JPH03134252A - Aluminum alloy compound member for internal combustion engine - Google Patents

Abstract

PURPOSE:To contrive the improvement of wearing resistance by reinforcement- compounding a chrome-contained porous metal with an aluminum alloy and preferentially shaving by lapping work an aluminum alloy area to the porous metal to form a fine oil reservoir. CONSTITUTION:A bore part 2 in an aluminum alloy-made cylinder block 1 is reinforced by compounding a porous metal plate, having a volume factor 6 to 30% preferably 8 to 20% and a chrome content 10 to 55% preferably 15 to 55%, with an aluminum alloy. When a surface 11 of an aluminum alloy compound member is lapped while allowing a lapping agent to flow, the aluminum alloy 4 is preferentially shaved to the porous metal 3 with a pit 13 and a groove 14 formed as an oil reservoir, while an amount of a hard grain 17, which is an Si grain, is decreased by lapping work. Thus, the improvement of wearing resistance and scuffing resistance can be contrived.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an aluminum alloy composite member for internal combustion engines, which is a composite of porous metal and aluminum alloy, and is suitable for use in sliding parts of internal combustion engines. be.

[Summary of the invention]

The aluminum alloy composite member for internal combustion engines of the present invention has excellent durability by strengthening the porous metal as a composite reinforcing material by combining it with an aluminum alloy and by lapping the surface to form fine oil pockets. This provides abrasion resistance and allows lubricating oil to accumulate effectively on the sliding surface.

[Conventional technology]

Cylinder blocks for internal combustion engines made of aluminum alloy can significantly reduce the weight of the engine compared to, for example, cast iron cylinder blocks, have better heat dissipation, and can reduce the assembly gap with aluminum alloy pistons. It has the advantage of being able to reduce noise due to For this reason, there is a tendency for cylinder blocks made of aluminum alloy to be increasingly adopted.

Conventional methods for reinforcing the bore of an aluminum alloy cylinder in which a piston moves reciprocally and improving its wear resistance can be roughly divided into the following three types.

■Improvement of the aluminum alloy itself ■Surface treatment of the bore of the cylinder ■Composite reinforcement of the aluminum alloy with ceramic fibers or particles [Problem to be solved by the invention] However, all of the above methods have the following drawbacks. .

■Reynolds is a typical example.
There is a St-rich aluminum alloy A39O manufactured by Co., Ltd., which is widely used mainly in Europe. This alloy achieves wear resistance by embossing hard primary Si particles, but high-St aluminum alloys have poor castability and poor machinability, resulting in high production costs.

Also, an alloy has been proposed in which graphite particles are dispersed in an aluminum alloy to improve lubricity. Since the mechanical strength of this alloy decreases due to the addition of graphite, it is being considered to put this alloy to practical use only as a liner for cylinder bores. Methods for manufacturing this alloy include casting methods and extrusion methods. According to the casting method, in order to suppress the reaction between the graphite and the molten aluminum alloy during casting, the graphite particles must be subjected to a surface treatment such as Ni plating in advance, which increases the cost. Furthermore, it is often difficult to uniformly disperse graphite particles and cast them.Furthermore, the extrusion method is a method in which aluminum powder and graphite powder are extruded and sintered, but the graphite is stretched in the extrusion direction. It has not been put into practical use because of the problem that the wear resistance is not very good.

For the surface treatment of (2), Cr plating, SiC or Ti
There is Ni dispersion plating in which hard fine particles such as B are dispersed in Ni plating, and these are often used in aluminum alloy cylinders of two-stroke engines. However, applying this surface treatment to a large cylinder block such as a 4-stroke gasoline engine requires masking the parts other than those to be plated before immersing it in a plating bath, making this masking process difficult and expensive. Therefore, it is not suitable for mass production.

Methods for composite reinforcement of aluminum alloys include, for example, composite reinforcement with inorganic fibers such as Af and 03 fibers;
There is also a method of composite reinforcement in which inorganic particles such as Si nitride are dispersed in a molten aluminum alloy and cast by die casting (Japanese Patent Application No. 149186/1986). Aluminum alloy cylinders composite-reinforced by these methods have not been put into practical use because of the presence of thin, hard inorganic fibers and particles that cause piston rings and pistons to wear out during use. In addition, the patent application 1986-
No. 102802, Japanese Patent Application No. 61-141830, and Japanese Patent Application No. 63-38542, A lz
O: +-5iOz fiber or AI! It has been proposed to use a combination of 203 fibers and C fibers, and to protect the mating sliding part by plating, thermal spraying, etc. in order to improve wear resistance and scuffing resistance. In this way, when an aluminum alloy composite member using a hard composite reinforcing material such as inorganic fiber is used for one sliding member, the hard fibers sparsely protruding into the aluminum alloy of this composite member are Since the other sliding member is ground and worn, both members must be selected and combined depending on the properties of the other member.

