JP2000256822A - Surface modified aluminum alloy and surface modifying method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a surface modified aluminum alloy having a surface hardened film of >=HV 500 desired hardness and large thickness and also to provide a surface modifying method for the same. SOLUTION: For example, an Ni-base alloy, having a melting point not lower than the melting point of aluminum and not higher than its boiling point and also having an affinity for nitrogen, is thermally sprayed onto the surface of a base material composed of aluminum alloy. Laser irradiation is applied to the thermally sprayed alloy to form a diffusion alloy layer, and further, nitriding treatment is applied to form nitrogen compounds in the alloy surface and the diffusion alloy layer. By this method, the surface modified aluminum alloy which has an anchor-like diffusion alloy layer in the surface layer of the aluminum alloy and is nitrided to the bottom of the diffusion alloy layer or to its vicinities, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-modified aluminum alloy and a method for modifying the surface, and more particularly to a method for forming a much thicker hardened layer on a surface layer of an aluminum alloy. It is.

[0002]

2. Description of the Related Art Aluminum and aluminum alloy (in the present invention, both are described as "aluminum alloy") are lightweight and have excellent mechanical properties.
Conventionally, it has been widely used industrially as a material for machine structures in various industrial fields. In the automotive industry, in particular, the use of aluminum alloys has been increasing in place of steel materials for the purpose of weight reduction and improved fuel efficiency, and aluminum alloys are inferior in wear resistance and high-temperature strength compared to steel materials. Technological innovations such as higher strength and composites are being actively promoted.

[0003] As a surface modification technique for hardening the surface of an aluminum alloy to improve wear resistance, plating, hard alumite, ion nitriding and the like have hitherto been performed. For example, in the case of a hard plating process, Ni-P plating is applied to the HV for particularly high hardness requirements.
About 500 to 600, it has been reported that further heat-treating the applied with Ni ₃ when the P precipitating HV800 or more hardness is obtained. However, these processes are generally very slow and it is difficult to economically obtain a cured layer of the order of millimeters.

[0004] As a result, the above-mentioned conventional surface modification technology for aluminum alloys does not provide the same surface hardness, diffusion layer depth, wear resistance, and the like as those of the surface hardening treatment of steel materials.
On the other hand, recently, a surface having a relatively thick film surface-hardened layer by melting or melt-alloying the surface using a high energy density heat source such as TIG or MIG welding, an electron beam, or a laser. Reforming technologies are emerging. (1) Surface Modification Using TIG or MIG Welding Method Surface modification by TIG is divided into melting and alloying. The former is used as a local strengthening technique for aluminum alloy castings, which reduces casting defects, refines the structure, and improves the mechanical properties of the fusion zone.

[0005] The latter alloying is carried out by TIG or MIG welding, and is carried out as a surface thick film hardened overlay on the top ring groove of an aluminum piston using an Al-Cu based overlay material. HV 350 is obtained. (2) Surface modification using an electron beam A workpiece is processed in a vacuum using an electron beam device.

This method has already been industrially used mainly for casting alloys, and has the advantage that the surface modification speed is high. There are also a melting treatment method and an alloying method. The former method is applicable to aluminum alloy castings because the structure can be made finer and shrinkage cavities can be removed by the effect of melting and quenching. For the latter, for example, a groove is dug at the top ring position of an aluminum alloy piston, a copper wire is inserted into the groove to create a copper alloyed layer with an electron beam, and then a top ring groove is machined in the alloyed layer. Practical to do. (3) Surface modification using a laser In the case of an electron beam, it is possible to modify in an air, whereas in the case of an electron beam, it is possible to modify in an air. Advantageous over beams. Also in the case of laser, there are a surface melting method and an alloying method. In the former case, when the alloy surface is re-melted and ultra-rapidly solidified, an amorphous phase can be formed.

