JP3077865B2 - Iron-based alloy powder for sintering and wear-resistant iron-based sintered alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintering iron-based alloy having excellent compressibility and corrosion resistance useful for sintered parts such as valve seats, piston rings or exhaust system collars used in internal combustion engines. The present invention relates to a powder and an iron-based sintered alloy having excellent wear resistance.

[0002]

2. Description of the Related Art Conventional valve seat materials include Fe.
Intermetallic compounds such as ferromolybdenum (Fe-Mo) and ferrochrome (Fe-Cr) or Fe-C for the purpose of improving wear resistance of -C-Co-Ni-based material and Fe-C-based material
-Cr-Mo-V alloy or the like is used (JP-A-56-154110).

Further, Fe— containing Cr and Mo
A sintered alloy in which iron-based hard particles composed of Cr, Mo, V, etc. are dispersed in a C base structure to improve abrasion resistance and aggressiveness to a partner (Japanese Patent Laid-Open No. 60-224762), and Fe-C-
A sintered alloy in which hard particles made of FeMo and FeW are dispersed in a Co-Ni base matrix and impregnated with a Pb alloy or the like to improve wear resistance (Japanese Patent Laid-Open No. 62-202058)
Gazette).

[0004] The characteristics required for the valve seat material include corrosion resistance and heat resistance in addition to wear resistance.
Hard particles are mainly responsible for wear resistance, and corrosion resistance and heat resistance are mainly responsible for base structures, and the two are combined to ensure durability.

[0005]

In recent years, there has been a growing demand for improvement in automobile engines for longer life, higher output, higher rotation speed, measures for purifying exhaust gas, or measures for improving fuel efficiency. For this reason, it has become unavoidable for engine valves and valve seats in automobile engines to withstand more severe use environments than ever before, and heat resistance and wear resistance are further improved, and at high temperatures. It has become necessary to improve the corrosion resistance of steel.

[0006] However, the formation of the base of the conventional iron-based valve seat material is based on the alloying elements Ni, C
After mixing elemental powders of the respective elements such as o, Mo, etc., the mixed powder is molded and sintered as a raw material to obtain Ni, Co, Mo.
Etc. are diffused in iron. For this reason, it is difficult to completely diffuse these alloy elements into iron, and it is difficult to improve properties corresponding to the added amount.

Therefore, in order to efficiently bring out the effect of alloying element addition, it is conceivable to alloy the alloying element with iron in advance.
The solid solution hardening reduces the compressibility of the alloyed iron powder, making it difficult to increase the density of the green compact, which is disadvantageous for improving the durability.

The present invention has been made to solve the above-mentioned problems of the conventional iron-based valve seat material and the iron-based alloy powder used for the iron-based valve seat material.
Offers iron-based sintered alloys with improved heat and wear resistance and iron-based alloy powders for sintering with improved compressibility and corrosion resistance in response to the severe usage environment of recent valve seat materials. The purpose is to do.

[0009]

In view of the fact that when alloying an additive element with iron powder, the alloy powder is solid-solution hardened and the compressibility is reduced, the present inventors have proposed an additive element which does not form a solid solution hardening even when alloyed. Research on the composition range of As a result, it has been found that the compressibility of the alloy powder can be ensured in the specific composition range of the additive element. In addition, when the alloy powder having the specific composition range is used, the corrosion resistance and the abrasion resistance of the sintered body are improved and the corrosion resistance and the abrasion resistance of the sintered body are improved by a combination of specific additive elements. The inventors have found that the abrasion property is remarkably improved, and completed the present invention.

[0010] Furthermore, the present inventor has proposed to improve the chemical composition and alloying form of the matrix of the iron-based sintered alloy for valve seats, and the structure and wear resistance of the matrix in order to improve the properties such as wear resistance and seizure resistance. , And the infiltration material, the relationship between the infiltration rate and the abrasion resistance, seizure resistance, etc. were intensively studied. As a result, the present inventors have found the specific structure range and alloying morphology of the matrix exhibiting excellent wear resistance, and have found an infiltrated alloy.

[0011] The iron-based alloy powder for sintering having excellent compressibility and corrosion resistance according to claim 1 or 2 of the present invention contains, as alloying elements, Co: 2 to 15% by weight, Mo; 10
%, Preferably more than 3% to 10%, with the balance being unavoidable impurities and Fe.