An object of the present invention is to provide an aluminum alloy composite member for an internal combustion engine that prevents damage such as wear to a mating sliding member and improves its own wear resistance and scuffing resistance. That's true.

[Means to solve the problem]

To achieve the above object, the aluminum alloy composite member for internal combustion engines of the present invention has a volume fraction of 6 to 30%, preferably 8 to 20%, and a chromium content of 10 to 55%, preferably 15 to 55%. The porous metal is strengthened by combining it with an aluminum alloy, and at least a part of the area made of the aluminum alloy exposed on the surface is removed preferentially than the porous metal by lapping to create a fine oil pool. was formed.

The porous metal preferably has a volume fraction within the above range by compressing a porous metal having a porosity of 85 to 98% in one direction.

In addition, the composite of aluminum alloy and the above porous metal is
This can be done by infiltrating molten aluminum alloy into this porous metal.

Further, the porous metal as the composite reinforcing material is preferably made of a material harder than an aluminum alloy, such as a material made of iron, nickel, or the like.

[Effect]

Since the porous metal is composited with an aluminum alloy, by forming the porous metal into a desired shape in advance, it becomes possible to compositely strengthen only the necessary portions.

The porous metal body has a volume fraction of 6% or less,
As the ratio of the composite reinforcing material in the composite member decreases, the effect of improving the wear resistance of the composite member decreases, and if it exceeds 30%, the permeability of the aluminum alloy into the porous metal when composite is reduced. descend.

The chromium content of the porous metal needs to be 10 to 55%, but this is because if the chromium content is 10% or more, the metal will become brittle when the aluminum alloy and the porous metal are combined. This is because the formation of compounds can be suppressed and the strength of the interface between the aluminum alloy and the porous alloy can be increased. If a brittle intermetallic compound is formed, cracks may occur from the intermetallic compound.

Furthermore, by containing chromium, the porous metal increases its hardness and improves the wear resistance of the composite part. However, even if it contains 55% or more of chromium, its wear resistance does not improve much. Furthermore, since this hardness is smaller than that of inorganic fibers and particles, there is less risk of damaging the sliding portion of the other party, for example.

The porous metal and the aluminum alloy are exposed on the surface of the aluminum composite member in which the porous metal is composited, but the aluminum alloy is softer than the porous metal containing chromium. Therefore, at least a portion of the region made of the aluminum alloy is polished preferentially to the porous metal by lapping to form minute depressions or bits. Since these serve as oil reservoirs for the lubricating oil used within the internal combustion engine, the lubricating oil can be effectively stored on the surfaces thereof.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In this example, a cylinder pore portion which requires wear resistance and scuffing resistance in a cylinder body of an internal combustion engine is constructed using the aluminum alloy composite member of the present invention.

First, as previously proposed by the inventors of the present application in Japanese Patent Application No. 1-149220, a plate-shaped porous metal having a porosity of 85 to 98% is preferentially compressed in one direction to achieve a volumetric ratio. Vt6～
30%, preferably 8-20% porous metal plate.

This porous metal functions as a reinforcing material for the composite member, and by compressing the porous metal, the volume fraction of the porous metal is increased, and the wear resistance of the composite material is improved.

If the volume fraction of the porous metal plate is less than 6%, the effect of improving wear resistance is small, and if it is more than 30%, it becomes difficult to combine with an aluminum alloy. When a porous metal is preferentially compressed in one direction, the diameter of the pores of the porous metal viewed from the compression direction hardly changes compared to the diameter before compression.

Therefore, when a porous metal and an aluminum alloy are combined, the permeability of the aluminum alloy into the porous metal hardly changes compared to when the porous metal is used before compression. Further, a processing method in which porous metal is compressed uniformly using hydrostatic pressure is not preferable because the volume fraction becomes high. Further, from the viewpoint of wear resistance, it is desirable that the porous metal be made of a material such as iron or nickel that is harder than the aluminum alloy.

