JP5367341B2 - Aluminum alloy casting and method for producing aluminum alloy casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy casting obtained by subjecting an Al-Si-(Al-Si-Mg)-based alloy and an Al-Mg based alloy to compounding which has not been performed heretofore, and to provide a method for producing the same. <P>SOLUTION: The aluminum alloy casting is produced using a die having at least two or more pouring gates. As the die, an ordinary sand die or the like can be used. The respective pouring gates are made to communicate with the parts in the die corresponding to product parts requiring different characteristics directly by runners. Further, the cavity in the die is an integrated space, and there is no fact that cavities communicating with the respective pouring gates are divided by a partition or the like. In almost the same distance from the respective pouring gates, a joined part is formed. The joined part is the one at which molten metals poured from the respective pouring gates are joined. The molten metals of AC4CH and AC7A are simultaneously made to flow into the respective pouring gates of the die. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a casting made of a dissimilar aluminum alloy such as an Al—Si (Al—Si—Mg) based alloy containing Si and an Al—Mg based alloy containing a large amount of Mg, and a method for producing the same.

  Aluminum alloys have excellent properties such as lightness, heat and electrical conductivity, and workability, and are used in various fields. Aluminum alloys have different properties (depending on the alloy system) depending on their additive elements, and are selectively used depending on the application.

  In particular, depending on the required wear resistance, heat resistance, strength characteristics, etc., methods such as partial compounding of only necessary parts with other materials such as steel materials or combining aluminum alloy parts with different characteristics are adopted. It has been. Such conventional dissimilar metal (alloy) compounding is generally performed by mechanical joining using screws or the like, or solid-liquid joining by casting. Casting casts give the necessary properties to only a part of the product, and the product can be combined in one process.

  As a method of compounding by cast-in, for example, there is an aluminum integrated caliper body manufactured by casting an aluminum pipe of 1000 series, 3000 series, 6000 series or the like with an aluminum cast alloy (Patent Document 1).

JP 2000-220667 A

  However, the method using cast-in between aluminum alloys as in Patent Document 1 may cause melting of the cast-in aluminum member unless the pouring temperature and solidification time of the aluminum alloy to be poured are strictly limited. Furthermore, depending on the type of aluminum alloy, a large amount of intermetallic compounds that adversely affect the mechanical strength may be deposited at the boundary portion, and sufficient bonding strength may not be obtained.

  For example, Al—Si (Al—Si—Mg) -based alloys are alloys having high strength and castability, and many aluminum casting alloys contain a large amount of Si. On the other hand, the Al—Mg-based alloy is an alloy containing a large amount of Mg and has high toughness as a non-heat-treatable alloy.

When an alloy containing a large amount of Si and a metal containing a large amount of Mg are combined by a conventional method, a large amount of Mg ₂ Si intermetallic compound precipitates at the boundary. When a large amount (roughly) of an intermetallic compound is produced, particularly mechanical properties are significantly deteriorated. For this reason, in the conventional construction method using cast-in, for example, an Al—Mg-based alloy is avoided as the cast-in aluminum alloy. However, depending on the product, there has been a demand to utilize the high toughness of Al-Mg alloys.

  In particular, since an aluminum alloy casting is not subjected to cold working or the like after casting, it needs to be surely integrated during casting. That is, if an abrupt characteristic change occurs between aluminum alloys having different characteristics, there is a risk of breaking during use.

  The present invention has been made in view of such problems, and an aluminum alloy casting in which an Al—Si (Al—Si—Mg) based alloy and an Al—Mg based alloy which have not been conventionally used are combined and the production thereof. It aims to provide a method.

In order to achieve the above-mentioned object, the first invention is a first alloy part and a second alloy part that is integrated with the first alloy part and has a different composition from the first alloy part. And the size of the α phase and the eutectic at the boundary between the first alloy part and the second alloy part is continuously changed from a homogeneous structure in each alloy part , and the boundary In the part, from the first alloy part to the second alloy part, the concentration of Mg continuously increases, the concentration of Si decreases continuously, and the first alloy part is a JIS-AC4C alloy. And the second alloy part is a JIS-AC7A alloy, and an intermetallic compound is precipitated at the boundary part, and the amount of precipitation of the intermetallic compound at the boundary part is determined by the first alloy part. And the second alloy portion continuously changing, and the width of the boundary portion is 400 μm or less. , And the said intermetallic compound is an aluminum alloy casting, which is a Mg 2 _Si.