Further, the iron-based sintered alloy having excellent wear resistance according to claim 3 or 4 of the present invention has a weight ratio of Co: 2.
To 15%, Mo; 2 to 10%, preferably more than 3% to 10%, with the balance being graphite powder 0.2 to 2.1 with respect to iron-based alloy powder consisting of unavoidable impurities and Fe. % And a molding lubricant are mixed, molded, and sintered.

[0013] Further, claim 5 or claim 6 of the present invention.
The iron-based sintered alloy having excellent seizure resistance and wear resistance is obtained by adding Pb, Cu, Pb-Cu alloy to the iron-based sintered alloy having excellent wear resistance obtained in claim 3 or 4. And 3 to 25% of an infiltration alloy made of any of alloys containing these as main components.
Is infiltrated and infiltrated and diffused into the pores and around the pores of the sintered alloy.

[0014]

The iron-based alloy powder for sintering of the present invention is an alloy powder containing Co: 2 to 15% and Mo: 2 to 10% by weight as alloying elements. The solid solution homogeneity is high, and excellent corrosion resistance, oxidation resistance and abrasion resistance can be obtained with a small amount of alloy as compared with the conventional method of mixing element powders.

Further, since the composition range of the alloying element is restricted to the above-mentioned composition range, the compressibility is less reduced, and the compressibility is slightly reduced as compared with the conventional method of mixing the element powders, but is almost the same. There is no risk of affecting oxidation resistance and corrosion resistance which are strongly related to density.

In the iron-based sintered alloy of the present invention, the sintered alloy obtained by mixing the conventional element powders has variations in Mo and Co concentrations,
Where austenite forming element has high Co concentration, it becomes austenite, and where ferrite forming element Mo is high, it becomes pearlite and has a mixed structure, which is inferior in wear resistance. However, Co and Mo are uniformly dissolved in Fe base. Therefore, the base becomes bainite and has excellent wear resistance.

Pb, C on the sintered alloy obtained in the present invention
The infiltration of u, Pb-Cu alloys and alloys containing these as main components is performed on valve seats used under severer conditions, and the infiltrated infiltrated alloy is formed on the contact portion between the valve and the valve seat. By acting as a lubricant intervening and further improving the thermal conductivity of the sintered alloy, the effect of efficiently lowering the temperature of the surface in contact with the valve seat improves the wear resistance.

If the infiltration amount of Pb, Cu, Pb-Cu alloy and alloys containing these as main components is less than 3%, the effect of infiltration cannot be exhibited, and if infiltration exceeds 25%, the skeleton becomes brittle. The infiltration range is set to 3 to 25% because there is a possibility that an adverse effect may be caused due to weakening or weakening. Suitable infiltration metals are lead, lead-copper and copper, or metal systems containing these as main components.

Next, the reason why the composition range of alloying elements and the like in the present invention is limited will be described. Co: 2 to 15% Co is dissolved in the base material to strengthen it and has an effect of improving heat resistance and corrosion resistance, but the content is 2%.
When the content is less than 15%, the effect is insufficient, and when the content exceeds 15%, the effect is further improved but the economy is lacking.
%.

Mo: 2 to 10% Mo forms a solid solution in the base material and strengthens it, and also has an effect of improving the strength in a high-temperature region. In a sintered body containing carbon, a part of carbides forms carbide. Effective for improving wear resistance. These effects are insufficient if the content is less than 2%, and if the content exceeds 10%, the effect is improved, but the compressibility of the powder is reduced.
Limited to 0%.

Since oxygen and carbon contained in the alloy powder have an effect of reducing the compressibility of the powder, it is desirable that oxygen and carbon be suppressed to 0.3% or less and carbon to 0.2% or less.

Graphite powder: 0.2 to 2.1% Graphite is dissolved in the matrix as a carbon component to strengthen the matrix, and partly forms carbide with Fe or Mo in the matrix to improve wear resistance. The effect is shown. If the addition amount is less than 0.2%, the above effect cannot be expected,
Further, if added in excess of 2.1%, the sintered alloy will be embrittled, so the added amount is limited to 0.2 to 2.1%.