Next, the porous metal plate is formed into a cylindrical shape to form a cylinder bore, and chromium is diffused into the cylindrical porous metal to contain 10 to 55% chromium.

When a porous metal such as iron or nickel is combined with an aluminum alloy, it reacts with aluminum or the like to form a brittle intermetallic compound at the interface thereof. When such an aluminum composite member is used, for example, in a piston of an internal combustion engine and the piston is subjected to thermal cycles of heating and cooling over a long period of time, cracks may occur from the brittle intermetallic compound portions. In contrast, the inventors of the present application previously filed the patent application No. 63-222239.
In the above, the above-mentioned brittle intermetallic compound is formed by using a porous metal with a layer of 0.001 m or more formed by chromizing treatment etc. on the surface so that the chromium content is 10% or more, preferably 15% or more. It has been shown that it can be suppressed. Furthermore, by containing up to 55% chromium, the porous metal can be made harder and have improved wear resistance.

Next, the cylindrical porous metal body is set in a mold for casting a cylinder block. Then, when the cylinder block is cast using a pressure casting method, the molten aluminum alloy permeates into the porous metal.

FIG. 1 shows a longitudinal section of the bore portion of the aluminum alloy cylinder block 1 manufactured as described above, and the cylinder bore portion 2 is compositely reinforced by the porous metal 3. When the cylinder block 1 is manufactured in this way, the cylinder bore 2, which is likely to suffer wear and scuffing due to the reciprocating movement of the piston (not shown), is reinforced by a porous metal 3 with wear resistance. can do. Moreover, this combination can be performed simultaneously when manufacturing the cylinder block 1.
In addition, only the bore part 2, which is the part that requires wear resistance, can be made of porous metal 3, and most other parts can be made of aluminum alloy 4, so it can be easily manufactured and the material cost does not increase much. . In this case, since the pressure casting method is used, the strength of the aluminum alloy is improved and casting defects are reduced.

Next, the cylinder bore portion 2 is subjected to surface finishing. FIG. 2 shows an enlarged view of the metallographic structure of the cylinder bore surface 11. In FIG. 2, the dotted portions are regions made of porous metal 3, and the white portions are regions made of aluminum alloy 4. On the surface 11 of this aluminum alloy composite member, porous metal 3 exists like islands in aluminum alloy 4, and aluminum alloy 4 exists like small islands in relatively large porous metal 3. You can see that it exists.

Next, lapping is performed on the cylinder bore surface 11 as described above while flowing a lapping agent made of a slurry in which hard fine particles such as SiC are suspended. A partially enlarged view and a partially enlarged perspective view of the surface 11 after this lapping process are shown in FIGS. 3 and 4, respectively. As shown in FIGS. 3 and 4, pits 13 and grooves 14 are preferentially formed in the region made of the aluminum alloy 4.

This is because the composite member is composed of porous metal 3 and aluminum alloy 4, which are different phases with different hardnesses, and Alchrome is 20
The hardness of a porous metal made of nickel that has been infiltrated with nickel is about 250 to 300 in terms of Vickers hardness (measured using a micro Vickers hardness meter), while the hardness of aluminum alloys, such as AC8A specified by JIS, is Brinell hardness. The hardness is approximately 100 (approximately 115 in terms of Vickers hardness). While pressing a lapping shoe made of cast iron FC15 specified by JIS against such a bore surface 11 at a pressure of 0.2 kg/cni, the number of times is 10 Or, p, m, and the stroke is 100.
It was slid under the conditions of n. At the same time, a lapping agent made of a slurry of a lubricant with a viscosity of 1200 cs mixed with SiC particles of about 400 mesh was dropped between the shoe surface and the bore surface 11.

By rolling the SiC particles on the surface 11 and rubbing the surface 11, a part of the region made of the aluminum alloy 4 was scraped off, and a pit 13 having a depth of 1 to 10 μm was formed. Thereafter, by lightly polishing the surface 11 with a shoe made of cork or rubber to remove the protrusions caused by the bulges of the aluminum alloy around the pits 13, a uniformly distributed depth can be obtained in the area made of the aluminum alloy 4. Pit 13 of 1 to 4 μm was formed. At the same time, grooves 14 were formed by rubbing the surface 11 relatively long in one direction by the SiC particles.

