JP2020117805A - Alloy coating and method for manufacturing the same - Google Patents

Abstract

To provide an alloy coating consisting of a FeAl intermetallic compound having Cr subjected to solid solution without requiring hot dipping and high temperature and long-time heat treatment when manufactured, and a method for manufacturing the same.SOLUTION: The alloy coating formed on the surface of a base material consists of an intermetallic compound being a FeAl intermetallic compound having Cr subjected to solid solution. The method for manufacturing the alloy coating includes forming the alloy coating consisting of the intermetallic compound being the FeAl intermetallic compound having Cr subjected to solid solution on the surface of a base material, and the alloy coating is formed by forming the FeAl intermetallic compound having Cr subjected to solid solution in the atmosphere, in an inert gas atmosphere or on the base material to solidify the FeAl intermetallic compound on the surface of the base material.SELECTED DRAWING: None

Description

The present invention relates to an alloy film and a method for manufacturing the alloy film.

Conventionally, a method of depositing pure Al, an Al-Si alloy, or the like on the surface of steel as a base material, or diffusing the deposited metal element by heating is known as aluminizing treatment. According to the aluminizing treatment, the aluminum film or the aluminum alloy film is formed on the surface of the steel, so that the characteristics such as corrosion resistance can be improved as compared with the case of the steel alone. Among these, when the high-temperature aluminizing treatment in which the heating is performed at 800° C. or higher is performed, a Fe—Al alloy film having high toughness is formed.

By alloying two kinds of Al and Fe, or three kinds of Al, Cr and Fe, an Fe-Al-based or Fe-Al-Cr-based alloy film is obtained. For example, Patent Document 1 discloses an alloy film made of an FeAl intermetallic compound in which Cr having a Cr content of 10 to 13 atomic% is solid-solved. The alloy film made of the FeAl intermetallic compound in which Cr is solid-dissolved has excellent corrosion resistance against acids, alkalis and salts, and has excellent toughness and wear resistance.

JP2012-201893A

However, since the diffusion process is performed at a high temperature for a long time, it is not practical. For example, in Patent Document 1, after an Al—Cr alloy is hot-dipped on the surface of steel in order to produce an alloy film made of a FeAl intermetallic compound in which a Cr content is 10 to 13 atomic% of Cr, which forms a solid solution with Cr. , These are heated at 1050° C. for 10 hours. Such a diffusion treatment significantly lowers the production capacity in the case of mass-produced products and requires the preparation of a huge furnace for huge members such as bridge piers, which is not practical in any case. Further, hot-dip galvanizing requires preparation of high-temperature molten metal and a bath, which also lacks efficiency and is not practical for a huge member.

The present invention has been made in view of the above problems. It is an object of the present invention to provide an alloy film made of a FeAl intermetallic compound that forms a solid solution of Cr, which does not require hot dipping or heat treatment at high temperature for a long time during manufacturing, and a manufacturing method thereof.

The alloy film according to the first aspect of the present invention is an alloy film formed on the surface of a base material and made of an intermetallic compound, wherein the intermetallic compound is a FeAl intermetallic compound which forms a solid solution with Cr. ..

A method for producing an alloy film according to a second aspect of the present invention is a method for producing an alloy film, which comprises forming an alloy film made of an intermetallic compound on a surface of a base material, wherein the intermetallic compound is solidified with Cr. FeAl intermetallic compound that dissolves, and the alloy film forms an FeAl intermetallic compound that dissolves Cr in the air, in an inert gas atmosphere, or on the substrate and solidifies it on the surface of the substrate. It is formed by

According to the alloy film of the present embodiment, it is possible to provide an alloy film made of a FeAl intermetallic compound that forms a solid solution of Cr, which does not require hot dipping or heat treatment at high temperature for a long time during manufacturing.

According to the method for manufacturing an alloy film according to the present embodiment, an alloy film made of a FeAl intermetallic compound that forms a solid solution of Cr, which does not require hot dipping or heat treatment at high temperature for a long time, can be efficiently manufactured. It is possible to provide various manufacturing methods.