In the latter alloying method, it is possible to form a hard intermetallic compound by adding an alloying substance or to build up by laser (laser grading), and to use these intermetallic compounds to form an aluminum alloy. The surface can also be modified. As a method for adding the alloying substance, as shown in FIG. 10, a method of coating the base material surface in advance (FIG. 10)
(A)) and a supply method (FIG. 10 (b)) in which a laser beam is directly added to a molten portion during laser irradiation. The coating method is subdivided into a powder / foil coating method, a vapor deposition method, a plating method, a thermal spraying method, and a cladding method. The supply method is subdivided into a powder supply method, a wire supply method, and a gas method.

FIG. 11 shows an example of the result of measurement of the surface hardness of an alloyed layer formed by adding various alloying substances to the surface of an aluminum alloy alone. Cu, M
The hardness of each metal of n, Ni, Co, Fe, Ti, and Cr is HV600 or more due to alloying. On the other hand, a metal having a melting point of the alloying element lower than the melting point of aluminum and higher than the boiling point of aluminum does not form an alloying layer, and has a hardness of HV 200 or less.

[0009]

FIG. 12 shows the relationship between hardness and depth of a hardened layer formed by a surface hardening method of a conventional aluminum alloy (Fukuhisa Matsuda; "Present status of aluminum surface thick film technology"). And Possibilities ”, Light Metal, Vol.40, N
o.10, 1990, reprint). As the hardness of the hardened layer increases, the hardened layer becomes thinner, and as the hardness becomes smaller, the hardened layer becomes thicker. When the aluminum surface is coated with a hard substance by thermal spraying, plating, ion plating or the like (oblique line), a hardness of HV800 or more is obtained, but the thickness of the hardened layer is at most 300 μm, and generally 100 to 100 μm. It stops at about 200 μm. That is, in the related art, a range where the hardness exceeds 500 HV and the thickness of the hardened layer exceeds 300 μm is a blank area at present.

However, recently, in order to form a thick film surface hardened layer having excellent adhesion to a substrate and abrasion resistance on an aluminum alloy, a surface modification method by a combined technique of thermal spraying and laser is newly proposed. (Sadao Kokubo et al., "Surface modification of 6063 aluminum alloy extruded material sprayed with rapidly solidified aluminum alloy powder by Nd-YAG laser", Light Metal, Vol 47, No. 1, 1997, 21-27).

[0011] This is a substrate Al-Mg-Si
For alloy 6063, hard particles of Al-Fe or Al
-A rapidly solidified alloy powder such as Fe-Si is sprayed under an Ar gas atmosphere by a low pressure plasma spraying method, and 1
A thermal spray coating of 100 to 200 μm is formed,
Ar using a 0 W pulsed Nd-YAG laser device
The re-melting process is performed by defocusing the laser beam in a chamber in a gas atmosphere.
Thus, an alloyed layer having excellent adhesion and wear resistance is obtained.

However, when considering the thickness and hardness of the obtained alloy layer, for example, when the alloy powder is Al-50Fe
In the case of (1), the maximum hardness is about HV800 when the thermal spray coating alone is used, but the film thickness is as thin as 100 μm. It has been confirmed that a part of the base material is also melted by performing a remelting treatment with a laser, so that the thickness of the alloy layer is increased to about 250 μm, while the hardness is E = 20J. HV500, E = 3
At 0 J, the HV is 300 to 400, which is reduced by laser irradiation. Also in the case of Al-15Fe-17Si, the sprayed film thickness of 150 μm and the hardness of about HV500, but after laser remelting, the thickness of the alloyed layer becomes 200 to 250 μm, but the hardness decreases to HV250 to 350. ing.

That is, according to the latest method of surface hardening of aluminum alloy by a combined technique of thermal spraying and laser,
Although it is possible to form a relatively thick surface hardened layer with excellent adhesion and abrasion resistance on the surface of the aluminum alloy, a thicker hardened hardened layer with a thickness of the order of millimeters and high hardness can be formed. At present, it has not been obtained.