Although the processing conditions described above can be changed as appropriate, pits 13 and/or
Or, in order to form the groove 14, the shoe pressure is 0.0.
5~1.0 kg/co! is desirable. This pressure is 1
,0 kg/cn! If it exceeds this value, many pits and grooves will be formed in the region made of the porous metal 3, which is not desirable.

In addition, it is possible to keep the shoe pressure relatively low and for a relatively long time (
0.5 to 3 minutes), the entire region made of aluminum alloy 4 is shaved off and becomes concave. A cross-sectional view of the surface 11 which has been lapped in this manner is shown in FIG. As shown in FIG. 5, the area made of the aluminum alloy 4 is removed more than the area made of the porous metal 3, so that the area made of the aluminum alloy 4 on the surface 11 shown in FIG. The entire structure is depressed to form a recess 12, and the porous metal 3
The area consisting of is relatively prominent.

The pits 13 and grooves 14 remain as they are on the surface of the region of the aluminum alloy 4 in the recess 12. According to this processing, the depth d of this recess 12 is approximately 0.2
~2.0 μm.

In order to lubricate the reciprocating movement of the piston in the cylinder bore 2, lubricating oil forms an oil film between the bore surface 11 and the surface of the piston.
Lubricating oil can accumulate in the recesses 12, pits 13, and grooves 14 formed in the housing 1. Since all of these function as oil reservoirs and maintain the oil film well, the lubricity and scuffing resistance in the gap are improved.

In particular, when a composite member of aluminum alloy 4 and porous metal 3 is used in the cylinder bore, scuffing occurs in the region made of soft aluminum alloy 4, so the region made of aluminum alloy 4 is shown in FIG. As shown, it is preferable to have a concave condition as a whole, and it is preferable that the concave part 2 further has a pit 13 and/or a groove 14, since this further increases the effect of storing lubricating oil.

In addition, the hard particles used for wrapping are 200 to 80
One with 0 mesh is preferable. If coarse particles exceeding 200 meshes are used, the depth and size of the pits and grooves will become too large and the consumption of lubricating oil will increase, which is undesirable. If fine particles of less than 800 meso particles are used, the ability to form pits and grooves will decrease, which is not preferable. Furthermore, when lapping is performed, the SiC particles 17 as hard particles become small lumps and are slightly embedded in the aluminum alloy 4, as shown in FIGS. 3 and 4, but in this case, the hard particles are The larger the size, the greater the wear on the piston, which is the sliding member on the other side. In addition, in this regard, the lower the pressure of the shoe in the wrapping process, the less the amount of embedded hard particles will be, so a pressure of 1.0 kg/c+d or less as mentioned above is preferable. Further, for this reason, it is more preferable that the hard particles have a particle size of 400 to 800 mesos.

Note that the above-described lapping process is also commonly used as a surface finishing method for the cylinder bore portion 2. Therefore, since the oil reservoir as described above can be formed at the same time as the surface finishing of the bore part 2 after the composite, it is possible to obtain the sill block 1 having the sill bore part 2 with improved scuffing resistance using a low-cost manufacturing method. .

Hereinafter, specific examples and comparative examples of the aluminum alloy composite member of the present invention will be explained with reference to Example 1.2 and Comparative Examples 1 to 4.

After compressing a 5 mm thick plate of porous metal made of nickel (Sumitomo Electric Industries, Ltd., Ni Selmeft #6) from one direction to a thickness of 311 mm, this porous metal plate was It was shaped into a cylinder of approximately 100++n.

Next, by applying chromizing treatment to this cylindrical porous metal, chromium is diffused and permeated, and chromium is 35%
% was included.

