Alloy member, apparatus, and method for manufacturing alloy member

Abstract

An alloy member includes a base material having magnesium as a main component and containing lithium, and an anti-corrosion film that is provided on the base material and contains magnesium, phosphorus, and fluorine. An average film thickness T of the anti-corrosion film is 20 μm or more, and a difference between a maximum value and a minimum value of a film thickness of the anti-corrosion film is less than 20 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation of International Patent Application No. PCT / JP2024 / 037183, filed Oct. 18, 2024, which claims the benefit of Japanese Patent Application No. 2023-181747, filed Oct. 23, 2023, both of which are hereby incorporated by reference herein in their entirety.BACKGROUNDField of the Technology

[0002] The present disclosure relates to an alloy member, an apparatus, and a method for manufacturing the alloy member.Description of the Related Art

[0003] A magnesium-lithium alloy having magnesium as a main component and containing lithium is lightweight and has excellent mechanical strength, and thus is used in various articles. However, since lithium is an element that is extremely active, is easily ionized, and easily reacts with water, the magnesium-lithium alloy has, for example, a property of being easily corroded under a wet condition. Therefore, there is a need to improve the corrosion resistance of the magnesium-lithium alloy. Japanese Patent Laid-Open No. 2003-171776 discloses subjecting a surface of the magnesium-lithium alloy to chemical conversion treatment using a treatment liquid containing fluorine and aluminum.

[0004] However, since an anti-corrosion film of a magnesium-lithium alloy obtained by the method described in Japanese Patent Laid-Open No. 2003-171776 is manufactured by the chemical conversion treatment, the film thickness of the anti-corrosion film cannot be made sufficiently thick. Therefore, while the appearance is good, it may be corroded when exposed to a high-temperature and high-humidity environment for a long time.SUMMARY

[0005] According to a first aspect for solving the above-described issue, an alloy member includes a base material having magnesium as a main component and containing lithium, and an anti-corrosion film provided on the base material and containing magnesium, phosphorus, and fluorine, wherein an average film thickness T of the anti-corrosion film is 20 μm or more, and wherein a difference between a maximum value and a minimum value of a film thickness of the anti-corrosion film is less than 20 μm.

[0006] According to a second aspect for solving the above-described issue, a method for manufacturing an alloy member includes placing an anode and a cathode in an electrolytic solution, and forming an anti-corrosion film on the anode by applying a voltage between the anode and the cathode, wherein the anode has magnesium as a main component and contains lithium, wherein the electrolytic solution contains fluorine ions, ammonium ions, and phosphate ions, and wherein a concentration of the ammonium ions in the electrolytic solution is in a range of 5.7 mol / L or more and 11 mol / L or less.

[0007] Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic cross-sectional view of an alloy member according to a first embodiment.

[0009] FIG. 2 is a schematic plan view of the alloy member according to the first embodiment.

[0010] FIG. 3 is a schematic plan view of an alloy member according to a comparative example.

[0011] FIG. 4 is a flowchart illustrating steps of manufacturing the alloy member according to the first embodiment.

[0012] FIG. 5 is a schematic diagram of an anodization apparatus for manufacturing the alloy member according to the first embodiment.

[0013] FIG. 6 is a diagram illustrating one embodiment of a current-voltage curve when an anti-corrosion film is formed.

[0014] FIG. 7 is a schematic diagram of an imaging apparatus according to a second embodiment.

[0015] FIG. 8 is a schematic diagram of an electronic apparatus according to a third embodiment.

[0016] FIG. 9 is a schematic diagram of a moving body according to a fourth embodiment.DESCRIPTION OF THE EMBODIMENTSFirst Embodiment[Alloy Member]

[0017] FIG. 1 is a schematic diagram of an alloy member according to a first embodiment, and is a cross-sectional view taken along a stacking direction.

[0018] An alloy member 100 includes a base material 101, and an anti-corrosion film 102 provided on the base material 101. Use application of the alloy member according to the present embodiment is not particularly limited, and can be used as, for example, a structural member such as an exterior member, an interior member, or a sliding member of an apparatus including a part. A coating film such as a primer and an overcoat layer may be provided on the anti-corrosion film 102 in accordance with use application. Examples of the coating film include a heat shielding film having a heat shielding function.(Base Material)

[0019] The base material 101 is made of a magnesium-lithium alloy (hereinafter, Mg—Li alloy) having magnesium as a main component and containing lithium. In this specification, the main component refers to, in a case where a material is composed of a plurality of constituent elements, an element having the largest total mass among the constituent elements. Alternatively, the main component used herein refers to, in a case where a material is composed of a plurality of constituent compounds, a compound having the largest total mass among the constituent compounds.

[0020] Among Mg—Li alloys, a Mg—Li alloy used for the base material 101 preferably has a total content of magnesium and lithium of 90 mass % or more. When the total content of magnesium and lithium is 90 mass % or more, the Mg—Li alloy is lighter than a magnesium alloy not containing lithium. The Mg—Li alloy is a lightweight metal material, and has excellent vibration-damping property and specific strength as compared with the magnesium alloy not containing lithium. Excellent vibration-damping property means that the material quickly converts vibration energy into thermal energy, thereby quickly attenuating vibration. Further, specific strength means tensile strength divided by density, and the higher the specific strength is, the more the member can be reduced in weight.

[0021] The Mg—Li alloy may contain aluminum and / or zirconium in addition to magnesium and lithium, and may further contain germanium and / or beryllium. Further, in addition to the above-described elements, the Mg—Li alloy can further contain at least one element selected from the group consisting of zinc, calcium, silicon, and manganese, and the remainder is inevitable impurities and magnesium. Examples of the inevitable impurities include iron, cobalt, and nickel.

[0022] A content of lithium in the Mg—Li alloy is preferably within a range of 0.5 mass % or more and 15 mass % or less. In a case where the content of lithium is less than 0.5 mass %, the Mg—Li alloy cannot be made lighter than the magnesium alloy, and in a case where the content of lithium is greater than 15 mass %, the vibration-damping property may become insufficient. The content of lithium is preferably within a range of 8 mass % or more and 14 mass % or less. More preferably, the content of lithium is within a range of 5 mass % or more and 11 mass % or less, which is a range where an a phase and a β phase coexist. Within this range, the base material 101 has high corrosion resistance.