  Here, the boundary portion is located between the alloy portions having a homogeneous component and structure, and refers to a portion having a component and structure different from the homogeneous component and structure in each alloy portion.

Na us, amount of precipitation of intermetallic compounds, and continuously changes toward between the first alloy portion and the second alloy portion, smooth precipitation amount by intermetallic compound is dispersed throughout the boundary It means that there is no peak of the precipitation amount of the intermetallic compound at the interface between the first alloy part and the second alloy part.

  According to the first invention, an AC4C alloy containing a large amount of Si and having a high strength is integrated with an AC7A alloy containing a large amount of Mg and having a high toughness. Since the Si concentration changes continuously, the intermetallic compound does not concentrate and precipitate at the boundary. For this reason, strength deterioration of the boundary portion is suppressed.

  In particular, the combination of AC4C having a high strength and AC7A having a high toughness is suitable for a part or the like that partially requires strength or toughness.

  If the amount of precipitation of the intermetallic compound at the boundary is between the amount of precipitation of the intermetallic compound in the AC4C and AC7A alloy and the width of the boundary is 400 μm or more, the structure of the boundary is inclined, This is desirable because the mechanical properties do not change rapidly.

  ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy casting which compounded the Al-Si (Al-Si-Mg) type alloy and Al-Mg type alloy which were not performed conventionally, and this manufacturing method can be provided.

  Hereinafter, an aluminum alloy casting according to an embodiment of the present invention will be described. The aluminum alloy casting according to the present embodiment is obtained by integrating a JIS-AC4C alloy (hereinafter simply referred to as AC4C) and a JIS-AC7A alloy (hereinafter simply referred to as AC7A).

  AC4C is an alloy of Al—Si (which may be classified as Al—Si—Mg, but referred to herein as Al—Si), and contains a large amount of Si in order to improve castability. A small amount of Mg is added to form an intermetallic compound with Si and obtain an aging effect by heat treatment.

On the other hand, AC7A is a non-heat treatment type Al—Mg alloy and has high toughness. As described above, Mg forms an intermetallic compound of Mg ₂ Si by reaction with Si, and precipitates in the aluminum matrix at a high temperature such as heat treatment.

  Therefore, when a high Si Al-Si alloy and a high Mg Al-Mg alloy are integrated by casting at a high temperature, a large amount of coarse intermetallic compounds are precipitated at the boundary, and mechanical The properties are significantly reduced. For example, when one alloy is cast with the other alloy, a high Mg or high Si region is formed on the surface of the boundary portion (solid side) by diffusion in the solid, where an intermetallic compound is formed. This is because the precipitation of is promoted. For this reason, conventionally, integrating an Al—Si based alloy and an Al—Mg based alloy in one step has not been performed.

  On the other hand, the inventors have confirmed that the above-mentioned high Mg and high Si regions are not formed in the vicinity of the boundary between AC4C and AC7A by integrating AC4C and AC7A in direct contact in the molten state. I found it.

  That is, between AC4C, which is high Si, and AC7A, which is low Si, Si changes continuously, and there is no rapid concentration change or peak. Similarly, between AC4C, which is low Mg, and AC7A, which is high Mg, Mg changes continuously, and there is no sudden concentration change or peak. That is, the alloy element concentration is inclined at the boundary between AC4C and AC7A. This is because there is no other member such as a partition between the two alloys, and by bringing the molten alloys into direct contact with each other, the solidification of both alloys proceeds almost simultaneously, and each element diffuses between the two alloys. This is because they are mixed by convection.

  At the boundary between the two alloys, each element changes continuously with an inclination. For this reason, the metal structure (for example, the size of the α phase, the area ratio, the size and distribution of the eutectic, the amount of intermetallic compound produced, etc.) in the boundary portion changes continuously. Further, local intermetallic compound precipitation does not occur. Therefore, the mechanical properties do not change abruptly at the boundary between the two alloys accompanying the metal structure. Therefore, the boundary part of both alloys does not break preferentially.

  Note that the width of the boundary is preferably 400 μm or more. If the width of the boundary portion is smaller than 400 μm, even if the component or tissue continuously changes in the boundary portion, the change inclination angle becomes too large, and the change becomes abrupt.