It is an optical photograph of the welding sample obtained in the Example. Sample No. 3 is a graph showing the distribution in the depth direction and the distribution in the depth direction of the atomic% of Al, Cr, and Fe in FIG. Sample No. 2 is a scanning electron micrograph of a cross section taken along the lateral direction of 1 (left-right direction in FIG. 1). It is a figure which shows the base material, a welding bead, and the dimension of a test piece. It is a figure which summarized various analysis results of a bead section. It is a figure which shows the XRD analysis result in the bead layer of a test piece.

Hereinafter, the alloy film according to the embodiment of the present invention and the method for producing the alloy film will be described in detail.

[Alloy film]
The alloy film according to the present embodiment is an alloy film formed on the surface of the base material and made of an intermetallic compound. In addition, the structure provided with the said base material and the alloy film formed on the surface of this base material is an alloy film base material.

(Base material)
The alloy film is formed on the surface of the base material. Examples of the base material include steel and ceramics. When the base material is steel, the alloy coating causes the steel to be surface-treated for rust prevention. When the base material is ceramics, it is metal-coated with an alloy film.

(Alloy film)
The alloy film is made of an intermetallic compound. As the intermetallic compound, an FeAl intermetallic compound that dissolves Cr in solid solution is used. The intermetallic compound is preferably an intermetallic compound containing 37 to 49 atomic% of Al, 10 atomic% or more and less than 13 atomic% of Cr, and the balance being Fe. The intermetallic compound having the above composition is preferable because it has high corrosion resistance and wear resistance. In the intermetallic compound, part of Fe may be replaced with one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti. With respect to the substitution amount of these elements, the total amount (substitution amount) of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti is 0. It is preferably 5 atomic% or less. When a part of Fe in the intermetallic compound is replaced with Ni alone, the substitution amount of Ni is preferably 7.6 atom% or less based on 100 atom% of the intermetallic compound.

The intermetallic compound forming the alloy film preferably contains Al in an amount of 40 to 48 atom %, and more preferably 43 to 47 atom %. When the content of Al in the intermetallic compound is within the above range, the FeAl intermetallic compound content in the alloy film is increased, and the wear resistance is improved, which is preferable.

The intermetallic compound preferably contains Cr in an amount of 10.5 atomic% or more and less than 13 atomic %, more preferably 12 atomic% or more and less than 13 atomic %. When the content of Cr in the intermetallic compound is within the above range, the corrosion resistance of the alloy film is improved, which is preferable.

If the surface of the alloy film is smooth, it does not become a starting point for cracks or stress concentration, which is preferable.

(Effect of alloy film)
The alloy film according to the present embodiment has high wear resistance and corrosion resistance. Due to these properties, the alloy film according to the present embodiment can easily control the alloy composition when the alloy film is manufactured by the method for manufacturing an alloy film described below.

The alloy film according to the present embodiment can be manufactured by, for example, the following method for manufacturing an alloy film.

[Production method of alloy film]
The method for manufacturing the alloy film according to the present embodiment is a method for manufacturing the alloy film according to the present embodiment. Specifically, the method for producing an alloy film according to the present embodiment is a method for producing an alloy film comprising an intermetallic compound on the surface of a substrate, wherein the intermetallic compound is Cr. FeAl is an intermetallic compound that forms a solid solution. The intermetallic compound is preferably an intermetallic compound containing 37 to 49 atomic% of Al, 10 atomic% or more and less than 13 atomic% of Cr, and the balance being Fe. When the intermetallic compound has the above composition, corrosion resistance and wear resistance are improved, which is preferable.

In the method for producing an alloy film according to the present embodiment, the alloy film forms an FeAl intermetallic compound that forms a solid solution of Cr in the air, an inert gas atmosphere, or a base material, and the obtained alloy is used as a base material. It is formed by solidifying on the surface of the material. As a method for solidifying the obtained alloy on the surface of the base material, thermal spraying, sintering, melting, overlay welding, welding or the like is used.

(Spraying)
The thermal spraying is a method of spraying a raw material containing Al, Cr and Fe onto the surface of the base material, and has an advantage that high-speed film formation and large-area operation can be easily performed as compared with plating, physical vapor deposition and the like.

<Substrate>
The base material used for thermal spraying is the same as the base material used for the alloy coating according to the embodiment. Therefore, the description of the base material is omitted.

