JP3230903B2 - Heat resistant aluminum powder metal alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant aluminum powder
Related to metallurgical alloys.

[0002]

2. Description of the Related Art Parts used in internal combustion engines such as automobiles and motorcycles, such as pistons, connecting rods and brake rotors, must be strong enough to withstand severe movements at high temperatures. On the other hand, in recent years, weight reduction of parts has been desired from the viewpoint of weight reduction of automobiles and the like and energy saving. For this reason, aluminum alloys have come to be used for parts requiring the high-temperature strength. As an aluminum alloy excellent in such high temperature strength,
Research and development of a powder alloy in which a rapidly solidified powder of an Al-Fe alloy containing Fe in supersaturation is joined and integrated by hot plastic working. For example, JP-A-62-47
No. 448 discloses a hot extruded material of a heat-resistant aluminum alloy powder containing 10% by weight or more of Fe in supersaturation.

[0003]

However, since an oxide film is formed on the surface of the Al alloy powder, in order to integrate such powder, the oxide film on the powder surface is divided and crushed to integrate the bases. Need to be For this reason, a high-output hot extruder is required, and in the case of hot forging (hot uniaxial compression), it is necessary to increase the working ratio. In addition, when hot pressing is performed with a small working ratio by hot forging or hot isostatic pressing, the heating temperature is set near the melting point in order to strongly join and integrate the powders. However, the properties originally possessed by the rapidly solidified powder are impaired, and the material is deteriorated.

[0004] The present invention has been made in view of such problems, and an object is to provide a powder with each other easily joined integrated strength and moldability is improved heat aluminum powder metallurgy alloy.

[0005]

According to the present invention, there is provided a heat-resistant aluminum powder metallurgy alloy comprising an Al-Fe alloy containing Fe in a supersaturated state.
20-50 watts of fine Ni powder to rapidly solidified powder of alloy
heat-resistant aluminum powder metallurgy obtained by joining and mixing the mixed powder containing t% in the solid phase temperature range of the Al-Fe alloy.
In a gold alloy, Al is added to the boundary of the Al-Fe alloy powder.
Heat aluminum powder metallurgy alloy, characterized in that -Ni phase is formed.

[0006]

When a mixed powder of 20-50 wt% of a quenched alloy powder of an Al-Fe alloy containing supersaturated Fe and a fine Ni powder is hot-worked in a solid phase temperature range, an Al-Fe alloy is obtained.
The alloy powder diffuses into the Ni powder, and an Al-Ni phase is formed at the boundary between the Al-Fe alloy powder and the Ni powder.
Since the powders are bonded to each other via the Ni phase, the bondability is improved, and as a result, the strength of the powder metallurgy alloy is also improved.
Therefore, there is no need for processing with a strength that breaks or crushes the oxide film formed on the powder surface, and the powders can be easily joined to each other even at a relatively low temperature and mild hot working with a small amount of plastic deformation. Can be integrated.

The reason why the hot working is performed in the solidus temperature range of the Al-Fe alloy powder is that, when the temperature exceeds the solidus temperature range of the Al-Fe alloy powder, the liquid phase and Ni undergo a melting reaction. For example, in an Al—Fe alloy containing Fe of 38 wt% or less, a liquid phase is formed at a temperature exceeding 630 ° C., and the diffusion of Al into Ni and the diffusion of Ni into Al progress, but cracks are apt to occur during cooling. Because it becomes.

[0008]

The Al-Fe alloy powder used as the raw material of the present invention is
The raw material alloy is melted at a temperature of about 50 to 200 ° C. higher than its melting point, and quenched at a cooling rate of about 10 ³ to 10 ⁶ ° C./sec by water or an appropriate powder manufacturing method such as a gas atomization method or a rotating water flow method. can get. Such rapid cooling, the Al-Fe alloy powder, theta-FeAl ₃
Is finely dispersed to obtain an Al-Fe alloy powder. The rotating water flow method is, as disclosed in Japanese Patent Application Laid-Open No. 4-17605, to form a cooling water layer that flows down while rotating on the inner peripheral surface of a cooling cylinder, and the molten metal flows into the cooling water layer. Is obtained by supplying a jet of water, separating the jet by a swirling cooling liquid layer, and rapidly solidifying it to obtain a metal powder. According to this production method, a cooling rate of 10 ⁵ ° C / sec or more can be easily obtained even with relatively large particles having an average particle size of 200 µm.