  Next, the manufacturing method of the aluminum alloy casting concerning this invention is demonstrated. The aluminum alloy casting according to the present invention is manufactured using a mold having at least two gates.

  As the mold, a normal sand mold, mold, graphite mold or the like can be used. Each gate is communicated with a portion in a mold corresponding to a product portion where it is desired to obtain different characteristics through a runner. The cavities in the mold are an integral space, and the cavities communicating from the respective gates are not separated by a partition wall or the like.

  A junction is formed at approximately the same distance from each gate. The joining part is a part where the molten metals poured from the gates join each other. In addition, the arbitrary position in a casting_mold | template can also be set as a merge part by controlling the magnitude | size of a runner and the amount of pouring. Also, from the viewpoint of internal quality, it is desirable to set gas venting or the like at the junction so as not to cause defects such as a hot water boundary. Alternatively, the molten metal may not collide with the joining portion from the front, but may join at a certain angle so that no hot water pool or the like is formed.

  The molten metal of AC4C and AC7A is poured simultaneously into each gate of the mold. The pouring temperature is desirably 20 ° C to 100 ° C higher than the liquidus of each alloy. If the pouring temperature is less than the liquidus + 20 ° C. and the pouring temperature is too low, the hot water flow in the mold may be deteriorated and defects may occur, which is not desirable. Moreover, since the pouring temperature is low and the hot water flow is deteriorated, the position of the joining portion may be changed, which is not desirable.

  Further, if the pouring temperature is too high, ie, the liquidus + 100 ° C. or more, it is not desirable because it may cause oxidation of the molten metal or cause the product to close. Accordingly, the pouring temperature is desirably 20 ° C. to 100 ° C. of the liquidus of each alloy.

  Since the liquidus temperature of AC4C is about 615 ° C. and the liquidus temperature of AC7A is about 635 ° C., the temperature of the molten metal poured from the gate may be different for each alloy.

  The manufactured aluminum alloy casting is then taken out of the mold and cooled by a normal method. Thereafter, heat treatment can be performed as necessary.

  As an aluminum alloy casting manufactured in this way, AC7A can be used for a portion that cannot be broken when a force is applied, and AC4C can be used for a portion where other strength is desired. For example, the present invention can be applied to a hammer, a golf club, or the like whose head is AC4C and whose grip is AC7A. The present invention can also be applied to a steering hole in which the wheel portion is made of AC7A and the boss portion is made of AC4C, or a bearing member in which the bearing portion is made of AC7A and the main body portion is made of AC4C.

  As described above, according to the aluminum alloy casting according to the present invention, AC4C is applied to a portion where particularly high strength is required, and AC7A is applied to a portion where high toughness is required. An aluminum alloy casting with can be produced in one step. For this reason, a manufacturing process can be simplified. In particular, it is not necessary to strictly control the pouring temperature, the solidification time, and the like, unlike the casting of different Al alloys.

  In addition, since the composition, the structure, and the like continuously change at the joining portion of both alloys and there is no abrupt change point, the formation of intermetallic compounds is suppressed. Further, since the mechanical properties at the junction are continuous, the breakage at the boundary of the dissimilar alloy is suppressed.

  In this embodiment, an example in which AC4C and AC7A are integrated has been shown. However, an alloy such as AC4CH can be used instead of AC4C, and other Al—Si alloys and Al—Mg alloys can be used. Can be integrated in a similar manner. Moreover, it can also integrate by the same method using 3 or more types of alloys.

  The aluminum alloy casting according to the present invention was manufactured, and the structure and strength were investigated. FIG. 1 is a view showing a mold 1 for producing an aluminum alloy casting according to the present invention. FIG. 1 (a) is a plan view, and FIG. 1 (b) is a cross-sectional view taken along line AA in FIG. FIG. 1B is a cross-sectional view taken along the line BB in FIG.

  The mold 1 has two gates 3a and 3b. The gates 3 a and 3 b are connected to each other in the mold 1. The part located at substantially the same distance from the gates 3a, 3b is the joining part 5. When molten metal is poured from the gates 3a and 3b, the molten metal flows from the gate to the cavity in the mold and flows toward the end of the mold 1 on the side opposite to the gate. The cab tee of the mold 1 is substantially flat and has a length of about 150 mm.