The sintering temperature of the sintered alloy of the present invention is 1323 to
It is preferably 1573K. Sintering temperature is 1323
If the temperature is less than K, the sintering proceeds insufficiently and the wear resistance is insufficient. If the sintering temperature exceeds 1573K, the crystal grains become coarse, which is not preferable.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in comparison with comparative examples to clarify the features of the present invention. (Example 1) Nos. 1 to 5 and Nos. 7-11
An alloy having the composition shown in Table 1 was melted and made into an alloy powder by a spraying method.
It was a powder of 0 μm or less. In addition, No. Nos. 1 to 5 are examples of the present invention containing Co and Mo in the composition range of the present invention. Nos. 7 to 11 are comparative examples. 7 is a comparative example having a low Co content, and No. 7 is a comparative example. No. 8 is a comparative example having a low Mo content, 9 is a comparative example having a high Mo content, N
o. No. 10 is a comparative example having a large carbon content. 11 is a comparative example having a large oxygen content.

Further, in Table 1, No. Reference numeral 6 denotes an example of the present invention, which is a partial alloy powder having a Co-9 content shown in Table 1 prepared by preparing an Fe-9% Mo spray alloy and diffusing Co into the spray alloy powder, and having a particle size of 150 μm. These are:

In addition, No. 12 to 13 are comparative examples in which element powders were mixed, and commercially available pure iron powder, cobalt powder, and molybdenum powder (all having a particle size of 45 μm or less) were prepared.
After weighing these powders so as to have the composition shown in Table 1,
Mixing was performed using a V-type powder mixer.

[0027]

[Table 1]

With respect to the obtained sintering powder, the compressibility of the powder and the corrosion resistance of the sintered body were examined. The compressibility of the powder was obtained by applying a lubricant to a mold using a mold having a diameter of 11.3 mm, producing a compact at a molding pressure of 588 MPa, and measuring the density of the compact.

The corrosion resistance of the sintered body was determined to be 6.9 g / cm in density.
After the green compact of No. ³ was molded, it was kept at a temperature of 1400 K for 1800 seconds in a nitrogen atmosphere, and then cooled at 20 to 30 ° C./min to produce a sintered body as a test piece. The test piece was heated while being immersed in a mixed reagent of lead oxide and lead sulfate (1108).
K × 3.6 Ks), and the weight change after the test was determined. In addition, No. No corrosion resistance tests were performed on 10-11. The results obtained are summarized in Table 1.

As shown in Table 1, the comparative example No.
No. 7 has a low Co content of 1.2% and therefore has good compressibility, but is inferior in corrosion resistance as compared with the examples. 8 has a low Mo content of 1.3%,
Although excellent in compressibility, the corrosion resistance was inferior to that of the examples. 9 has a Mo content of 12.0
%, The loss of corrosion is small, but the compressibility is inferior to the examples. No. of the comparative example. Samples 10 to 11 were inferior in compressibility as compared with the examples because the content of oxygen or carbon was high.

In addition, N which is a comparative example using element powders
o. In Nos. 12 to 13, the diffusion of the alloy element into the base material is performed at the time of sintering, but it is difficult to completely diffuse the alloy element, and even if a large amount of the alloy element is added, a portion having a low solid solubility is generated. Corrosion oxidation occurred selectively, and the corrosion resistance was remarkably inferior to the examples. For example, in Comparative Example No. 1
2 is Example No. 2. No. 3 despite having the same composition as No. 3. While the corrosion weight loss of No. ³ was 0.727 g / cm ³ , 12 has a weight loss of 1.047 g / c.
m ³ and significantly more.

On the other hand, in the embodiment of the present invention, No.
In Nos. 1 to 6, alloying elements were pre-alloyed, so that solid solution homogenization was excellent, the effect of adding the alloying elements was maximized, and the corrosion weight loss was 0.645 to 0.832 g / cm ^3, which was small. It was confirmed that excellent corrosion resistance and oxidation resistance were obtained with the amount of alloy.

As for the compressibility of the powder, since the amount of the alloy was regulated within a predetermined range, the rate of decrease in the compressibility was low. 12 to 13 is 6.85 to 6.92 g / cm ³ , whereas the embodiment of the present invention is 6.80 to 7.02 g / cm ³ ,
It turned out that almost the same compressibility can be secured.