The present invention has been made in view of such unresolved problems of the prior art, and has an alloying layer having a thickness and hardness that cannot be achieved by the conventional surface modification technology of aluminum alloys. By developing a new aluminum alloy surface modification technology, the surface modification with a target hardness of HV500 or more and a thickness of approximately milli-order has recently been particularly demanded in the fields of automobiles, industrial equipment and aircraft. An object of the present invention is to provide an aluminum alloy and a surface modification method thereof.

[0015]

According to a first aspect of the present invention, there is provided a surface-modified aluminum alloy having an anchor-shaped diffusion alloy layer on a surface of aluminum or an aluminum alloy as a base material. In addition, it is characterized in that the diffusion alloy layer is nitrided to the bottom or its vicinity.

Further, the invention of a method for modifying the surface of an aluminum alloy according to a second aspect of the present invention is to provide a method of modifying the surface of an aluminum alloy, wherein the surface of the aluminum alloy has a melting point not lower than the melting point of aluminum and not higher than the boiling point and has an affinity for nitrogen. A step of spraying an alloy material forming an intermetallic compound, a step of irradiating a laser to the sprayed coating layer formed by the spraying to form a diffusion alloy layer, and further applying a nitriding treatment to the alloy surface and the diffusion layer. And a step of forming a nitride compound.

According to a third aspect of the present invention, in the method for modifying the surface of an aluminum alloy according to the second aspect of the invention, the alloy material is a Ni-based alloy. According to a fourth aspect of the present invention, in the method for modifying a surface of an aluminum alloy according to the second aspect of the invention, the alloy material is a W-based cermet alloy.

According to a fifth aspect of the present invention, there is provided a method for modifying a surface of an aluminum alloy according to the second aspect of the invention, wherein the alloy material is Cr, Si, Mn, Y,
V, Ti, or Fe. According to a sixth aspect of the present invention, in the method for modifying a surface of an aluminum alloy according to any one of the second to fifth aspects, the step of forming the nitrogen compound includes the steps of gas nitrocarburizing, gas nitriding, and ionizing. It is characterized by performing either nitriding or ion nitrocarburizing treatment.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. SUMMARY OF THE INVENTION The inventors of the present invention have developed a surface modification technology for an aluminum alloy that has a thickness and hardness that cannot be achieved by the conventional surface modification technology for an aluminum alloy and that can withstand practical use.
The aim was to obtain a surface-hardened layer having a thickness of about 00 or more and of the order of millimeters. In order to achieve this, it is necessary to add a new method of surface hardening to the surface modification technology of thermal spraying and the formation of a diffusion alloy layer by laser to realize a process of forming a harder and thicker surface hardened layer. We have been conducting diligent research toward its realization.

Normally, plating, nitriding, overlaying, thermal spraying and the like are generally performed as a single technique for the wear-resistant hard surface treatment of an aluminum alloy. In the case of the hard plating treatment, as described above, a hardness of about HV 500 to 600 and a heat treatment of HV 800 or more can be obtained. Difficult to get.

In the nitriding treatment, the molten nitriding by the AC TIG arc, that is, the surface of the aluminum alloy base material is Ar
When the melt congealed by TIG arc -N ₂ mixed gas shielded, but cured layer of HV200~250 is obtained,
Its thickness is about 100 μm. For the overlay,
There is an example in which the wear resistance of an aluminum alloy cast part is partially improved by using a Ni-containing additive by arc welding such as TIG or MIG. In addition, there is a report of a case in which a Fe, Ni, and CrNi additive material on an aluminum alloy base material is melt-alloyed using an electron beam to obtain a hardened layer having a HV of 350 or more and a thickness of 1 mm.

There are many examples of thermal spraying such as spraying WC of an automobile brake disk, Mo spraying a motorcycle engine cylinder, and applying Zo ₂ spraying to an exhaust cone of a jet engine. However, in order to form a thick film, it is necessary to solve problems such as peeling and cracking. The present inventors have found that the formation of a wear-resistant thick-film surface layer of an aluminum alloy, which is difficult with the above various techniques alone, can be increased by combining and combining some of them. The present invention has been accomplished.