  The mold used was a graphite mold and preheated to about 250 ° C. Further, the mold 1 can be divided into a plurality of parts by a mold part not shown, and when the cast product after casting is taken out, the mold 1 is parted and taken out. Further, at the time of casting, in order to keep the temperature of the mold 1, the mold 1 was placed on the sand and kept warm.

  For casting, AC4C alloy, AC4CH alloy and AC7A alloy were used. Each chemical component is shown in Table 1. In the following description, an AC4CH alloy will be described, but AC4C was similarly tested.

  The alloys shown in Table 1 were poured simultaneously from the gates 3a and 3b of the mold 1 respectively. The pouring temperature of AC4CH was the liquidus temperature of AC4CH + 60 ° C. and the liquidus temperature of AC7A + 20 ° C. In addition, each pouring amount and pouring speed were the same.

  FIG. 2 is a view showing the casting 7 manufactured as described above. The casting 7 is formed by the cavity of the mold 1. In addition, the site | part corresponding to the gates 3a and 3b becomes the feeder parts 9a and 9b. The feeder parts 9 a and 9 b are parts for supplementing the volume reduction in the solidification shrinkage of the casting 7.

  The casting 7 has a plate shape in which the feeder parts 9 a and 9 b are joined together at the joining part 5. Note that the test piece portion extends from the upstream side (C portion in the figure) of the merging portion 5 to the vicinity of the end portion (D portion in the drawing) of the casting 7 on the downstream side of the merging portion 5. That is, in the test piece part, the feeder part 9a side (for example, AC4CH) and the feeder part 9b side (for example, AC7A) are integrated with the joining part 5 as an alloy boundary.

  The length of the test piece (length from C to D in the figure) is about 150 mm. As a sample for mechanical testing, a plurality of test pieces 11a... 11j were cut out in the width direction of the product part so as to straddle the joining part 5 of the product part. The length of the test piece 11 was 70 mm, the width was about 10 mm (the grip margin width was 15 mm), and the thickness was 5 mm. In FIG. 2, six test pieces 11 are shown for simplicity, but ten actual test samples 11a to 11j were collected.

  FIG. 3 is a diagram showing the tensile test results of the test pieces 11a to 11j with AC4CH, FIG. 3 (a) is a test piece photograph after the tensile test, and FIG. 3 (b) is the tensile strength of each test piece. It is a figure which shows a change. The tensile test was performed based on JISZ2241. The alloy boundary 13 in FIG. 3A is a portion corresponding to the joining portion of the casting 7. In the drawing, the left side is the test piece 11a, and the right side is the test piece 11j.

  The fracture position was not limited to the position of the alloy boundary 13, and fractures were observed at sites other than the alloy boundary 13. That is, it can be seen that the alloy boundary 13 is not a strong defect.

  FIG. 3B shows the tensile strength, and the sampling position is the distance from the upstream side of the product. That is, the sampling position of 0 mm is the most upstream part of the merging part, and indicates the sample of part C in FIG. Moreover, FIG.3 (b) is the tension test result which repeated the same test 3 times, and the square point, the round point, and the triangular point in a figure are each test result.

  As shown in FIG. 3B, the tensile strength showed an extremely low value although there was some variation. Moreover, the tendency of intensity change depending on the site was not confirmed. In particular, there was no significant difference in strength between the case where fracture occurred at the alloy boundary 13 and the case where fracture occurred at other sites.

  FIG. 4 is a diagram showing a change in tensile strength of each test piece in a test using AC4C instead of AC4CH, as in FIG. FIG. 4 shows tensile test results obtained by repeating the same test twice, and square points and round points in the figure are the test results. Even in the case of AC4C, as with AC4CH, although the tensile strength varies somewhat, it has shown an extremely low value. In addition, the dotted line (E part) in FIG. 4 shows the tensile strength in general AC4C, and as can be seen from FIG. 4, the tensile strength in each test piece is a general alloy that does not have a joining part or the like. Compared to strength, it was not significantly inferior.

  Next, the bending test result of the test piece will be described. FIG. 5A shows the result of a bending test performed on the test piece 11 of AC4CH. The bending test was performed based on JISZ2248. However, since the boundary portion had a certain width, the distance between the supports was set to 50 mm (according to JIS, 25 mm ± 5 mm).

  A dotted line (part F) in the figure is a representative value in a test result using JIS-AC4CH alone. From the results, it can be seen that the test piece having the merging portion has the same bending strength as the test piece having no merging portion (F portion).