<raw material>
As a raw material used in the thermal spraying, a raw material containing Al, Cr and Fe is used. As the raw material, for example, a mixed powder containing Cr powder, Fe powder and Al powder is used. It is preferable that this mixed powder contains Cr, Fe, and Al in a compounding amount capable of forming the FeAl intermetallic compound that forms a solid solution with Cr. The mixed powder preferably contains Al in an amount of 37 to 49 atomic% and Cr in an amount of 10 atomic% or more and less than 13 atomic %, with the balance being an amount capable of producing an intermetallic compound of Fe.

The mixed powder may contain powder of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti. For these elements, the total amount of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni, and Ti is 0.5 atomic% or less based on 100 atomic% of the target intermetallic compound. It is preferable that it is contained in an amount. When the mixed powder contains only Ni powder in addition to Al, Cr, and Fe, the Ni powder has a substitution amount of Ni of 7.6 atom% or less with respect to 100 atom% of the target intermetallic compound. It is preferably contained in an amount.

In thermal spraying, Al, Cr, and Fe in the raw material produce a FeAl intermetallic compound in which Cr forms a solid solution during thermal spraying, and the alloy is solidified on the surface of the base material to obtain an alloy film.

Examples of the thermal spraying method include a method using plasma spraying. Plasma spraying is preferable because it is possible to melt and accelerate a material powder having a high melting point, the flight speed of sprayed particles is high, and a good film quality can be obtained. The specific gravity of Al is about half that of Fe and Cr. When spraying a mixed powder of Al powder, Fe powder, and Cr powder as a raw material, the metal powder in the mixed powder is not separated due to vibration of the spraying device, so that uniform mixing is maintained.

(Sintering)
Sintering is a method in which a raw material containing Al, Cr and Fe is used to sinter an FeAl intermetallic compound in which Cr is solid-solved on the surface of a base material, and has a large area compared to hot dipping or high temperature diffusion. It is a construction method that can be easily constructed.

<Substrate>
As the base material used in sintering, the same base material as used in the thermal spraying is used.

<raw material>
As the raw material used for sintering, the same raw material used for the thermal spraying is used. Specifically, as the raw material, for example, a mixed powder containing Cr powder, Fe powder and Al powder is used. It is preferable that this mixed powder contains Cr, Fe, and Al in a compounding amount capable of forming the FeAl intermetallic compound that forms a solid solution with Cr. The mixed powder preferably contains Al in an amount of 37 to 49 atomic% and Cr in an amount of 10 atomic% or more and less than 13 atomic %, with the balance being an amount capable of producing an intermetallic compound of Fe.

The mixed powder may contain powder of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti. For these elements, the total amount of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni, and Ti is 0.5 atomic% or less based on 100 atomic% of the target intermetallic compound. It is preferable that it is contained in an amount. When the mixed powder contains only Ni powder in addition to Al, Cr, and Fe, the Ni powder has a substitution amount of Ni of 7.6 atom% or less with respect to 100 atom% of the target intermetallic compound. It is preferably contained in an amount.

The mixed powder can be sintered by supplying the mixed powder onto a base material, for example, using the same principle as that of a metal 3D printer.

When a metal 3D printer is not used, it is preferable to use a paste obtained by mixing the above-mentioned mixed powder with glycerin as a raw material. When a paste is used as a raw material, the paste can be applied to the base material and then sintered, for example, by laser sintering.

In the sintering, an alloy film is obtained by forming an FeAl intermetallic compound in which Al, Cr and Fe in the raw material dissolve Cr in the sintering and solidifying this alloy on the surface of the base material. ..

As a sintering method, for example, laser sintering is used. Laser sintering is preferable because the power density of the laser can be adjusted in detail.

The specific gravity of Al is about half that of Fe and Cr. When sintering is performed using a mixed powder of Al powder, Fe powder and Cr powder as a raw material, the metal powder in the mixed powder is not separated due to vibration of the sintering device or the like, and is burned so that uniform mixing is maintained. It is preferable to tie it. As a raw material for sintering so that the metal powder in the mixed powder is not separated and the uniform mixing is maintained, it is preferable to use a paste obtained by mixing the mixed powder and glycerin or the like.

That is, it is preferable that the raw material paste containing Al, Cr and Fe is applied to the surface of the base material and then sintered. According to the method of applying this paste and then sintering it, it is possible to prevent the powder from separating during the supply or the machine operation due to the difference in the specific gravity of the powder in the mixed powder.