As the Al-Fe alloy powder used as a raw material of the present invention, an appropriate high-temperature and high-strength Al-Fe alloy powder such as that disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 62-47448 may be used. Can be. Preferably, the tensile strength after integrated by hot working is 20 kgf at 300 ° C.
/ Mm ² or more. Next, the Al-Fe alloy powder and the Ni powder are blended. The blending amount is preferably about 20 to 50% by weight of the latter powder with respect to the former alloy powder. If it is less than 20%, the bonding promoting effect of Ni powder is insufficient,
On the other hand, if it exceeds 50%, weight reduction will be impaired.
The particle size of the powder is not particularly limited, but usually, an Al-Fe alloy powder of 590 µm or less and a Ni powder of 10 µm or less are used. In order to improve wear resistance, SiC, A
A hard ceramic powder such as l ₂ O ₃ may be appropriately added to the mixed powder.

[0010] integrally joined to the mixed powder, a molding method, hot extrusion, hot forging, it is possible to apply the appropriate hot working means hot isostatic pressurization. In the present invention, N
An i-powder produces an Al-Ni phase, and the powders are bonded to each other via this phase. Therefore, strong processing conditions are not required, and a high-power extruder is not required. Even in the case of hot pressing, it can be processed at a relatively low temperature and a low degree of processing. In addition, when the material is subjected to hot working, it may be preliminarily formed by cold compression in consideration of handleability of the raw material powder.

Next, specific examples for obtaining the heat-resistant Al powder metallurgy alloy of the present invention will be described. (1) An Al-18 wt% Fe alloy powder was produced by a rotating water flow method. The average particle size of the powder is 200 μm. (2) The Al—Fe alloy powder and Ni powder (average particle size 5 μm)
m) and 30% by weight of Ni powder and uniformly mixed, and then the mixed powder was heated at 570 ° C. and 760 MPa.
To give a compact (Example) having an outer diameter of 64 mm. The relative density of this compact was 99.9.
%Met. As a conventional example, a compact was manufactured under the same conditions using only the Al alloy powder. (3) Bending test specimens were collected from these compacts, and the bending strength from room temperature to 500 ° C. was measured. In addition, the same test piece was sampled from FC25 material for comparison, and this was also subjected to a bending test. The result is shown in FIG. In the figure, A is an embodiment, B is a conventional example, and C is FC25. From FIG.
Compared with the conventional example, the embodiment has significantly improved room-temperature strength and high-temperature strength, and it can be seen that there is no inferiority to FC25. (4) As a result of EPMA analysis using the compact after hot pressing, Ni ₂ Al ₃ was identified. This Al-Ni
The phase is assumed to be an Al diffusion layer formed at the boundary of the Ni powder. Furthermore, after 2hr maintained at 570 ° C. in the molded body subjected to a heat treatment furnace cooling, where by using the obtained sample was EPMA analysis, in addition to the _{Ni 2 Al 3, NiAl 3,} F
eNiAl ₉ was identified. On the other hand, although Al-Fe alloy powder was recognized, Ni powder was not recognized. From this, it is presumed that the Ni powder portion was replaced with Ni ₂ Al ₃ and NiAl ₃ .

[0012]

As described above, the heat-resistant aluminum powder metallurgy alloy of the present invention has an Al—
20 to 5 fine Ni powder compared to rapidly solidified powder of Fe alloy
Heat-resistant aluminum powder obtained by joining and mixing a mixed powder containing 0 wt% in the solid phase temperature range of the Al-Fe alloy
In the metallurgical alloy, the specific amount of the Al-Fe alloy powder
Via the Al-Ni phase formed at the boundary between the powder and the Ni powder
Powders can be easily joined together, resulting in the present invention
The heat-resistant aluminum powder metallurgy alloy has improved strength. Obedience
Thus, the oxide film formed on the powder surface as in the past was separated.
No need for high strength processing such as breaking or crushing.
Even with mild hot working with little plastic deformation at high temperatures,
The raw material powders can be easily joined and integrated.

[Brief description of the drawings]

FIG. 1 is a graph showing the bending strength of Example A, Conventional Example B and plain cast iron C at various test temperatures.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-47449 (JP, A) JP-A-3-68723 (JP, A) JP-A-52-46316 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) C22C 21/00-21/18 C22C 1/04

Claims (1)

(57) [Claims] 1. 20 to 50% by weight of fine Ni powder with respect to a rapidly solidified powder of an Al—Fe alloy containing Fe in supersaturation.
In a heat-resistant aluminum powder metallurgy alloy obtained by joining and mixing the mixed powder in the solid-state temperature range of the Al-Fe alloy, an Al-Ni phase is formed at a boundary of the Al-Fe alloy powder. Formed
Heat aluminum powder metallurgy case <br/> alloy, characterized by being.