(Example 2) 14 to 21 and No. 14; Spray alloy powder (particle size: 177 μm or less) containing Co and Mo having the composition shown in FIGS. 24 to 26 and the balance Fe containing unavoidable impurities was prepared in advance, and graphite (Gr) having the composition shown in Table 2 was added to the spray alloy powder. ; Natural graphite, particle size 40μ
m or less) and 1.0% of zinc stearate as a lubricant were mixed with a V-type mixer.

Next, the molding pressure was adjusted so that the green compact density became 7.0 g / cm ³ , and a test piece was manufactured. Subsequently, sintering was performed at a sintering temperature (K) shown in Table 2 in a nitrogen atmosphere. In addition, No. 14-21 are examples of the present invention containing Co, Mo and graphite in the composition range of the present invention,
o. Nos. 24 to 26 are comparative examples. No. 24 is a comparative example having a low Co content; No. 25 is a comparative example having a low Mo content, 26 is a comparative example having a large Mo content.

[0036]

[Table 2]

In Table 2, No. 22 to 23 are comparative examples using element powders, and include spray iron powder, Co powder, Mo powder,
FeMo powder and graphite powder were prepared, weighed so as to have the composition shown in Table 2, mixed and molded in the same manner as above to obtain a green compact, and fired in a nitrogen atmosphere. Sintering was performed at a sintering temperature (K).

In obtaining a green compact, No. 3 was used as a comparative example. Except for Example 26, the molding pressure was 5 to 7 Ton / cm ³ in both Examples and Comparative Examples. No. 26 required a pressure of 10 Ton / cm ³ or more, and it was found that there was a problem in practicality in consideration of the mold life.

In the case of using the Fe—Co—Mo alloy powder, for example, In No. 14, Fe-3.1%
99.1% of Co-6.5% Mo powder and 0.9% of Gr powder
And a total of 100%, and further 1% of zinc stearate are added and mixed. For example, Comparative Example N
o. 22, Co powder 8%, Mo powder 6%, Gr powder 0.9
%, 85.1% of Fe powder, 100% in total, and 1% of stearic acid are added and mixed.

With respect to the sintered bodies of Examples and Comparative Examples obtained in Table 2, a wear test was performed to evaluate the wear resistance of each material. The abrasion test was performed by processing the sintered bodies of the respective examples and comparative examples into valve seat rings, and using a valve and a valve seat tester simulating actual machines. This test device heats the valve and valve seat by combustion of propane gas, and the mechanism that opens and closes the valve by driving the cam,
This is to reproduce the tapping wear state of the valve and the valve seat.

In the test, the valve material was JIS SUH3, the valve temperature was 1023K, and the valve seat temperature was 6
Control to keep at 73K, cam rotation speed 2000rpm
The operation time was 28.8 Ks, and the wear amount of the valve seat was measured. The results obtained are shown in FIG.

As shown in FIG. 1, Comparative Example No. Sample No. 22 had the largest abrasion amount of 89 μm.
Comparative Example No. The composition of Example No. 22 15 is almost the same as that of Example No. It is about three times as large as 15. This is because of the difference in hardness due to the difference in tissue,
This is considered to be due to the difference in wear resistance. That is, Example No. 1 according to the present invention. The base tissue of Comparative Example No. 15 was bainite. Since the base organization of No. 22 was mainly composed of pearlite, the apparent hardness was compared. No. 22 is Example No. 22. It is about 1/2 of 15.

Comparative Example N in which element powders were similarly mixed
o. 23 is Comparative Example No. 23. 22 FeM as hard particles
o A material to which an intermetallic compound is added, but the wear amount is 50
μm, and Comparative Example No. 22 shows that although the abrasion resistance was improved, the abrasion resistance was inferior to the examples of the present invention.

The comparative example No. No. 24 has a low Co content of 1.2%, and is a comparative example No. 24. In the case of No. 25, since the Mo content is as small as 1.3%, the wear amount is 45 to 5
2 μm, inferior in wear resistance. Also, the comparative example N
o. In No. 9, the Mo content was as large as 12.2%, and the abrasion amount was 30 μm, which was excellent in abrasion resistance. However, since the compressibility was not good as described above, the density improvement was insufficient.

On the other hand, in the embodiment of the present invention, No.
In Nos. 14 to 21, the alloy elements were solid-solution homogenized in the base structure, so that the base structure became a bainite structure, and the wear amount was 25 to
It was 35 μm, and it was found that the abrasion resistance was significantly improved.