(Melting)
Melting is a method in which a raw material containing Al, Cr and Fe is used to melt an FeAl intermetallic compound that forms a solid solution of Cr on the surface of a base material. This is an easy construction method.

<Substrate>
As the base material used for melting, the same base material as used for the thermal spraying is used.

<raw material>
As the raw material used for melting, the same raw material used for the thermal spraying is used. Specifically, as the raw material, for example, a mixed powder containing Cr powder, Fe powder and Al powder is used. It is preferable that this mixed powder contains Cr, Fe, and Al in a compounding amount capable of forming the FeAl intermetallic compound that forms a solid solution with Cr. The mixed powder preferably contains Al in an amount of 37 to 49 atomic% and Cr in an amount of 10 atomic% or more and less than 13 atomic %, with the balance being an amount capable of producing an intermetallic compound of Fe.

The mixed powder may contain powder of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti. For these elements, the total amount of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni, and Ti is 0.5 atomic% or less based on 100 atomic% of the target intermetallic compound. It is preferable that it is contained in an amount. When the mixed powder contains only Ni powder in addition to Al, Cr, and Fe, the Ni powder has a substitution amount of Ni of 7.6 atom% or less with respect to 100 atom% of the target intermetallic compound. It is preferably contained in an amount.

The mixed powder can be melted by supplying the mixed powder onto a substrate, for example, using the same principle as that of a metal 3D printer.

When a metal 3D printer is not used, it is preferable to use a paste obtained by mixing the above-mentioned mixed powder with glycerin as a raw material. When a paste is used as a raw material, it can be melted by, for example, laser melting after coating the paste on the base material.

In melting, an alloy film is obtained by forming a FeAl intermetallic compound in which Al, Cr, and Fe in the raw material dissolve in Cr during melting and solidifying this alloy on the surface of the base material.

As a melting method, for example, laser melting is used. Laser melting is preferable because the laser power density can be adjusted in detail.

The specific gravity of Al is about half that of Fe and Cr. When melting using a mixed powder of Al powder, Fe powder and Cr powder as a raw material, the metal powder in the mixed powder should not be separated due to vibration of the melting device, etc., so that uniform mixing is maintained. Is preferred. As a raw material for melting the metal powder in the mixed powder so as not to separate and maintain uniform mixing, it is preferable to use a paste obtained by mixing the mixed powder with glycerin or the like.

That is, it is preferable that the raw material paste containing Al, Cr and Fe is applied to the surface of the base material and then melted. According to the method of applying the paste and then melting the paste, it is possible to prevent the powder from separating during the supply or the machine operation due to the difference in the specific gravity of the powder in the mixed powder.

(Overlay welding)
The overlay welding is a method of overlaying a FeAl intermetallic compound that dissolves Cr in a solid solution on the surface of a base material by using a raw material containing Al, Cr and Fe, and compares it with hot dipping or high temperature diffusion. There is an advantage that large area can be implemented easily.

<Substrate>
As the base material used in the overlay welding, the same base material as that used in the thermal spraying is used.

<raw material>
As the raw material used in the overlay welding, the same raw material used in the thermal spraying is used. Specifically, as the raw material, for example, a mixed powder containing Cr powder, Fe powder and Al powder is used. It is preferable that this mixed powder contains Cr, Fe, and Al in a compounding amount capable of forming the FeAl intermetallic compound that forms a solid solution with Cr. The mixed powder preferably contains Al in an amount of 37 to 49 atomic %, Cr in an amount of 10 atomic% or more and less than 13 atomic %, and the balance being an amount capable of forming an intermetallic compound of Fe.

The mixed powder may contain powder of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni and Ti. For these elements, the total amount of one or more elements selected from the group consisting of Mg, Si, Cu, Mn, Ni, and Ti is 0.5 atomic% or less based on 100 atomic% of the target intermetallic compound. It is preferable that it is contained in an amount. When the mixed powder contains only Ni powder in addition to Al, Cr, and Fe, the Ni powder has a substitution amount of Ni of 7.6 atom% or less with respect to 100 atom% of the target intermetallic compound. It is preferably contained in an amount.

The mixed powder can be overlay welded by, for example, supplying the mixed powder onto a base material.