That is, in the method for modifying the surface of an aluminum alloy according to the present invention, by using a combination of thermal spraying, laser and nitriding, a surface hardened layer having a hardness of HV 500 or more and a thickness of approximately milli-order is obtained on the aluminum alloy. It is to try. More specifically, first, an alloying substance for forming an intermetallic compound with an aluminum alloy is sprayed on the aluminum alloy base material surface to form a sprayed coating layer on the base material surface. By irradiating this with a laser beam as a high energy density heat source, the sprayed coating layer is remelted to form a diffusion alloy layer made of an intermetallic compound with an aluminum alloy base material. Furthermore, by performing a nitriding treatment to disperse and form a nitride compound on the surface of the aluminum alloy base material and the diffusion alloy layer, the hardness of the surface and the diffusion alloy layer is improved, and a hard and thick wear-resistant thick film surface layer is formed. Is formed.

In the present invention, as an alloying substance used to form an intermetallic compound with the aluminum alloy base material, a metal element having a melting point higher than the melting point of the aluminum alloy and lower than the boiling point and having an affinity for nitrogen, for example, Cr, Si,
Mn, Y, V, Ti, Fe, etc. can be used alone. Alternatively, a Ni-based alloy containing at least one of these metal elements can be used, and specific examples thereof include MA-70 and MA-90.

Also, a tungsten (W) -based cermet alloy containing any of metal elements such as Cr, C, Ni, and Co can be used, and a specific example is SC-43L. Table 1 shows the compositions of these alloys.

[0026]

[Table 1]

As a thermal spraying device for spraying such an alloyed substance onto the surface of an aluminum alloy base material at a predetermined thickness,
For example, various thermal spraying means such as low pressure plasma thermal spraying, arc thermal spraying, flame thermal spraying, high-speed flame thermal spraying (HVOF) self-fluxing alloy thermal spraying, and plasma thermal spraying can be used. FIG. 1 is a schematic view of a low-pressure plasma spraying apparatus, in which a gun (torch) 2 for generating plasma is provided in a closed vessel 1, and an object to be sprayed (a base material made of an aluminum alloy in this case) 3 is provided below the gun 2. Are stored so as to be drivable by the drive system 4 outside the container. The gun 2 is supplied with cooling water 5, plasma gas (Ar, He, etc.) 6, and a thermal spray powder 7 made of a powder of the alloying substance. The inside of the vessel 1 is decompressed to a pressure lower than the atmospheric pressure by the vacuum exhaust system 8, and a high voltage is supplied from the plasma power supply 9 to the anode 2 a and the cathode 2 b of the gun 2, and the plasma jet 10 ejected from the gun 2 is supplied. The thermal spray coating 11 is formed by spraying on the surface of the substrate 3. By appropriately moving the gun 2 and the base material 3, the thermal spray coating 11 can be formed at intervals in a strip shape, or the strip shape can be partially overlapped to cover the entire surface.

As shown in FIG. 2, the thermal spraying alloy layer formed on the surface of the aluminum alloy base material is irradiated with a laser defocus beam having a defocusing distance L set in advance to be re-melted. As a result, a diffusion alloy layer made of an intermetallic compound with an aluminum alloy is formed on the surface layer of the base material. By repeating one-way scanning of the base material surface with the laser defocus beam while moving the base material, a wide range can be irradiated. As the irradiation pattern,
There are continuous patterns that partially overlap each scan, and discontinuous patterns that leave an interval between each scan. One of the patterns may be selected according to the required specifications that differ depending on the type of the product, the application, and the like.

The type of laser is not particularly limited.
O ₂ laser, Ar ion laser, excimer laser, Nd
Commonly used lasers such as -YAG laser, Nd-glass and ruby laser can be used. According to the alloying method using the thermal spraying and the laser beam, the diffusion alloy layer can be formed thick, the alloy composition can be freely changed, and the subsequent nitriding treatment can be performed in a short time and deeply.