  Similarly, AC4C was also tested. FIG. 6A shows the result of a bending test performed on the AC4C test piece 11. The test piece used for the bending test was cut out from a casting sample as shown in FIG. FIG. 6 (b) is a schematic view of only the test piece portion viewed from above, excluding the feeder part of the casting, and the molten metal flows from the left side to the right side in the figure. That is, the left end of FIG. 6B corresponds to the sampling position 0 mm position (C portion in FIG. 2), and the right end of FIG. 6B corresponds to the sampling position 150 mm position (D portion in FIG. 2). In this test, the merged portion (boundary portion) is shifted from the center of the casting in the downstream portion, and only the AC7A is located in the center of a part of the sample on the downstream side (that is, the boundary portion has shifted from the central position). ). For this reason, the test was also performed on a test piece whose central part was not a boundary part.

  On the right side (ie, downstream side) of the dotted line (G portion) in FIG. 6A, the bending position of the bending test is considered to be the AC7A alloy portion, not the boundary portion. However, from the results, even in the test piece having the boundary portion (upstream side test piece), there is no large variation, and details are omitted, but for example, it is comparable to the bending strength of AC4CH in FIG. It was a thing. Note that the bending strength on the right side of the portion G is larger due to the high elongation of AC7A.

  Next, the structure observation results near the boundary will be described. As for the following results, only the test results with AC4CH are shown, and the same results were obtained with the test with AC4C, and therefore the description of the results with AC4C is omitted. FIG. 7 shows the result of observing the structure near the boundary cut out from the casting 7 with a metallographic microscope. As shown in FIG. 7A, the left side is the AC7A alloy part 15, the right side is the AC4CH alloy part 19, and the boundary part 17 is between them. The boundary portion 17 is a portion where AC7A and AC4CH flow from both sides and merge.

  As can be seen from FIG. 7 (a), the metal structures of the AC7A alloy part 15 and the AC4CH alloy part 19 were uniform. In addition, at the boundary portion 17, the tissue continuously changed depending on the location. That is, the vicinity of the AC7A alloy part 15 has substantially the same structure as that of the AC7A alloy part, and the form of the structure gradually changes as the distance from the AC7A alloy part 15 increases. In the vicinity of the AC4CH alloy part 19, the structure becomes substantially the same as that of the AC4CH alloy part. That is, the organization of the boundary portion 17 is continuously changing, and the organization is not locally changed. The width of the boundary part 17 was 400 μm or more.

  FIG. 7B is a photograph in which the structure at the boundary portion 17 in FIG. 7A is observed with an increased magnification. The form of the eutectic 18 (dark gray in the photograph) slightly changes depending on the site. However, coarse intermetallic compounds and intermetallic compounds did not precipitate locally. That is, the amount of intermetallic compound produced at the boundary portion 17 was between the amount of intermetallic compound produced in each of the AC7A alloy portion 15 and the AC4CH alloy portion 19, and the amount of intermetallic compound produced also changed continuously.

  FIG. 8 is a diagram showing a composition change. As for the composition change, line analysis was performed so as to cross the boundary portion, and the change in the components of Si, Al, and Mg was investigated. The composition of each element in the figure indicates that the concentration is higher toward the top of each component. The composition change was measured by line analysis using an energy dispersive spectrometer (EDX (Energy Dispersive X-ray Spectroscopy)).

  In the AC7A alloy part, Mg showed a high value. The variation of the Mg component in the AC7A alloy part depends on the distribution of α phase, eutectic and the like, and can be said to be a uniform component macroscopically.

  On the other hand, in the AC4CH alloy part, Mg was low and Si was high. Note that the variation of the Si component in the AC4CH alloy part depends on the distribution of α phase, eutectic and the like as described above.

  From the results, the Si and Mg compositions at the boundary portion continuously changed from the AC7A alloy portion to the AC4CH alloy portion. That is, no Si or Mg peaks were observed at the boundary, and both Si and Mg at the boundary were between the composition in the AC7A alloy part and the composition in the AC4CH alloy part.