In addition, when the overlay welding apparatus that supplies the mixed powder onto the base material is not used, it is preferable to use a paste by mixing the mixed powder with glycerin or the like as a raw material. When a paste is used as a raw material, it is possible to carry out overlay welding by, for example, laser overlay welding after applying the paste onto the base material.

In overlay welding, Al, Cr, and Fe in the raw material produce an FeAl intermetallic compound in which Cr forms a solid solution during overlay welding, and the alloy film is solidified by solidifying this alloy on the surface of the base material. can get.

As a method of overlay welding, for example, laser overlay welding is used. Laser overlay welding is preferable because the power density of the laser can be adjusted in detail. As specific conditions for overlay welding, for example, laser power density 93.3 to 103.3 W/mm ² , laser feed speed 0.01 m/s or more, powder supply amount 6.1 to 8.3 g/ s.

The specific gravity of Al is about half that of Fe and Cr. When overlay welding is performed using a mixed powder of Al powder, Fe powder, and Cr powder as a raw material, the metal powder in the mixed powder is not separated due to vibration of the overlay welding device so that uniform mixing is maintained. It is preferable to perform overlay welding. As a raw material for overlay welding so that the metal powder in the mixed powder is not separated and the uniform mixing is maintained, it is preferable to use a paste obtained by mixing the mixed powder and glycerin or the like.

That is, it is preferable that the raw material paste containing Al, Cr and Fe is applied to the surface of the base material and then the overlay welding is performed. According to the method of overlay welding after applying this paste, it is possible to prevent the powder from separating during the supply or the machine operation due to the difference in the specific gravity of the powder in the mixed powder.

(Effects of alloy film manufacturing method)
In the method for manufacturing an alloy film according to the present embodiment, an FeAl intermetallic compound that dissolves Cr in the air, in an inert gas atmosphere, or on a base material is generated, and this alloy is solidified on the surface of the base material. As a result, an alloy film made of an FeAl intermetallic compound that forms a solid solution with Cr is formed. Therefore, according to the method for producing an alloy film according to the present embodiment, there is no need for hot dipping or heat treatment at high temperature for a long time at the time of production. Can be produced.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
A mixed powder of 43 atomic% Fe, 45 atomic% Al, and 12 atomic% Cr was laser overlay welded onto chrome molybdenum steel (SCM440). At this time, the laser power density was changed within the range of 79.5 to 103.3 W/mm ² . Welded samples obtained by changing the laser power density within the above range are shown in FIG. 1-No. Shown as 9. Sample No. No. 1 is a welded sample having a laser power density of 103.3 W/mm ² . Sample No. No. 1 is built up on the surface of chrome molybdenum steel so that the surface of the cross section along the lateral direction (the left-right direction in FIG. 1) is arcuate.

Sample No. For 1, the content of Al, Cr and Fe in the sample was measured using an energy dispersive X-ray analyzer (EDS). The results are shown in Figure 2. 2 shows the sample No. 3 is a graph showing the distribution of the atomic percentages of Al, Cr, and Fe in No. 1 in the depth direction and the distribution of hardness in the depth direction. The horizontal axis represents the depth from the surface of the weld bead. The left vertical axis shows the atomic% of the element of the sample measured by the energy dispersive X-ray analysis (EDS) apparatus. In FIG. 2, the contents of Al, Cr and Fe are shown as ●, □ and Δ plots, respectively. The vertical axis on the right shows the hardness of the sample measured by a micro Vickers hardness meter. In FIG. 2, the hardness of the sample is shown as a ♦ plot.

As shown in FIG. In No. 1, it was found that the hardness of 500 μm from the weld surface of the overlay welded sample was approximately 400 to 500 HV, which was in agreement with the hardness of FeAl that forms a solid solution with Cr. In addition, the sample No. It was found that the ratio of the constituent atoms of 1 was in agreement with the ratio of the constituent atoms of FeAl which solid-solved Cr.

3 shows the sample No. 2 is a scanning electron micrograph of a cross section taken along the lateral direction of 1 (left-right direction in FIG. 1). The arcuate portion on the left side of FIG. 3 is the hardened sample No. 1 shown in FIG. 1 surface. In addition, the broken line shown in FIG. 3 shows the measurement position of the distribution in the depth direction of atomic% of Al, Cr, and Fe shown in FIG.