[0023] A content of aluminum (Al) in the Mg—Li alloy is preferably within a range of 1 mass % or more and 8 mass % or less. In the alloy according to the present disclosure, Al has a function of enhancing the breaking strength of the alloy. Therefore, when the content of Al is within the above-described range, the alloy according to the present disclosure can have sufficient mechanical strength as compared to when the alloy does not contain Al. It is considered that this is because Al and Mg react to precipitate MgAl2 as a compound thereof, thereby enhancing mechanical strength. The content of Al is more preferably within a range of 4 mass % or more and 7 mass % or less.

[0024] A total content of germanium (Ge) and beryllium (Be) in the Mg—Li alloy is within a range of 0.02 mass % or more and 0.4 mass % or less. In the alloy according to the present disclosure, Ge and Be have a function of enhancing corrosion resistance by partially substituting for Al. As described above, the mechanical strength of the Mg—Li alloy containing Al is enhanced by reaction of Al and Mg; however, at this time, lithium-rich grain boundaries segregate in the matrix phase, thereby making the alloy easily corroded. However, by partially substituting Al with an element smaller in atomic radius than Al, such as Ge and Be, Ge and Be are actively arranged at the grain boundaries in place of Li, and segregation of Li at the grain boundary can be suppressed. This makes it possible to enhance the corrosion resistance. A content of Ge alone is preferably within a range of 0.01 mass % or more and 0.4 mass % or less. The content of Ge alone is more preferably within a range of 0.01 mass % or more and 0.2 mass % or less. A content of Be alone is preferably within a range of 0.02 mass % or more and 0.1 mass % or less. The content of Be alone is more preferably within a range of 0.01 mass % or more and 0.05 mass % or less.

[0025] A content of zirconium (Zr) in the Mg—Li alloy is preferably within a range of 0.6 mass % or more and 3.0 mass % or less. This is because it is possible to prevent a grain size of the base material 101 from coarsening.

[0026] Zinc (Zn), calcium (Ca), silicon (Si), and manganese (Mn) in the Mg—Li alloy can enhance strength of the base material 101. A total content of these elements is preferably within a range of 0.01 mass % or more and 5 mass % or less. A content of Zn is preferably 3 mass % or less. More preferably, the content thereof is 0.2 mass % or more and 3 mass % or less. A content of Mn is preferably 0.3 mass % or less. More preferably, the content thereof is 0.1 mass % or more and 0.3 mass % or less. A content of Si is preferably 0.2 mass % or less. More preferably, the content thereof is 0.1 mass % or more and 0.2 mass % or less. A content of Ca is preferably 1.0 mass % or less. More preferably, the content thereof is 0.1 mass % or more and 1.0 mass % or less.

[0027] Materials of the Mg—Li alloy are not particularly limited. Examples of commercially available materials include LZ91, LAZ771, and Ares manufactured by AmLi Materials Technology Co., Ltd.

[0028] A thickness of the base material 101 is not particularly limited; however, the thickness is preferably greater than a thickness of the anti-corrosion film 102 in terms of sufficient rigidity.(Anti-Corrosion Film)

[0029] The anti-corrosion film 102 is provided on the base material 101. The anti-corrosion film 102 contains magnesium (Mg), phosphorus (P), fluorine (F), and oxygen (O), and preferably contains lithium (Li). An average film thickness T of the anti-corrosion film 102 is 20 μm or more, and therefore, the alloy member 100 according to the present disclosure has excellent corrosion resistance. This makes it possible to prevent water from diffusing and reaching an interface between the anti-corrosion film 102 and the base material 101 over a long period of time. Therefore, even if water permeates from a surface of the anti-corrosion film 102, it is possible to reduce a possibility that the water reaches the base material 101.

[0030] Further, because a difference between a maximum value and a minimum value of a film thickness is less than 20 μm, the alloy member 100 according to the present disclosure has good appearance. More preferably, when the average film thickness Tis within a range of 20 μm or more and less than 45 μm, the difference between the maximum value and the minimum value of the film thickness is less than 15 μm, and more preferably is less than 10 μm. Further, when the average film thickness T is within a range of 45 μm or more and 75 μm or less, the difference between the maximum value and the minimum value of the film thickness is less than 19.5 μm.

[0031] On the other hand, it is considered that the anti-corrosion film obtained by the method described in Japanese Patent Laid-Open No. 2003-171776 has a thickness of about 10 μm at maximum because the anti-corrosion film is manufactured by the chemical conversion treatment. As a result of intensive study by the inventors of the present application, it was found that the anti-corrosion film having the thickness of about 10 μm can withstand a durability test such as a short-time saltwater spray, but it is difficult to suppress corrosion in a high-temperature and high-humidity environment in which, for example, a temperature is 60° C. and a humidity is 85%. This is because, when water adheres to the surface of the Mg—Li alloy, lithium and water react to generate lithium hydroxide (LiOH), and hydrogen gas is further generated. When hydrogen gas is generated, there have been cases where the coating film of the alloy member swells or is peeled. Even when the coating film is not peeled, there have been cases where swelling of the coating film causes an appearance defect.

[0032] Thus, the inventors of the present application found that, when the anti-corrosion film 102 is formed by performing an anodizing treatment under a predetermined condition, the average film thickness T is made thicker and the difference between the maximum value and the minimum value of the film thickness is made less than 20 μm, and thus it is possible to provide an alloy member that has both corrosion resistance and good appearance.

[0033] FIG. 2 is a schematic view of the surface of the alloy member according to the first embodiment. In the anti-corrosion film 102, the difference between the maximum value and the minimum value of the film thickness is less than 20 μm, and the entirety of a surface 1021 can be visually recognized as white. This means that the anti-corrosion film 102 has substantially uniform thickness over the entire surface.

[0034] FIG. 3 is a schematic view of a surface of an alloy member according to a comparative example. In an anti-corrosion film 102X, a difference between a maximum value and a minimum value of a film thickness is 20 μm or more, and a surface 1021X includes a white portion and gray portions 1022A, 1022B, and 1022C that are visually recognized as gray. The gray portions 1022A, 1022B, and 1022C each have a film thickness smaller than that of the white portion, which constitutes the other portion, and are visually recognized as gray because the color of the Mg—Li alloy of the base material is seen through them. Therefore, the surface 1021X of the anti-corrosion film 102X includes the white portion and the gray portions in a mixed state, and thus it cannot be said that the surface 1021X is good in appearance.