Subsequently, a nitriding treatment is performed on the diffusion alloy layer. Gas nitriding, gas nitriding,
Any of gas nitriding, ion nitriding, and ion soft nitriding may be used. By this nitriding treatment, it is possible to obtain a surface hardened layer in which the diffusion alloy layer formed in the anchor layer on the surface layer of the aluminum alloy by the above-described thermal spraying and laser irradiation is deeply nitrided to the bottom or the vicinity thereof.

FIG. 3 is a schematic sectional view of a form of a surface hardened layer formed on a surface layer of an aluminum alloy according to the present invention.
The nitrided layer B is formed deeply to the bottom of or near the anchor-shaped diffusion alloy layer A. This makes it possible to realize a thicker hardened layer that is much harder and thicker than before in the surface layer of the aluminum alloy. 3A shows a case of a continuous pattern, and FIG. 3B shows a case of a discontinuous pattern.

Hereinafter, the effects of the present invention will be specifically described with reference to examples. (Example 1) This is an example in which a surface hardened layer is formed on the surface of a 3 cm square, 2 mm thick aluminum alloy plate (hereinafter referred to as a base material). The composition of the base material is as shown in Table 2. The hardness of the base material is about 30 to 50 HV.

[0033]

[Table 2]

First, using a low-pressure plasma spraying apparatus, the powder of the alloy for spraying is applied to the surface of the base material in an amount of 130 to 150 μm.
m was sprayed. Ni-CrAl based on Ni, well known as MA-90,
Y alloy was used. Plasma spraying equipment; DC40-80KW (Plasma Giken Kogyo Co., Ltd.)
Was used. Thermal spraying conditions are as follows.

Spraying conditions: Current: 750 A Voltage: 43 V Vacuum degree: 50 Torr Spraying distance: 25 cm The hardness of the MA-90 sprayed layer was about 180 to 190 HV.

Next, the surface of the sprayed layer was irradiated with a laser beam in a continuous pattern to perform laser processing, thereby forming a molten alloyed layer (diffusion alloy layer) of the base material and the sprayed alloy. The laser device and irradiation conditions used at this time are as follows. Laser device: MW2000 type YAG laser, maximum output 5.0 kW (normally 2.0 kW (Sumitomo Heavy Industries, Ltd.)
Irradiation conditions: Defocus; 0 to 10 mm Moving speed; 50 cm / min Pitch interval; 1.5 mm Vacuum; 0.4 Torr The hardness of the obtained alloyed layer and the distance (depth) from the surface were measured. The result is shown by a solid line in FIG. 500 from the surface
The hardness at the point of μm was about HV750, but the hardness at depths more rapidly decreased, and the hardness at the depth of 700 μm decreased to HV100 and the hardness at the depth of 750 μm decreased to about HV20. ing.

Thereafter, a gas nitriding treatment was performed at 550 ° C. for 3 hours in a gas nitriding atmosphere based on ammonia gas. The hardness after this nitriding treatment is also indicated by a broken line in FIG. Approximately 4 depths from the surface compared to those before nitriding
At a location of 50 μm, the HV is substantially improved, and at a location of a depth of 700 μm, the HV is substantially improved. FIG. 5 is a photograph (SEM image) showing the metal structure of the surface-modified aluminum alloyed layer (MA-90) after the above “spraying + laser irradiation + nitriding treatment” according to the present invention. , Cr
Is a macrostructure of dendrite (dendritic crystal) formed by solid solution. (B) is an enlarged view of the upper part of the alloyed layer,
It is a Ni-rich dendrite structure (dendritic crystal structure) of Al + Ni + Cr. (C) is an enlarged view of the bottom of the alloyed layer, which is a Cr distribution layer having a high affinity for N.
It can be seen that the hardened layer is formed deeply by the chromium nitride. For this reason, the reason why “spraying + laser treatment + gas nitriding treatment” (dashed line) in FIG. 4 (dashed line) is that the depth of the hardened layer (nitridation layer) is longer than “spraying + laser treatment” (solid line) is as follows.
It can be said that the hardness is increased by the bonding between the Cr distribution layer and N. (Example 2) The surface of an aluminum alloy base material having the composition shown in Table 2 was coated with W
130-based powder of cermet alloy SC-43L
Thermal spraying was performed at a thickness of 150 μm. Thermal spraying conditions are as follows.