As shown in FIG. It was found from the left side of FIG. 3 that No. 1 has a three-layer structure of a weld bead layer (first layer), a second layer thermally affected by welding, and a base material (third layer). In addition, it was found that the weld bead layer was FeAl which solid-solved Cr when compared with the result of FIG. In addition, in the case of overlay welding, the first layer is often cracked if the conditions are incorrect. In No. 1, it was found that the first layer was not cracked and a sound film was formed. It is considered that this is because the first layer is made of Fe-rich FeAl(Cr) having excellent toughness based on the result of FIG.

[Example 2]
(Test piece and experimental method)
FIG. 4 is a diagram showing the shape and dimensions of the base material, the weld bead and the test piece. A plate material of 10×50×100 mm shown in the upper left of FIG. 4 is SCM440 steel as a base material. As shown in the upper left of FIG. 4, overlay welding was performed so as to form weld beads on the base metal at 10 mm intervals while changing the laser output density and the powder supply amount. Laser output was fixed at 1.5 kW, feed rate was fixed at 1 cm/s, laser spot diameter was changed from 4.300 to 4.900 mm, powder feed rate was changed to 6.1 and 8.1 g/s, and 9 types were selected. Beads were formed on the base material. The reason for changing the laser spot diameter is to change the laser light intensity per unit area (hereinafter referred to as laser power density).
After forming 9 beads as shown in the upper left of FIG. 4, hardness test of bead cross section, microscope (hereinafter SEM) observation, energy dispersive X-ray analysis (hereinafter, EDS analysis) and X-ray Diffraction (X-ray diffraction: hereinafter XRD) analysis is performed. Therefore, a 4×5×10 mm test piece shown in the lower part of FIG. 4 was cut out from the center of each bead by electrical discharge machining. The test piece shown in the lower part of FIG. 4 was embedded in an epoxy resin in order to use the cross section of the bead shown by the hatching in the lower part of FIG. 4 for various analyses. Then, in order to remove the work-affected layer by electric discharge machining, the surface of the test piece including the hatched portion was sanded by 40 μm, and polished so as to be suitable for various analyses. For the hardness test, a micro Vickers hardness tester was used, and the working load was 0.245 N, the load gradient was 0.04 N/s, and the load holding time was 30 seconds.

(Experimental results and discussion)
<Presence of cracks, hardness test and EDS analysis result>
Of the 9 test pieces, the elemental composition of the bead was close to that of Fe (43 at %):Al (45 at %):Cr (12 at %), laser power density 103.3 W/mm ² , powder supply amount 6.1 g Consider /s.
FIG. 5 is a diagram summarizing various analysis results of the bead cross section. The acquisition position of the SEM image in the test piece is shown in the lower part of FIG. From the SEM image of the bead cross section in the middle part of FIG. 5, it can be seen that the bead is not cracked. The left edge of the image is the bead surface. A dashed line running horizontally through the image indicates that the EDS analysis and hardness test were performed along the line, and the graph at the top of FIG. 4 summarizes them. The left vertical axis represents Vickers hardness, the right vertical axis represents atomic percentages of Fe, Al, and Cr, and the horizontal axis represents depth from the weld bead surface. ◇The plot corresponds to the left vertical axis and shows Vickers hardness. The plots of ●, ■, and ▲ correspond to the right vertical axis and show the atomic percentages of Fe, Al, and Cr, respectively. The hatching in the graph corresponds to the left vertical axis, and is the reference value of the Vickers hardness of the FeAl intermetallic compound (Takao Hachitaka, Tomohiro Sasaki, Shigeaki Kobayashi: Iron and Steel: Vol. 89, No. 11 (2003), 1178-1182). The EDS analysis was performed at intervals of about 100 μm from the bead surface to a depth of 2000 μm. The hardness test was performed at intervals of approximately 25 μm from the bead surface to a depth of 1600 μm.
Since the purpose of this experiment is the surface modification of steel, the surface of the coating will be considered. As shown in FIG. 5, the arithmetic average values of the results of the EDS analysis at a depth of 250 μm from the bead surface were 54 at%, 39 at% and 6.8 at% for Fe, Al and Cr, respectively. The composition was almost close to the initial target of Fe (43 at %):Al (45 at %):Cr (12 at %), and the bead layer was estimated to be an FeAl intermetallic compound containing Cr. On the other hand, almost all of the ◇ plots showing hardness at 250 μm from the surface are within the hatched region of HV _0.245 of 300 to about 640 in FIG. This supports the previous assumption that the bead layer is a FeAl intermetallic compound.