[0035] A concentration P1 of phosphorus in a region 102B of the anti-corrosion film 102 up to a thickness of T / 2 on a side close to the base material 101 is preferably lower than a concentration P2 of phosphorus in a region 102A of the anti-corrosion film 102 up to a thickness of T / 2 on a side far from the base material 101. The concentration is an amount of an element per unit area. In the anti-corrosion film 102, it is presumed that phosphorus is present as a magnesium phosphate-based compound. With regard to the base material 101 containing lithium, when a large amount of magnesium phosphate is present in the region 102B including a vicinity of the interface between the base material 101 and the anti-corrosion film 102, oxygen contained in the magnesium phosphate and lithium contained in the base material can react with each other to form lithium oxide (Li2O). The lithium oxide reacts with water, and thus may deteriorate durability of the alloy member under the high-temperature and high-humidity environment.

[0036] A concentration F1 of fluorine in the region 102B of the anti-corrosion film 102 up to the thickness of T / 2 on the side close to the base material 101 is preferably higher than a concentration F2 of fluorine in the region 102A of the anti-corrosion film 102 up to the thickness of T / 2 on the side far from the base material 101. This means that the region 102B has a larger content of inorganic fluoride and a lower content of an inorganic oxide than the region 102A. When a large amount of inorganic oxide is present in the region 102B including the vicinity of the interface between the base material 101 and the anti-corrosion film 102, oxygen and lithium can react with each other to form lithium oxide. Although the type of the inorganic fluoride is not particularly limited, it is preferable that magnesium fluoride (MgF2), in which magnesium and fluorine can stably exist, be present as a main component. When a large amount of magnesium fluoride is present in the region 102B including the vicinity of the interface between the base material 101 and the anti-corrosion film 102, fluorine of the magnesium fluoride and lithium can react with each other to form lithium fluoride (LiF), and the lithium fluoride is stable with respect to water. Accordingly, a possibility of deterioration in durability is low. Therefore, the region 102B is preferably higher in concentration of magnesium fluoride than the region 102A.

[0037] Further, in the anti-corrosion film 102, a content of fluorine is preferably in a range of 9 at % or more and 66 at % or less. Similarly, a content of phosphorus is preferably in a range of 2 at % or more and 26 at % or less. In addition, a content of magnesium is preferably in a range of 14 at % or more and 38 at % or less. This is because film thickness unevenness becomes difficult to be visually recognized. This is for the following reasons. When the content of fluorine is large, the anti-corrosion film 102 good in durability can be obtained. However, because a film growth does not involve dielectric breakdown, film growth in a portion where lithium concentration is relatively low on the surface of the base material may be stopped once a thin film having a high surface resistance is formed. At that time, the film growth continues in other portions where the lithium concentration is relatively high on the surface of the base material, and thus, gradation is caused by a thin film portion and a thick film portion, and may be visually recognized as film unevenness. On the other hand, in a case of a film composition in which the content of fluorine is small, the film composition mainly contains magnesium phosphate. With the film growth with such a composition, the growth includes the dielectric breakdown, and thus the film unevenness is improved; however, the durability may be deteriorated.

[0038] As described above, according to the present disclosure, since the average film thickness T of the anti-corrosion film 102 is 20 μm or more, even when the alloy having magnesium as a main component and containing lithium is used for the base material 101, excellent corrosion resistance is achieved. In addition, since the difference between the maximum value and the minimum value of the film thickness of the anti-corrosion film 102 is less than 20 μm, even when the alloy having magnesium as a main component and containing lithium is used for the base material 101, excellent appearance is achieved. Therefore, according to the present disclosure, it is possible to provide the alloy member 100 that has both the corrosion resistance and the good appearance.[Method for Manufacturing Alloy Member]

[0039] Subsequently, a method for manufacturing the alloy member according to the present disclosure is described with reference to FIGS. 4, 5, and 6. FIG. 4 is a flowchart illustrating steps of manufacturing the alloy member. FIG. 5 is a schematic diagram of an anodization apparatus that performs an anodizing treatment.

[0040] First, an Mg—Li alloy is prepared for an anode. Although not particularly limited, examples of a method for manufacturing the anode include cast molding, thixomolding, and die-cast molding. Such a base material obtained by rapidly cooling molten metal tends to have a surface microstructure different in-plane depending on a molded shape, a direction of the molten metal flow relative to a mold, a temperature difference, and the like. Such in-plane distribution of the surface microstructure may cause variation in thickness of the anti-corrosion film formed. A method described below can provide an alloy member excellent in appearance for such an anode.

[0041] Next, the anode and a cathode are placed in an electrolytic solution. First, an electrolytic solution 401 used for anodization is prepared. The electrolytic solution is a liquid containing fluorine ions, ammonium ions, and phosphate ions. As substances containing fluorine and / or ammonium, ammonium hydrogen fluoride, neutral ammonium fluoride, and ammonia may be used. As substances containing phosphorus, for example, phosphoric acid and triammonium phosphate may be used.

[0042] The electrolytic solution is adjusted such that a concentration of ammonium ions in the solution is in a range of 5.7 mol / L or more and 11 mol / L or less. With the concentration of ammonium ions set within this range, a reaction of the anti-corrosion film can proceed at a lower voltage than when the concentration of ammonium ions deviates from the range. More specifically, because an anti-corrosion film having a low resistance can be formed from an initial growing stage of the anti-corrosion film, it is possible to obtain the anti-corrosion film having a uniform thickness even when the film thickness is increased to 20 μm or more. On the other hand, when the concentration of ammonium ions deviates from the range, a portion having a high resistance is formed from the initial growing stage of the anti-corrosion film, and a potential difference within the film becomes non-uniform. Therefore, it is difficult to increase the film thickness on the portion having the high resistance, and film thickness unevenness occurs, which may cause an appearance defect.

[0043] The electrolytic solution is preferably a solution containing fluorine ions and phosphate ions. A concentration of the fluorine ions is preferably within a range of 2.5 mol / L or more and 10.6 mol / L or less. A concentration of the phosphate ions is preferably within a range of 0.14 mol / L or more and 0.65 mol / L or less.