Thermal spraying conditions: Current: 755 A Voltage: 56 V Vacuum degree: 500 Torr Thermal spraying distance: 20 cm Next, the surface of the sprayed layer is irradiated with a laser beam in a discontinuous pattern to perform laser processing, and A molten alloyed layer (diffusion alloy layer) with the thermal spray alloy was formed in a discontinuous band shape. The laser device used at this time is the same as in the first embodiment. The irradiation conditions are as follows.

Irradiation conditions: Defocus; 10 mm Moving speed; 100 to 200 cm / min Pitch interval; 2.5 mm Vacuum; 0.3 to 0.5 Torr From the hardness and surface of the alloyed layer obtained at measurement site 1 The result of measuring the distance (depth) is shown by a solid line in FIG.
The measurement place 1 shown in FIG. 6A is a place where the laser beam is irradiated, and is melted into a fine structure to increase the hardness.

Thereafter, a gas nitriding treatment was performed at 550 ° C. for 2 hours in a gas nitriding atmosphere based on ammonia gas. The hardness after this nitriding treatment is also shown in FIG. Its hardness is approximately HV at a depth of 50 μm from the surface.
It improved to about HV2100 at a location of about 2000 and a depth of 70 μm. As a more remarkable effect, by using gas nitriding together, an extremely high degree of alloying layer was obtained from the surface to the deep part. That is, as shown in FIG. 6 (b), the hardness at a depth of 300 μm is only about HV35 by “spraying + laser irradiation” alone, but further subjected to “gas nitriding”. Then HV1500
Approximate hardness was obtained. (Embodiment 3) On the surface of the same aluminum alloy base material as in Embodiments 1 and 2,
r, Si, V powder was sprayed at a thickness of 130 to 150 μm. Thermal spraying conditions are as follows.

Thermal spraying conditions: Current: 750 A Voltage: 43 V Vacuum degree: 50 Torr Spraying distance: 25 cm Next, the surface of this sprayed layer is irradiated with a laser beam so that laser marks do not overlap, and laser processing is performed. Then, a molten alloy layer (diffusion alloy layer) of the base material and the thermal spray alloy was formed. The laser device used at this time is the same as in the first embodiment. The irradiation conditions are as follows.

Irradiation conditions: Defocus; 10 mm Moving speed; 50 cm / min Pitch interval; 2.5 mm Vacuum; 0.3 to 0.5 Torr Hardness of obtained alloyed layer and distance (depth) from surface 7, 8 and 9 are shown by solid lines for each sprayed metal.

FIG. 7 shows that the hardness at a depth of about 500 μm from the surface is H
Although the hardness was about V770, the hardness at a depth higher than that was sharply reduced, and decreased to about HV20 at a depth of about 700 μm. 8, the hardness at a depth of 500 μm from the surface is HV55.
Although it was in the 0th place, the hardness rapidly decreased at a depth greater than that, and when the depth was 550 μm, the HV was 400 and the depth was 700 μm.
In the vicinity of m, the HV is reduced to about 20.

In the case of laser processing after V powder spraying shown in FIG. 9, the hardness was HV65 from the surface to a depth of about 530 μm.
The hardness leveled off at the 0th place, but when the depth was further increased, the hardness rapidly decreased, and the hardness was HV600 at a depth of 550 μm, HV430 at a depth of 600 μm, and about HV20 at a depth of around 700 μm. . The sample subjected to the thermal spraying + laser treatment was thereafter subjected to a gas nitriding treatment at 550 ° C. for 2 hours in a gas nitriding atmosphere based on ammonia gas. The hardness after this nitriding treatment is shown in FIGS.
FIG. 9 also shows a broken line.

In the case of the Cr powder spraying + laser treatment + nitriding treatment shown in FIG.
It is very hard at 0 HV, and then gradually decreases with depth, but the hardness at a depth of about 500 μm is about HV 760, and even at a depth of about 600 μm, the hardness of HV 600 is still maintained. It can be seen that the hardness of the sample increased.