Next, this cylindrical porous metal body is set in a mold, and aluminum alloy AC8 specified by JIS is placed in this mold.
A hollow cylindrical aluminum alloy composite member with a volume fraction of porous metal as a composite reinforcing material of about 10% was created by pouring the molten metal A at a temperature of 760°C under a pressure of 700 kg/cIa. This hollow cylindrical body was subjected to so-called T6 treatment specified by JIS, and then the inner surface of the hollow cylindrical body was cut. Next, this hollow cylindrical body was set on a lapping machine, and 600 meshes of SiC particles with a viscosity of 1
A ramping agent consisting of a slurry mixed with 200cs of lubricant was injected, and a shoe made of extremely soft cast iron (F 15 C) was adjusted to a pressure of 0.12kg/w'' to the inner surface of the hollow cylindrical body. I pressed it.Then, the number of revolutions was 10.
The lapping process was performed for 2 minutes under the conditions of Or, p m, and a stroke of 100 n. Subsequently, the above shoe was replaced with a rubber shoe and lapping was performed for 30 seconds at a pressure of 0.2 kg/- (no lapping agent was used), so that the entire area mainly made of aluminum alloy 4 was coated to a depth. A recess 12 of about 0.2 to 1.5 μm was formed, and numerous pits 13 and grooves 14 of a depth of 2 to 3 μm were formed on the surface of the recess 12.

Hokkai ■ Cast iron with flaky graphite (C: 3.1%, B: 0.0
6%, Si: 2.0%, Mn: 0.7%, P: 0.3%
, Fe: remainder), a hollow cylindrical body having the same shape as in Example 1 was created, and the inner surface was plateau honed.
The roughness was set to ~3 μm.

几MJ, YukiL Aluminum alloy (Si: 17%, Cu: 4.
5%, Mg: 0.5%, A1: remainder), 50~
A hollow cylindrical body having the same shape as in Example 1 was created by casting so that primary crystal Si of 70 μm was uniformly dispersed. After this hollow cylindrical body was subjected to T6 treatment, the inner surface of the hollow cylindrical body was cut, and then honed and finished to 0.
The roughness was set to 5 μm or less. Next, this inner surface was electrolytically etched in a solution of Na nitrate, so that Si particles of about 1 μm were raised on the inner surface.

Kokai Kanshu A I J3-3t (h fiber (^βzoi: 50%, volume fraction Vf: 9%, shot: 1% or less; manufactured by Nichias)
The temperature of aluminum alloy AC8A in the cylindrical molded body is 760℃.
A hollow cylindrical body having the same shape as in Example 1 was created by infiltrating the molten metal at a temperature of 800 k+r/cni to form a composite. After T6 treatment of this hollow cylindrical body,
The inner surface of the hollow cylinder was cut and then honed to a roughness of 1 μm or less. Next, an electrolytic etching process was performed so that the aluminum alloy portion between the fibers on the inner surface became a recess of about 2 μm.

1. On the inner surface of a hollow cylindrical body made of aluminum alloy AC8A (the same shape as in Example 1), Si particles having a size of 3 μm or less were dispersed in Ni to a concentration of about 3% by weight, and a thickness of about 80
Ni dispersion plating with a thickness of μm was applied.

Next, this inner surface was honed to a surface roughness of 1 to 2 μm.

In Example 2, the aluminum alloy in Example 1 was
A similar hollow cylindrical body was created under the same conditions as in Example 1, except that AC9B specified by IS was changed, and the same treatment was performed.

Test pieces were cut out from each of the hollow cylindrical bodies of Example 1.2 and Comparative Examples 1 to 4 above, and abrasion tests on these test pieces were conducted using an Okoshi type abrasion tester.

The rotor of the test machine having a sliding surface with the test piece was made of cast iron, which is the same material as in Comparative Example 1. An indentation by a triangular pyramid was formed on the outer circumferential surface of the rotor that slid against the test piece. Before and after the wear test, the amount of wear on the rotor itself was also measured by measuring the diagonal length of the indentation using a microscope. The test conditions for the above wear test were: friction distance: 570m;
The friction speed was -0.12 m/sec, the load was 19 kg, and the dripping rate of lubricating oil (SAECC class #30) was 3 cc/min. The abrasion test results of the above Examples 1.2 and Comparative Examples 1 to 4 are shown in FIGS. 6 and 7.

Figure 6 shows the specific wear amount of each test piece, and Figure 7 shows the wear amount of the rotor measured in the wear test of each test piece.
The figures are shown based on the wear amount of the rotor measured in the comparative example.

From this FIG. 7, the above-mentioned Example 1.2 and the above-mentioned Comparative Examples 1-
It is possible to know the degree of damage caused by each member of No. 4 to the sliding member on the other side. From Figures 6 and 7, it can be seen that Comparative Example 3 (aluminum alloy A7!201-5i (compositely reinforced with H fiber) had the smallest specific wear amount, but the sliding member on the other side It can be seen that this causes the most damage. This is because the fibers mentioned above are extremely hard. Also, Comparative Example 1 (cast iron material) and Comparative Example 4 (Ni dispersion plated material) are materials that have been used in the past. However, the materials of Examples 1 and 2 of the present invention exhibited wear resistance comparable to these, and the material of Example 2 was found to have further improved wear resistance than the material of Example 1. Recognize.