[0044] An anodization apparatus 400 that forms an anti-corrosion film includes an outer tank 402 that holds the electrolytic solution and adjusts a temperature thereof, and an inner tank 403 in which an energization reaction is performed. A temperature adjustment mechanism 404 is provided in the outer tank 402 and keeps the temperature of the electrolytic solution constant. Note that the solution temperature can be set within a range from a low temperature at which components do not agglomerate to a high temperature at which the components do not decompose. An optimum set temperature is about 25° C., at which a temperature adjustment requires relatively little energy. Further, although the apparatus configuration is described as a two-tank type, the apparatus configuration may also be a one-tank type.

[0045] The outer tank 402 and the inner tank 403 are connected by a magnet pump 405, and the solution circulates therebetween. In forming the anti-corrosion film 102, exchange of the solution at the surface of the Mg—Li alloy is important; however, because the anodization reaction is an exothermic reaction, the electrolytic solution at the surface undergoes natural convection, and thus active solution exchange is performed. Thus, the solution circulation by the pump is performed for removal of byproducts generated in the electrolytic solution rather than for solution exchange at the surface. In anodization at a surface of the Mg—Li alloy, a film is generated, and lithium in an anode is released as ions into the solution. The released lithium ions react with fluorine ions and phosphate ions, which are components of the electrolytic solution, thereby generating sparingly soluble salts. The sparingly soluble salts may remain suspended as fine particles in the solution, thereby causing the electrolytic solution to become cloudy. Accordingly, to remove the fine particles generated in the solution, a bag filter 406 is provided at a solution outlet of the inner tank. The filter is preferably capable of removing fine particles of 10 μm or more. Further, a filter may be provided in a piping system connected to the pump.

[0046] Next, an energization circuit that can form the anti-corrosion film is formed. A carbon electrode 407 that functions as a cathode is placed in the inner tank 403. A cathode material is not particularly limited as long as the cathode material is stable with respect to the electrolytic solution and electrically conductive. For example, platinum, stainless steel, and titanium can be used.

[0047] Next, an anode 408 made of the Mg—Li alloy is set by being clamped in a conductive holding jig 409. A native oxide film is formed on a surface of the anode 408; however, the native oxide film is not required to be removed in advance because the native oxide film is replaced with a fluoride film or a phosphate film in the anodization step. In a case where machining such as cutting is performed on the anode, and oil contamination adheres to the surface of the anode, it is necessary to perform a process such as pre-cleaning to remove the oil contamination on the anode.

[0048] As a material of the conductive holding jig 409, a metal having an anodizing voltage higher than that of the Mg—Li alloy is used. As the conductive holding jig 409, a member independently anodized at a voltage higher than that of the Mg—Li alloy is used. The material may be pure Mg, AZ31, AZ91, or the like, but is not limited thereto.

[0049] The conductive holding jig 409 clamping the anode 408 and a carbon plate are connected to a direct-current stabilized power supply 410 by electric wires such that the conductive holding jig 409 serves as an anode and the carbon plate serves as a cathode. Further, the cathode and the conductive holding jig 409, each connected by the electric wire, are immersed in the inner tank 403 to establish an anodization film formation circuit.

[0050] Then, the anti-corrosion film is formed by applying a voltage between the anode and the cathode.

[0051] FIG. 6 illustrates the current, the voltage, and the temperature of the electrolytic solution during the anodization process. In the graph, a solid line indicates a current value, a dash-dot line indicates a temperature of the electrolytic solution, and a dotted line indicates a voltage value. At a processing time of zero minutes, the conductive holding jig 409 on which the Mg—Li alloy serving as the anode is set is immersed in the inner tank 403. At this time, the anode comes into contact with the solution, a battery is formed, and a minute amount of current is generated. In the energization pattern illustrated in FIG. 6, the current is caused to flow after one minute has elapsed from immersion of the anode in the electrolytic solution; however, no inconvenience occurs even if the current is caused to flow immediately after the immersion.

[0052] Next, the direct-current stabilized power supply 410 is turned on to advance the anodization reaction. The direct-current stabilized power supply to be used has a specification in which a maximum current value is set and a current greater than or equal to the maximum current value does not flow. With regard to a voltage during formation of the anodization film, because an electric resistance on the surface of the Mg—Li alloy is increased with growth of the anti-corrosion film, the voltage is also increased.

[0053] The temperature of the electrolytic solution is kept constant by functioning of the temperature adjustment mechanism 404 that accompanies the apparatus.

[0054] Finally, a timing at which the current is stopped is determined based on an integrated current value flowing through the Mg—Li alloy. By way of example, specifically, an amount of electricity required to grow the anti-corrosion film by 1 μm is 43.5 coulombs per 100 cm2. For example, in a case where an anti-corrosion film of 40 μm is to be formed on an anode made of Mg—Li alloy having a surface area of 100 cm2, a desired film thickness can be obtained by turning off the power supply when energization of 1740 coulombs (43.5×40) is performed.

[0055] Further, a setting value of the current can be determined by a surface area of the anode and a current density. In a case where the current density is small, an anodizing treatment time is long, and accordingly, productivity is impaired. Further, in a case where the current density is high, an anodizing treatment time is shortened and the productivity is improved; however, in a case where the current density is excessively high, the anodization film to be formed may grow while undergoing dielectric breakdown, which may result in reduced durability. Therefore, the current density is preferably from 1 A / 100 cm2 to 10 A / 100 cm2. By the above-described method, the alloy member according to the present disclosure can be obtained.Second Embodiment[Optical Device and Imaging Apparatus]

[0056] FIG. 7 illustrates a configuration of a single-lens reflex digital camera 600 that is an imaging apparatus serving as an example of an apparatus according to a second embodiment of the present disclosure. In FIG. 7, a camera main body 602 and a lens barrel 601 that is an optical device are coupled to each other, and the lens barrel 601 is what is called an interchangeable lens that can be attached to and detached from the camera main body 602.

[0057] Light from an object passes through an optical system including a plurality of lenses 603 and 605 and the like that are examples of parts arranged on an optical axis of an imaging optical system inside a housing 620 of the lens barrel 601 and is received by an imaging element 610, thereby forming an image. The lens 605 is supported by an inner barrel 604 and is movably supported relative to an outer barrel of the lens barrel 601 for focusing and zooming.