  Next, for the sake of comparison, conventional casting was performed. FIG. 9 is a diagram showing a casting method using cast-in. First, as shown in FIG. 9A, solid AC4CH is installed in the mold 29. The mold 20 is made of cast iron. Solid AC4CH was obtained by casting separately. Solid AC4CH occupies approximately half of the template 20. Subsequently, as shown in FIG. 9B, the liquid AC7A is poured into the mold 20. The liquid AC7A has a temperature equal to or higher than the liquidus temperature. The boundary between the solid AC4CH and the liquid AC7A is the alloy boundary 25.

  FIG. 10 is a view showing a structure observation result in the vicinity of the alloy boundary 25 in FIG. As shown in FIG. 10A, a boundary portion 31 is formed between the AC4CH alloy portion 27 and the AC7A alloy portion 29. As can be seen from FIG. 10A, the metal structures are uniform in the AC4CH alloy part 27 and the AC7A alloy part 29, respectively. On the other hand, in the boundary part 31, the structure of the AC7A alloy part 29 and the structure of the AC4CH alloy part 27 are rapidly changed. The width of the boundary portion 31 was about 50 μm.

FIG. 10B is a photograph obtained by observing the structure in the vicinity of the boundary 31 with an increased magnification, and FIG. 10C is a schematic diagram of FIG. A large amount of band-like intermetallic compound 35 (Mg ₂ Si) was confirmed at the boundary portion 31. In addition, the form of the eutectic 33 changed abruptly with the boundary portion 31 as a boundary.

  FIG. 11 is a diagram showing a composition change in the vicinity of the boundary portion 31 as in FIG. 8. The boundary portion has a width of about 50 μm, and the composition of Si and Mg changes abruptly at the boundary portion. In particular, a large Si peak is confirmed at the boundary. The Si peak is due to an intermetallic compound or the like. In this way, in the method using cast-in, the components are not continuous at the boundary portion, and the peaks of some components are confirmed.

  In addition, although the component dispersion | variation of Mg and Al in an AC7A alloy part is large, since AC7A was created in the boat-shaped mold made from cast iron, the cooling rate was slow and the structure became coarse. In any case, it can be seen that in the method using the cast-out, the composition is not continuous at the boundary, and a large amount of intermetallic compounds are precipitated.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

The figure which shows the casting_mold | template 1. FIG. The perspective view which shows the casting. The figure which shows the tension test result of the test piece 11 using AC4CH. The figure which shows the tension test result of the test piece 11 using AC4CH. The figure which shows the tension test result of the test piece 11 using AC4C. The figure which shows the bending test result of the test piece 11 using AC4CH. It is a figure which shows the bending test result of the test piece 11 using AC4C, (a) is a test result, (b) is a schematic plan view of a casting. The figure which shows the structure | tissue of the boundary part 17 vicinity. The enlarged view which shows the structure | tissue of the boundary part 17 vicinity. The figure which shows the organization change across a boundary part. The figure which shows the casting_mold | template 20. FIG. The figure which shows the structure | tissue of the boundary part 31 vicinity. The enlarged view which shows the structure | tissue of the boundary part 31 vicinity. The schematic diagram which shows the structure | tissue of the boundary part 31 vicinity. The figure which shows the organization change across a boundary part.

Explanation of symbols

1 ......... Molds 3a, 3b ......... Mouth 5 ...... Merging portion 7 ......... Castings 9a, 9b ......... Feed portion 11 ......... Specimen 13 ...... Alloy boundary 15 ......... AC7A alloy Part 17 ......... Boundary part 18 ......... Eutectic 19 ......... AC4CH alloy part 20 ......... Mold 25 ......... Alloy boundary 27 ......... AC4CH alloy part 29 ......... AC7A alloy part 31 ......... Boundary Part 33 ... Eutectic 35 ... Intermetallic compound

Claims (1)

A first alloy part;
A second alloy part that is integrated with the first alloy part and has a component different from that of the first alloy part;
The α phase and the eutectic size of the boundary portion between the first alloy portion and the second alloy portion continuously change from a homogeneous structure in each alloy portion . From the first alloy part to the second alloy part, the Mg concentration increases continuously, the Si concentration decreases continuously ,
The first alloy part is a JIS-AC4C alloy,
The second alloy part is a JIS-AC7A alloy,
An intermetallic compound is precipitated at the boundary portion, and the amount of the intermetallic compound deposited at the boundary portion continuously changes between the first alloy portion and the second alloy portion. And the width of the boundary is 400 μm or more,
The aluminum alloy casting , wherein the intermetallic compound is Mg ₂ Si .