[Modified example]

FIG. 8 shows a modification in which the cylinder liner 15 is made of the aluminum alloy composite member of the present invention.

This cylinder liner 15 is made of a porous metal 3 formed into a cylindrical shape and composited with an aluminum alloy 4 by the method described above. This inner surface 11 constitutes the cylinder bore portion 2, and by performing the same processing as described above, a recess 12 as an oil reservoir, a bit 13, and a groove 14 are formed in this inner surface 11. This cylinder liner 15 is inserted into the bore portion of the cylinder and fixed by a method such as shrink fitting or cold shrinking. By using such a cylinder liner 15, cylinder blocks for internal combustion engines can be manufactured using inexpensive casting methods such as low-pressure casting and gui-casting, and processes such as plating are not required, resulting in a reduction in manufacturing costs. can. Note that if the aluminum alloy used in the composite is an aluminum alloy containing a large amount of Si, the wear resistance of the cylinder liner 15 can be further improved.

〔Effect of the invention〕

Since the present invention has the above-described configuration, the aluminum composite member for an internal combustion engine of the present invention has the following effects.

■ Since porous metal is used as the material for composite reinforcement, only the parts that are subject to significant wear can be composite reinforced. Furthermore, it is possible to select the most suitable aluminum alloy from the viewpoint of the overall characteristics of the internal combustion engine.

(2) Since a porous metal having an appropriate volume fraction is used, it is possible to improve the wear resistance of the aluminum alloy composite member due to the porous metal, and it is possible to perform the composite with the aluminum alloy without any problem.

■ Since porous metal with an appropriate ROM content is used, the formation of brittle intermetallic compounds that occur when porous metal and aluminum alloy are combined can be suppressed, and the interface between porous metal and aluminum alloy can be suppressed. In addition to increasing the strength,
The hardness of porous metals can be increased and the wear resistance of composite reinforced materials can be improved. Furthermore, since this hardness is smaller than that of inorganic fibers and particles that are conventional composite reinforcing materials, there is less risk of damaging, for example, the sliding portion of the other party.

(2) Since an oil reservoir is provided in which the lubricating oil in the internal combustion engine can accumulate, the lubricity and scuffing resistance of the portion where the oil reservoir is provided can be improved.

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention,
Fig. 1 is a vertical sectional view of the bore portion of a cylinder block of an internal combustion engine using the aluminum alloy composite member of the present invention;
The figure is a partially enlarged plan view of the surface of a cylinder bore made of an aluminum alloy composite member, FIG. 3 is a partially enlarged plan view showing pits and grooves formed as oil reservoirs on the cylinder bore surface, and FIG. 4 is the same ( FIG. 5 is a partially enlarged perspective view showing pits and grooves formed as oil pools; FIG. 5 is a cross-sectional view showing recesses, pits, and grooves also formed as oil pools;
The figure shows the specific wear amount of each material of the example and comparative example measured by the wear test. FIG. 8, which shows the normalized amount of wear, is a vertical sectional view of a modified cylinder liner. In addition, in the symbols used in the drawings, 3 ------------ Porous metal 4 .--
−・−−−−−1−・−・Aluminum alloy 12−・・
・−・−・ Concavity (oil pool) 13 ・−・−・・−
・−・−・・−・Pit (oil sump) 14−−−−−−−
--------...Groove (oil pool).

Claims (1)

[Claims] 1. The volume fraction is 6 to 30% and the chromium content is 10 to 5.
5% of the porous metal is combined with the aluminum alloy, and at least a part of the area made of the aluminum alloy exposed on the surface is removed preferentially than the porous metal by lapping to create fine particles. An aluminum alloy composite member for internal combustion engines characterized by forming an oil reservoir. 2. The aluminum alloy composite member for an internal combustion engine according to claim 1, wherein the porous metal is obtained by unidirectional compression molding of a porous metal having a porosity of 85 to 98%. 3. The aluminum alloy composite member for an internal combustion engine according to claim 1 or 2, wherein the porous metal is made of iron or nickel.