[0058] During an observation period before imaging, the light from the object is reflected by a main mirror 607 that is an example of a part inside a housing 621 of the camera main body, passes through a prism 611, then passes through a finder lens 612, and a captured image is displayed to a photographer. The main mirror 607 is, for example, a half mirror, and light that has passed through the main mirror is reflected by a sub-mirror 608 in a direction toward an autofocus (AF) unit 613 and, for example, the reflected light is used for ranging. The main mirror 607 is attached to and supported by a main mirror holder 640 by bonding or the like. During imaging, the main mirror 607 and the sub-mirror 608 are caused to move out of an optical path via a driving mechanism (not illustrated), a shutter 609 is opened, and an optical image of imaging light incident from the lens barrel 601 is formed on the imaging element 610. A diaphragm 606 is configured to be able to change brightness and depth of focus in imaging by changing an aperture area.

[0059] The alloy member 100 can be used for at least a part of the housings 620 and 621. Further, the housing 620 and a housing constituting the camera main body 602 may be composed only of the alloy member according to the present disclosure, or a coating film may be provided on the alloy member. Since the alloy member is excellent in appearance and corrosion resistance, it is possible to provide an imaging apparatus excellent in appearance and corrosion resistance compared to a conventional imaging apparatus.

[0060] Although the imaging apparatus has been described using the single-lens reflex digital camera as an example, the present disclosure is not limited thereto, and the imaging apparatus may be a smartphone or a compact digital camera.Third Embodiment[Electronic Apparatus]

[0061] FIG. 8 illustrates a configuration of a personal computer that is an electronic apparatus serving as an example of an apparatus according to a third embodiment of the present disclosure. In FIG. 8, a personal computer 800 includes a display unit 801 and a main body unit 802. An electronic part 803 that is an example of a part provided in a housing is provided inside a housing 820 of the main body unit 802. The alloy member 100 can be used for at least a part of the housing 820 of the main body unit 802. The housing 820 may be composed only of the alloy member, or a coating film may be provided on the alloy member. Since the alloy member according to the present disclosure is excellent in appearance and corrosion resistance, it is possible to provide a personal computer excellent in appearance and corrosion resistance compared to a conventional personal computer.

[0062] Although the personal computer 800 is described as an example of the electronic apparatus, the present disclosure is not limited thereto, and the electronic apparatus may be a smartphone or a tablet.Fourth Embodiment[Moving Body]

[0063] FIG. 9 illustrates a drone that is a moving body serving as an example of an apparatus according to a fourth embodiment of the present disclosure. A drone 700 includes a plurality of driving units 701 and a main body unit 702 connected to the driving units 701. A driving circuit 705 serving as an example of a part is provided in the main body unit 702. Each of the driving units 701 includes, for example, a propeller. As illustrated in FIG. 9, a leg unit 703 may be connected to the main body unit 702, or a camera 704 may be connected thereto. The alloy member can be used for at least a part of the main body unit 702 and the leg units 703. The main body unit 702 and the leg units 703 may be composed only of the alloy member, or a coating film may be provided on the alloy member. Since the alloy member according to the present disclosure is excellent in appearance and corrosion resistance, it is possible to provide a drone excellent in appearance and corrosion resistance compared to a conventional drone.

[0064] Although the moving body has been described using the drone 700 as an example, the present disclosure is not limited thereto, and the moving body may be an automobile or an aircraft.EXAMPLES

[0065] The present disclosure is more specifically described below by using Examples; however, the present disclosure is not limited by Examples described below. Description is given with reference to FIGS. 4 and 5.<Manufacture of Alloy Member>First Example

[0066] First, the electrolytic solution 401 was prepared by adding pure water to 3680 g of ammonium fluoride and 2280 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution 401 was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved.

[0067] The prepared electrolytic solution was introduced into the outer tank of the anodization apparatus 400 illustrated in FIG. 5, and the magnet pump 405 was started up. After the solution in the inner tank overflowed and circulation of the solution was started, the temperature adjustment mechanism 404 was started up to stabilize the solution temperature at 20° C. Further, a carbon plate functioning as the cathode was immersed and placed in the inner tank and was connected to the cathode of the power supply by a conducting wire.

[0068] As the anode, a die-cast substrate of Ares (composition: Mg-9% Li-4% Al-1% Zn, manufactured by AmLi Materials Technology Co., Ltd.) was prepared. The size thereof is 160 mm×107 mm×2 mm. Die-casting was performed using LMI450M manufactured by Sodic Co., Ltd.

[0069] Next, the conductive holding jig 409 made of AZ31 material was prepared. The conductive holding jig had a fixed hinge at a tip end of a round rod made of AZ31, and had a movable hinge at a position of 107 mm from the fixed hinge. The fixed hinge and the movable hinge were configured to be contracted by an O-ring made of Viton. The conductive holding jig was anodized in advance in the above-described electrolytic solution at a voltage of 140 V until no current flowed. This treatment was performed to facilitate transmission of electric power to the conductive holding jig. A substrate to be anodized was clamped by the conductive holding jig for which the pre-treatment had been completed, was connected to the anode of the power supply with a conducting wire, and was immersed in the inner tank and placed at a position facing the cathode.

[0070] As the direct-current stabilized power supply 410, PAT160-100TMX manufactured by KIKUSUI ELECTRONICS CORPORATION was used. An input current was set to 17.65 A (surface area: 353.1 cm2, current density: 5 A / 100 cm2). The target film thickness was set to 40 μm, and the input amount of electricity was set to 6148 coulombs. The current from the direct-current stabilized power supply was stopped when a designated amount of coulombs was reached.