Also, FIG. 8 shows Si powder spraying + laser processing +
In the case of nitriding treatment, the hardness is HV65 at a depth of 500 μm.
It can be seen that the hardness of the HV500 is maintained even at a depth of 550 μm, and the hardness at the same depth is increased by the same nitriding treatment. The V powder spraying + laser treatment + nitriding treatment shown in FIG.
The hardness of around HV800 is maintained up to around μm, and then the hardness sharply decreases as the depth increases. However, even when the depth reaches 800 μm, the hardness Hv500 is still maintained. Notable.

[0047]

As described above, according to the present invention,
Thick film surface hardening with a thickness and hardness that could not be achieved by the conventional aluminum alloy surface modification technology by combining the spraying of the alloying material on the surface of the aluminum alloy, laser beam irradiation and nitriding The effect that the layer can be formed and the application of the aluminum alloy can be greatly expanded is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a thermal spraying apparatus applicable to the present invention;
(A) is a schematic diagram showing a configuration of a main part, and (b) is a configuration diagram of the thermal spray gun.

FIG. 2 is a schematic diagram of laser beam irradiation.

FIG. 3 is a schematic view of a form of an alloyed layer formed on a surface layer of an aluminum alloy according to the present invention.

FIG. 4 is a diagram of one embodiment showing the effect of the present invention.

FIG. 5 is a photograph (SEM image) showing the structure of a surface-modified aluminum alloyed layer according to the present invention, wherein (a) is a macro structure,
(B) is an enlargement of the top of the alloyed layer, and (c) is an enlargement of the bottom of the alloyed layer.

FIGS. 6A and 6B are photographs showing the structure of a surface-modified aluminum alloyed layer, and FIG. 6B is a view showing an effect in another embodiment of the present invention.

FIG. 7 is a diagram of another embodiment showing the effect of the present invention.

FIG. 8 is a diagram of another embodiment showing the effect of the present invention.

FIG. 9 is a diagram of another embodiment showing the effect of the present invention.

FIG. 10 is a diagram illustrating the addition of an alloying substance in a conventional laser alloy method.

FIG. 11 is a diagram comparing the surface hardness of alloyed layers prepared by adding various alloying substances alone.

FIG. 12 is a diagram showing the relationship between the surface hardness and the thickness of the current surface-modified aluminum alloy.

[Explanation of symbols]

 A Diffusion alloy layer B Nitride layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuki Kawada 1-4-3-306 Haruno, Omiya City, Saitama F-term (reference) 4K031 AB08 CB21 CB22 CB24 CB27 CB34 CB39 DA01 DA03 DA04 DA07 FA02 FA05 FA10

Claims (6)

[Claims] 1. A surface-modified aluminum alloy having an anchor-shaped diffusion alloy layer on a surface layer of aluminum or an aluminum alloy as a base material, wherein the diffusion alloy layer is nitrided to the bottom or in the vicinity thereof. . 2. A step of spraying an alloy material having a melting point not lower than the melting point of aluminum and not higher than the boiling point and having an affinity for nitrogen to form an intermetallic compound with the aluminum alloy base material on the surface of the aluminum alloy, Forming a diffusion alloy layer by irradiating the sprayed coating layer formed with the laser with a laser,
Forming a nitride compound on the surface of the alloy and the diffusion alloy layer by performing a nitriding treatment. 3. The method according to claim 2, wherein the alloy material is a Ni-based alloy. 4. The method of claim 2, wherein the alloy material is a W-based cermet alloy. 5. The method according to claim 1, wherein the alloy material is Cr, Si, Mn,
3. The method for modifying the surface of an aluminum alloy according to claim 2, wherein the method is any one of Y, V, Ti, and Fe. 6. The aluminum according to claim 2, wherein in the step of forming the nitrogen compound, one of gas nitrocarburizing, gas nitriding, ion nitriding, and ion nitrocarburizing is performed. Surface modification method for alloys.