Example 3 A spray alloy powder (particle size: 177 μm or less) of Fe, containing Co and Mo and containing unavoidable impurities shown in Table 3, and infiltration alloy powders A to C (infiltration material A; Pb , Infiltrant B; Cu-30Pb, infiltrant C;
Cu) is prepared in advance, and graphite (Gr: natural graphite powder, particle size of 40 μm or less) shown in Table 3 and a lubricant zinc stearate (1.0%) are weighed into the sprayed alloy powder, and then mixed by a V-type mixer. Powdered. Next, the molding pressure was adjusted so that the green compact density became 7.0 g / cm ³ , to produce a test piece. Subsequently, sintering was performed at 1403K in a nitrogen atmosphere.
Next, the infiltration treatment was performed under the same atmosphere and the same temperature conditions as the sintering.

[0047]

[Table 3]

In Table 3, No. 27 to 37 are examples of the present invention. No. Nos. 38 to 40 are comparative materials. No. 38 is a comparative material which did not infiltrate the infiltration material at all. No. 39 is a comparative material having a low Co content. Reference numeral 40 is a comparative material in which the infiltration amount of the infiltration material was smaller than the composition range of the present invention.

Next, abrasion tests were performed on the obtained examples and comparative materials, the abrasion resistance of each material was investigated, and the suitability as a valve seat was investigated. In the abrasion test, the obtained examples and comparative materials were used as block materials, and the mating material (rotor) was used as JIS SUH11, and the abrasion resistance was evaluated using an Ogoshi type abrasion tester under the following test conditions. The wear resistance was evaluated as a block wear mark width, and is shown in Table 3.

(Ogoshi Wear Test Conditions) Counterpart Material (Rotor) JIS SUH11 Block Material Sample No. 24-41 Sliding speed 0.51m / s Friction distance 100m Final load 31.5N Temperature Room temperature Measurement item Block wear mark width

As shown in Table 3, the infiltration amount of the infiltration material was 0
Comparative material No. 38 and the infiltration amount of the infiltration material is 2%
And comparative material No. Comparative material No. 40 has a block wear scar width as large as 2.2 to 2.3 mm and a small Co content. 39 also has 2.1 mm block wear mark width
All were inferior in wear resistance.

On the other hand, in the embodiment of the present invention, No.
Nos. 27 to 37 indicate that the infiltration material is 14% in the composition range of the present invention.
Is infiltrated, so that the infiltration material acts as a lubricant by interposing the contact portion, and the block wear mark width is 1.4 to 1.9 mm, and the wear resistance and seizure resistance are improved. It was confirmed that.

(Example 4) The alloy element is Mo; 3.3
%, Co; 6.1%, O: 0.04%, C: 0.03%
%, The balance being an iron-based alloy powder (particle size: 177 μm or less) composed of Fe and inevitable impurities was produced by a spraying method. With respect to the obtained powder for sintering, the compressibility of the powder and the corrosion resistance of the sintered body were evaluated.

The compressibility of the powder was the same as that in Example 1. A lubricant having a diameter of 11.3 mm was applied to the mold, and a compact was produced at a molding pressure of 588 MPa. Was measured. Further, the corrosion resistance of the sintered body was the same as that performed in Example 1, and the density was 6.9 g / c.
After molding a green compact of m ³ , a sintered body cooled at 20 to 30 ° C./min was manufactured as a test piece after holding at a temperature of 1400 K for 1800 seconds in a nitrogen atmosphere, and this test piece was made of lead oxide. Heating in a state of being immersed in a mixed reagent of
K × 3.6 Ks), and the weight change after the test was determined.

As a result, the compressibility of the powder was 6.98 g /
cm ³ , and showed compressibility comparable to the results in Table 1 of Example 1. In addition, the change in corrosion resistance weight of the sintered body was -0.790 g / cm ³ , and the same value was obtained by comparison with Table 1 of Example 1.