[0071] The substrate for which the anodizing treatment was completed and the conductive holding jig were removed from the inner tank and were washed with pure water to thoroughly rinse off the electrolytic solution adhering to the surface. Thereafter, the substrate was dried in a clean oven set to 60° C., and thereby the alloy member according to the first example was obtained.Second Example

[0072] An electrolytic solution was prepared by adding pure water to 7820 g of ammonium fluoride and 570 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the current density was set to 1 A / 100 cm2, and an input amount of electricity was set to 4611 coulombs. Except for the above, an alloy member according to a second example was obtained in a manner similar to the first example.Third Example

[0073] An electrolytic solution was prepared by adding pure water to 7360 g of ammonium fluoride and 760 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, an input amount of electricity was set to 9222 coulombs. Except for the above, an alloy member according to a third example was obtained in a manner similar to the first example.Fourth Example

[0074] An electrolytic solution was prepared by adding pure water to 6900 g of ammonium fluoride and 950 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the current density was set to 10 A / 100 cm2, and an input amount of electricity was set to 9222 coulombs. Except for the above, an alloy member according to a fourth example was obtained in a manner similar to the first example.Fifth Example

[0075] An electrolytic solution was prepared by adding pure water to 5060 g of ammonium fluoride and 1710 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the input amount of electricity was set to 11527 coulombs. The base material that was cut out from a casted block material into a shape similar to the shape according to the first example was used. Except for the above, an alloy member according to a fifth example was obtained in a manner similar to the first example.Sixth Example

[0076] An electrolytic solution was prepared by adding pure water to 2760 g of ammonium fluoride and 2660 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the input amount of electricity was set to 7685 coulombs. The base material of the anode was a thixomolded LAZ771 material (composition: Mg-7% Li-7% Al-1% Zn, manufactured by AmLi Materials Technology Co., Ltd.), and one having a shape similar to the shape in the first example was used. Except for the above, an alloy member according to a sixth example was obtained in a manner similar to the first example.First Comparative Example

[0077] An electrolytic solution was prepared by adding pure water only to 9000 g of ammonium fluoride such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride was completely dissolved. Further, the input amount of electricity was set to 9328 coulombs. Except for the above, an alloy member according to a first comparative example was obtained in a manner similar to the first example.Second Comparative Example

[0078] An electrolytic solution was prepared by adding pure water to 8280 g of ammonium fluoride and 380 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the input amount of electricity was set to 12296 coulombs. Except for the above, an alloy member according to a second comparative example was obtained in a manner similar to the first example.Third Comparative Example

[0079] An electrolytic solution was prepared by adding pure water to 1840 g of ammonium fluoride and 3040 g of triammonium phosphate trihydrate such that 20 liters of the electrolytic solution was obtained when the ammonium fluoride and the triammonium phosphate trihydrate were completely dissolved. Further, the input amount of electricity was set to 15370 coulombs. Except for the above, an alloy member according to a third comparative example was obtained in a manner similar to the first example.

[0080] Table 1 summarizes these manufacturing conditions.TABLE 1FirstSecondThirdFirstSecondThirdFourthFifthSixthcomparativecomparativecomparativeexampleexampleexampleexampleexampleexampleexampleexampleexampleAnode (base) materialAresAresAresAresAresLAZ771AresAresAresMolding methodDie-Die-Die-Die-CastingThixo-Die-castDie-castDie-castcastcastcastcastmoldingAmmonium fluoride [g / L]18439136834525313845041492Fluorine ions [mol / L]5.010.69.99.36.83.712.211.22.5Triammonium phosphate11429384886133019152trihydrate [g / L]Phosphate ions [mol / L]0.560.140.190.230.420.650.000.090.75Ammonium ions [mol / L]6.711.010.510.08.15.712.211.54.7Current density [A / 100 cm2]5151055555Amount of electricity [C]614846119222922211527768593281229615370Evaluation(Film Thickness Variation Evaluation Result)

[0081] The film thickness of the anti-corrosion film on the alloy member according to each of the examples and the comparative examples was measured. The film thickness was evaluated using an eddy current-type coating thickness gauge SWT-9000 (probe: NF-0.6) manufactured by SANKO ELECTRONIC LABORATORY CO., LTD. As for the anti-corrosion film having uniform appearance, the film thickness was measured at five unspecified arbitrary positions in a uniform appearance portion, and a difference between a maximum value and a minimum value of measurement values (maximum film thickness difference) was evaluated. As for the first comparative example to the third comparative example in which the appearance included a white portion and gray portions, the film thickness was measured at five positions in the white portion and at five positions in the gray portions, and a difference between a maximum value and a minimum value of measurement values (maximum film thickness difference) was evaluated. Table 2 illustrates results thereof.TABLE 2FirstSecondThirdFirstSecondThirdFourthFifthSixthcomparativecomparativecomparativeexampleexampleexampleexampleexampleexampleexampleexampleexampleAppearance colorWhiteWhiteWhiteWhiteWhiteWhiteWhiteGrayWhiteGrayWhiteGrayportionportionportionportionportionportionportionportionportionportionportionportionFilm thickness (measurement37.026.757.057.965.947.551.76.766.58.349.735.8value) [μm]43.431.467.852.374.048.637.03.857.88.686.932.438.130.161.955.385.258.644.52.946.66.253.335.241.328.450.766.875.442.939.15.967.69.957.928.140.932.464.267.972.354.939.74.867.79.763.226.3Average film thickness [μm]40.129.860.360.073.450.542.44.861.28.562.231.6Maximum film thickness6.45.717.115.619.315.748.861.560.6difference (Max − Min) [μm]

[0082] It was found from the results that the appearance of the anti-corrosion film having the maximum film thickness difference of less than 20 μm was visually recognized as being uniformly white. In contrast, in the comparative examples in which the maximum film thickness difference was 20 μm or more, the appearance was visually recognized as being divided into the white portion and the gray portions, and unevenness was conspicuous. These samples were coated, and appearances of coated surfaces were compared. As a result, the samples of the examples were visually recognized as uniform, whereas, even after coating, the samples of the comparative examples resulted in island-like unevenness in the gray portions being visually recognized as level differences.

[0083] Further, it was found from Table 2 that, in each of the alloy members in which the appearance was visually recognized as being uniformly white, the concentration of ammonium fluoride was in a range of 100 g / L to 400 g / L, and the concentration of triammonium phosphate trihydrate was in a range of 20 g / L to 140 g / L.(EDS Elemental Analysis Result)

[0084] Elemental analysis was performed on the alloy members obtained in the examples and the comparative examples by an EDS (energy dispersive X-ray spectrometer).

[0085] The EDS elemental analysis was performed using a JSM-F100 (FE-SEM) apparatus manufactured by JEOL Ltd. Target elements of the EDS elemental analysis were Mg, P, F, O, C, and Al. As an analysis condition, an acceleration voltage was 13 kV, and a working distance was 9.5 mm to 10 mm.