<XRD analysis>
FIG. 6 is a diagram showing an XRD analysis result in the bead layer of the test piece. The Miller index was displayed for each peak by matching with known data (Natl. Bur. Stand. Monogr. 25, 20 (1981), 5). The horizontal axis represents the X-ray diffraction angle, and the vertical axis represents the diffraction intensity. Four peaks are seen in the X-ray diffraction pattern of FIG. The peaks near 2θ=44°, 64°, 81° are those of the FeAl intermetallic compound, respectively. According to the Standard X-ray Diffraction Powder Patterns, which is a data book of X-ray diffraction patterns, the peak of the FeAl intermetallic compound is not limited to this, of course, but the above three peaks are the main peaks with sufficiently strong intensity. The above facts support the above assumption that the bead layer is an FeAl intermetallic compound. Note that the peak near 2θ=79° was ignored because the diffraction peak of the sample holder was detected.
The broken line shown near 2θ=38° is the highest intensity peak obtained when XRD analysis was performed with the powders of Fe and Al mixed at a weight ratio of 1:1 and the mixed powder as it is ( I. Shishkovsky, F. Misssemer, N. Kakovkina and I. Smurov: Crystals, 3 (2013), 517). This peak is a peak due to Al in the mixed powder of Fe and Al (I. Shishkovsky, F. Misssemer, N. Kakovkina and I. Smurov: Crystals, 3 (2013), 517). This peak was not detected at all from the test piece of Example 2. This means that 100% of the Al powder, out of the powders of Fe, Al, and Cr supplied at the time of overlay welding, was entirely used for the production of a certain compound. That is, it means that the percentage of Al element in the bead layer in the graph of FIG. 5 is not that of Al alone, but the Al ratio in some compound. This fact does not deny the previous assumption that the bead layer is an FeAl intermetallic compound.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to these, and various modifications can be made within the scope of the gist of the present invention.

Claims (12)

An alloy film made of an intermetallic compound formed on the surface of a base material,
The alloy film, wherein the intermetallic compound is a FeAl intermetallic compound which forms a solid solution with Cr. The alloy film according to claim 1, wherein the intermetallic compound contains Al in an amount of 37 to 49 atomic %, Cr in an amount of 10 atomic% or more and less than 13 atomic %, and the balance being Fe. The alloy film according to claim 1, wherein the base material is made of steel or ceramics. A method for producing an alloy film, comprising forming an alloy film comprising an intermetallic compound on the surface of a base material,
The intermetallic compound is a FeAl intermetallic compound that forms a solid solution with Cr,
The alloy film is formed by generating an FeAl intermetallic compound that forms a solid solution of Cr in the air, in an inert gas atmosphere, or on the base material, and solidifying the FeAl intermetallic compound on the surface of the base material. A method for producing an alloy film. The method for producing an alloy film according to claim 4, wherein the intermetallic compound contains 37 to 49 atomic% of Al, 10 atomic% or more and less than 13 atomic% of Cr, and the balance is Fe. The said alloy film is formed by spraying the raw material containing Al, Cr, and Fe on the surface of the said base material, The manufacturing method of the alloy film of Claim 4 or 5 characterized by the above-mentioned. The said alloy film is formed by sintering the raw material containing Al, Cr, and Fe on the surface of the said base material, The manufacturing method of the alloy film of Claim 4 or 5 characterized by the above-mentioned. The said alloy film is formed by melting the raw material containing Al, Cr, and Fe on the surface of the said base material, The manufacturing method of the alloy film of Claim 4 or 5 characterized by the above-mentioned. The method for producing an alloy film according to claim 4 or 5, wherein the alloy film is formed by overlay welding a raw material containing Al, Cr and Fe on the surface of the base material. The method for producing an alloy film according to claim 7, wherein the raw material paste containing Al, Cr and Fe is applied to the surface of the base material and then sintered. The method for producing an alloy film according to claim 8, wherein the raw material paste containing Al, Cr and Fe is applied to the surface of the base material and then melted. The method for producing an alloy film according to claim 9, wherein the raw material paste containing Al, Cr, and Fe is applied to the surface of the base material, and then overlay welding is performed.