(Example 5) The alloy element is Mo; 3.2
%, Co; 8.1%, the balance being an iron-based alloy powder (particle size of 177 μm or less) composed of Fe and inevitable impurities was produced by a spraying method. 0.9% of commercially available graphite and 1.0% of a lubricant were weighed into the sprayed alloy powder, and then mixed with a V-type mixer. Next, the forming pressure was adjusted so that the green compact density became 7.0 g / cm ³ , and a test piece was manufactured. Subsequently, sintering was performed at a sintering temperature of 1403K in a nitrogen atmosphere to obtain a sintered body.

The abrasion resistance of the obtained sintered body was evaluated. The evaluation method was the same as that performed in Example 2. The sintered body was processed into a valve seat ring, and a valve simulated on an actual machine was manufactured. , Using a valve seat tester. This test device reproduces the beating wear state of the valve and the valve seat by a mechanism that heats the valve and the valve seat by burning propane gas and opens and closes the valve by driving a cam.

In the test, the valve material was set to JIS SUH3, the valve temperature was set to 1023K, and the valve seat temperature was set to 6
Control to keep at 73K, cam rotation speed 2000rpm
The operation time was 28.8 Ks, and the wear amount of the valve seat was measured. The amount of wear in this example was 29 μm, and almost the same results were obtained as compared with the figure showing the amount of wear in FIG. 1 obtained in Example 2.

[0059]

The iron-based alloy powder for sintering of the present invention has a weight ratio of Co: 2 to 15% and Mo: 2 to 10% as alloying elements.
, And the balance consists of unavoidable impurities and Fe. The iron-based sintered alloy has a graphite powder of 0.2 to
2. It is characterized by being obtained by mixing 2.1% with a molding lubricant, molding and sintering, and has a high degree of solid solution uniformity of the alloying element in the base material, and the conventional mixing element powder. Excellent corrosion resistance, oxidation resistance and abrasion resistance can be obtained with a small amount of alloy as compared with the method. Since the composition range of the alloying element is regulated to the above composition range, the compressibility is less reduced,
Compared with the conventional method of mixing the element powders, the compressibility is slightly reduced, but the compressibility is almost the same, and there is no possibility of affecting the oxidation resistance and the corrosion resistance which are strongly related to the density. Also,
Since Co and Mo are uniformly dissolved in the Fe matrix, the matrix becomes bainite and has excellent wear resistance. The infiltration of the sintered alloy obtained in the present invention with Pb, Cu, a Pb-Cu alloy and an alloy containing these as main components acts as a lubricant through a contact portion between the valve and the valve seat. Further, by improving the thermal conductivity of the sintered alloy, the effect of efficiently lowering the temperature of the surface in contact with the valve seat is improved, thereby improving the wear resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing the wear amount of an example of the present invention and a comparative example in a wear test.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Okajima 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-48-102707 (JP, A) JP-A-56-41353 (JP, A) JP-A-62-202046 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 1/04-1/05 C22C 33/02 C22C 38/00-38 / 60 B22F 1/00-9/08

Claims (6)

(57) [Claims] 1. An alloying element containing Co in a weight ratio of 2-1.
An iron-based alloy powder for sintering having excellent compressibility and corrosion resistance, containing 5%, Mo; 2 to 10%, and the balance being unavoidable impurities and Fe. 2. The iron-based alloy powder for sintering according to claim 1, wherein Mo is over 3% to 10%. 3. Co: 2 to 15% by weight, Mo: 2 by weight ratio.
To be obtained by mixing, molding and sintering a graphite powder in a proportion of 0.2 to 2.1% and a molding lubricant with respect to an iron-based alloy powder containing 10 to 10%, with the balance being unavoidable impurities and Fe. An iron-based sintered alloy with excellent wear resistance. 4. The iron-based sintered alloy having excellent wear resistance according to claim 3, wherein Mo is more than 3% to 10%. 5. A weight ratio of Co: 2 to 15%, Mo: 2 to 5%.
The iron-based alloy powder containing 10%, the balance being unavoidable impurities and Fe, is mixed with 0.2 to 2.1% of graphite powder and a molding lubricant, molded and sintered, and then Pb, Cu, P
The sintered alloy is infiltrated with 3 to 25% of an infiltrated alloy made of any of a b-Cu alloy and an alloy containing these as a main component, and melted around the pores and around the pores of the sintered alloy. An iron-based sintered alloy with excellent wear and seizure resistance characterized by being immersed and diffused. 6. The iron-based sintered alloy according to claim 5, wherein Mo is over 3% to 10%.