[0086] Measurement positions were positions 103 indicated by cross marks in FIG. 1, and the anti-corrosion film 102 was divided into seven sections in a film thickness direction, and element composition analysis by the EDS was performed at six points indicated by the cross marks, excluding a point at an interface between the base material and the anti-corrosion film and a point in the vicinity of a surface layer. Then, average values of element ratios at three points on the film side and three points on the surface layer side were evaluated. Table 3 illustrates results thereof.TABLE 3Detected amountDetected amountDetected amountof fluorineof phosphorusof magnesium[at %][at %][at %]F1F2P1P2Mg1Mg2First example35%11%8%25%33%27%Second example60%37%2% 8%25%25%Third example65%18%5%16%24%14%Fourth example66%25%6%20%30%16%Fifth example55%11%7%23%38%26%Sixth example19% 9%24% 26%24%26%First comparative example59%58%0% 0%33%33%Second comparative example57%56%0% 0%34%33%Third comparative example 5% 5%30% 27%25%25%

[0087] In Table 3, the fluorine concentration F1 is the measured concentration in the region 102B, and the fluorine concentration F2 is the measured concentration in the region 102A. The phosphorus concentration P1 is the measured concentration in the region 102B, and the phosphorus concentration P2 is the measured concentration in the region 102A.

[0088] It is found from the results that no appearance unevenness of the anti-corrosion film occurs when the detected amount of fluorine atoms is in a range of 9 at % or more and 66 at % or less, the detected amount of phosphorus atoms is in a range of 2 at % or more and 26 at % or less, and the detected amount Mg of magnesium atoms is in a range of 14 at % or more to 38 at % or less.

[0089] Further, it is confirmed that the detected amount of fluorine has a relationship of F1>F2. Furthermore, it is confirmed that the detected amount of phosphorus has a relationship of P1<P2. Here, it is found that the concentration range of ammonium ions for obtaining a good product is 5.7 mol / L or more and 11 mol / L or less. Note that, even after the samples created in the examples and the comparative examples were left in an environment of 60° C. and 85% relative humidity for 1000 hours after coating, defects such as swelling and peeling of a coating film did not occur.

[0090] As described above, according to the present disclosure, since the average film thickness T of the anti-corrosion film is 20 μm or more, even when the alloy having magnesium as the main component and containing lithium is used for the base material, excellent corrosion resistance is achieved. Further, since the difference between the maximum value and the minimum value of the film thickness of the anti-corrosion film is less than 20 μm, even when the alloy having magnesium as the main component and containing lithium is used for the base material, excellent appearance is achieved. Therefore, according to the present disclosure, it is possible to provide the alloy member that has both corrosion resistance and good appearance.

[0091] It should be noted that the present disclosure is not limited to the embodiments described above, and many modifications can be made within the technical idea of the present disclosure. Further, the effects described in the embodiments merely enumerate the most preferred effects derived from the present disclosure, and the effects of the present disclosure are not limited to those described in the embodiments.

[0092] The present disclosure includes the following.(Item 1)

[0093] An alloy member, comprising:

[0094] a base material having magnesium as a main component and containing lithium; and

[0095] an anti-corrosion film provided on the base material and containing magnesium, phosphorus, and fluorine,

[0096] wherein an average film thickness T of the anti-corrosion film is 20 μm or more, and

[0097] wherein a difference between a maximum value and a minimum value of a film thickness of the anti-corrosion film is less than 20 μm.(Item 2)

[0098] The alloy member according to Item 1, wherein a concentration P1 of the phosphorus in a region of the anti-corrosion film up to a thickness T / 2 on a side close to the base material is lower than a concentration P2 of the phosphorus in a region of the anti-corrosion film up to a thickness T / 2 on a side far from the base material.(Item 3)

[0099] The alloy member according to Item 1 or 2, wherein a concentration F1 of the fluorine in a region of the anti-corrosion film up to a thickness T / 2 on a side close to the base material is higher than a concentration F2 of the fluorine in a region of the anti-corrosion film up to a thickness T / 2 on a side far from the base material.(Item 4)

[0100] The alloy member according to any one of Items 1 to 3, wherein the anti-corrosion film contains an inorganic fluoride.(Item 5)

[0101] The alloy member according to Item 4, wherein a main component of the inorganic fluoride is magnesium fluoride.(Item 6)

[0102] The alloy member according to any one of Items 1 to 5, wherein, in the anti-corrosion film, a content of the magnesium is in a range of 14 at % or more and 38 at % or less, a content of the phosphorus is in a range of 2 at % or more and 26 at % or less, and a content of the fluorine is in a range of 9 at % or more and 66 at % or less.(Item 7)

[0103] The alloy member according to any one of Items 1 to 6, wherein a sum of a content of the magnesium and a content of the lithium in the base material is 90 mass % or more.(Item 8)

[0104] The alloy member according to Item 7, wherein a content of the lithium in the base material is in a range of 0.5 mass % or more and 15 mass % or less.(Item 9)

[0105] The alloy member according to Item 8, wherein the content of the lithium in the base material is in a range of 5 mass % or more and 11 mass % or less.(Item 10)

[0106] The alloy member according to any one of Items 7 to 9,

[0107] wherein the base material contains aluminum, and

[0108] wherein a content of the aluminum in the base material is in a range of 1 mass % or more and 8 mass % or less.(Item 11)

[0109] The alloy member according to any one of Items 7 to 10,

[0110] wherein the base material contains germanium and / or beryllium, and

[0111] wherein a content of the germanium and / or the beryllium in the base material is in a range of 0.02 mass % or more and 0.4 mass % or less.(Item 12)

[0112] The alloy member according to Item 11, wherein, in the base material, the content of the germanium is in a range of 0.04 mass % or more and 0.4 mass % or less, and the content of the beryllium is in a range of 0.02 mass % or more and 0.1 mass % or less.(Item 13)

[0113] The alloy member according to any one of Items 7 to 12,

[0114] wherein the base material contains zirconium, and

[0115] wherein a content of the zirconium in the base material is in a range of 0.6 mass % or more and 3.0 mass % or less.(Item 14)

[0116] The alloy member according to any one of Items 7 to 13,

[0117] wherein the base material contains at least one element selected from the group consisting of zinc, calcium, silicon, and manganese, and

[0118] wherein a sum of contents of element(s) of the group in the base material is in a range of 0.01 mass % or more and 5 mass % or less.(Item 15)

