from the first group consisting of Ge, Mn and Si, and having a sum of the Mg content and the Li content of 90% by mass or more a preparation process to prepare;
A heating step of heating and melting the raw material to 600° C. or higher;
a cooling step of cooling and solidifying the molten raw material,
A method for producing an alloy, wherein in the cooling step, the cooling rate from the start of solidification of the molten raw material to 100°C is 100°C/min or less.
The method for producing an alloy according to claim 19, wherein in the cooling step, the cooling rate from the start of solidification of the molten raw material to 100°C is 50°C/min or less.