[0119] The alloy member according to Item 14,

[0120] wherein the content of the zinc is 3 mass % or less,

[0121] wherein the content of the calcium is 1 mass % or less,

[0122] wherein the content of the silicon is 0.2 mass % or less,

[0123] wherein the content of the manganese is 0.3 mass % or less, and

[0124] wherein a remainder is inevitable impurities and the magnesium.(Item 16)

[0125] An apparatus, comprising:

[0126] a housing; and

[0127] a part provided inside the housing,

[0128] wherein the housing includes the alloy member according to any one of Items 1 to 15.(Item 17)

[0129] A method for manufacturing an alloy member, the method comprising:

[0130] placing an anode and a cathode in an electrolytic solution; and

[0131] forming an anti-corrosion film on the anode by applying a voltage between the anode and the cathode,

[0132] wherein the anode has magnesium as a main component and contains lithium,

[0133] wherein the electrolytic solution contains fluorine ions, ammonium ions, and phosphate ions, and

[0134] wherein a concentration of the ammonium ions in the electrolytic solution is in a range of 5.7 mol / L or more and 11 mol / L or less.(Item 18)

[0135] The method for manufacturing the alloy member according to Item 17, wherein the electrolytic solution is a solution of ammonium fluoride and triammonium phosphate.(Item 19)

[0136] The method for manufacturing the alloy member according to Item 17 or 18, wherein, in the electrolytic solution, a concentration of the fluorine ions is in a range of 2.5 mol / L or more and 10.6 mol / L or less, and a concentration of the phosphate ions is in a range of 0.14 mol / L or more and 0.65 mol / L or less.

[0137] The present disclosure is not limited to the above embodiments and can be modified and varied in various ways without departing from the spirit and scope of the present disclosure. Accordingly, the following claims are appended to publicly indicate the scope of the present disclosure.

[0138] According to the present disclosure, it is possible to provide an alloy member that has both corrosion resistance and good appearance, and a method for manufacturing the alloy member.

[0139] While the present disclosure has been described with reference to embodiments, it is to be understood that the present disclosure is not limited to the disclosed embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An alloy member, comprising:a base material having magnesium as a main component and containing lithium; andan anti-corrosion film provided on the base material and containing magnesium, phosphorus, and fluorine,wherein an average film thickness T of the anti-corrosion film is 20 μm or more, andwherein a difference between a maximum value and a minimum value of a film thickness of the anti-corrosion film is less than 20 μm.

2. The alloy member according to claim 1, wherein a concentration P1 of the phosphorus in a region of the anti-corrosion film up to a thickness T / 2 on a side close to the base material is lower than a concentration P2 of the phosphorus in a region of the anti-corrosion film up to a thickness T / 2 on a side far from the base material.

3. The alloy member according to claim 1, wherein a concentration F1 of the fluorine in a region of the anti-corrosion film up to a thickness T / 2 on a side close to the base material is higher than a concentration F2 of the fluorine in a region of the anti-corrosion film up to a thickness T / 2 on a side far from the base material.

4. The alloy member according to claim 1, wherein the anti-corrosion film contains an inorganic fluoride.

5. The alloy member according to claim 4, wherein a main component of the inorganic fluoride is magnesium fluoride.

6. The alloy member according to claim 1, wherein, in the anti-corrosion film, a content of the magnesium is in a range of 14 at % or more and 38 at % or less, a content of the phosphorus is in a range of 2 at % or more and 26 at % or less, and a content of the fluorine is in a range of 9 at % or more and 66 at % or less.

7. The alloy member according to claim 1, wherein a sum of a content of the magnesium and a content of the lithium in the base material is 90 mass % or more.

8. The alloy member according to claim 7, wherein a content of the lithium in the base material is in a range of 0.5 mass % or more and 15 mass % or less.

9. The alloy member according to claim 8, wherein the content of the lithium in the base material is in a range of 5 mass % or more and 11 mass % or less.

10. The alloy member according to claim 7,wherein the base material contains aluminum, andwherein a content of the aluminum in the base material is in a range of 1 mass % or more and 8 mass % or less.

11. The alloy member according to claim 7,wherein the base material contains germanium and / or beryllium, andwherein a content of the germanium and / or the beryllium in the base material is in a range of 0.02 mass % or more and 0.4 mass % or less.

12. The alloy member according to claim 11, wherein, in the base material, the content of the germanium is in a range of 0.04 mass % or more and 0.4 mass % or less, and the content of the beryllium is in a range of 0.02 mass % or more and 0.1 mass % or less.

13. The alloy member according to claim 7,wherein the base material contains zirconium, andwherein a content of the zirconium in the base material is in a range of 0.6 mass % or more and 3.0 mass % or less.

14. The alloy member according to claim 7,wherein the base material contains at least one element selected from the group consisting of zinc, calcium, silicon, and manganese, andwherein a sum of contents of element(s) of the group in the base material is in a range of 0.01 mass % or more and 5 mass % or less.

15. The alloy member according to claim 14,wherein the content of the zinc is 3 mass % or less,wherein the content of the calcium is 1 mass % or less,wherein the content of the silicon is 0.2 mass % or less,wherein the content of the manganese is 0.3 mass % or less, andwherein a remainder is inevitable impurities and the magnesium.

16. An apparatus, comprising:a housing; anda part provided inside the housing,wherein the housing includes the alloy member according to claim 1.

17. A method for manufacturing an alloy member, the method comprising:placing an anode and a cathode in an electrolytic solution; andforming an anti-corrosion film on the anode by applying a voltage between the anode and the cathode,wherein the anode has magnesium as a main component and contains lithium,wherein the electrolytic solution contains fluorine ions, ammonium ions, and phosphate ions, andwherein a concentration of the ammonium ions in the electrolytic solution is in a range of 5.7 mol / L or more and 11 mol / L or less.

18. The method for manufacturing the alloy member according to claim 17, wherein the electrolytic solution is a solution of ammonium fluoride and triammonium phosphate.

19. The method for manufacturing the alloy member according to claim 17, wherein, in the electrolytic solution, a concentration of the fluorine ions is in a range of 2.5 mol / L or more and 10.6 mol / L or less, and a concentration of the phosphate ions is in a range of 0.14 mol / L or more and 0.65 mol / L or less.

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