JPS5920723B2 - Method for producing dispersion-strengthened metal powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing metal powder in which non-metal powder particles suitable for use in producing a dispersion-strengthened sintered alloy are dispersed.

For example, so-called dispersion-strengthened metals (including alloys in this specification) in which oxide particles such as Al2O3 are dispersed in Al metal have excellent high-temperature strength and are used for jet engine turbine disks or turbine blades. It is used.

It is extremely difficult to manufacture alloys in which nonmetallic particles are uniformly dispersed in this way using the usual melting and casting method.
It is easily understood that powder metallurgy is most suitable for its production.

By the way, in dispersion-strengthened sintered alloys in which non-metallic particles such as metal oxides and nitrogen oxides are dispersed in metal, the particle size and blending ratio of the metal powder or non-metal powder as the raw material powder must be sufficiently adjusted. If proper care is not taken, even if the blended powder is thoroughly mixed, non-metallic powder particles will be unevenly distributed between the metal particles of the sintered alloy base, and for example, in a creep test, it will be difficult to detect cracks from this area. This often has negative effects such as lowering the

FIG. 1 is an optical micrograph (magnification: 500 times) showing such a metal structure, and it is clearly observed that non-metallic particles appearing in black are unevenly distributed at the boundaries between metal powder particles.

The present invention solves the above-mentioned problems and provides a method for producing raw material powder that can easily obtain a dispersion-strengthened sintered alloy having a structure in which nonmetallic particles are uniformly dispersed in a metal base. In this method of manufacturing dispersion-strengthened metal powder, in which non-metal particles are dispersed within a base of metal powder, pre-produced metal powder and non-metal powder are blended in a predetermined ratio, mixed and sintered to create a rod-like shape. A sintered body is rotatably provided as an anode, and a non-consumable electrode provided opposite to the sintered body so as to be able to move forward and backward is used as a cathode, and a voltage is applied between the two electrodes in a non-oxidizing atmosphere to generate an arc. The present invention relates to a method for producing dispersion-strengthened metal powder, which is characterized by sequentially melting and scattering a sintered body of an anode while rotating it to form a powder.

Conventionally, the atomization method has been commonly used as a raw material powder manufacturing method for dispersion-strengthened sintered alloys, and in this method, a specified nonmetallic powder is supplied to a nozzle that atomizes molten metal using gas or water pressure. The molten metal that incorporates the non-metal powder becomes atomized and solidifies, so if this raw material powder is used, the dispersibility of the non-metal powder particles may be impaired, or the particle size structure etc. may change during mixing. However, it is difficult to strictly control the blending ratio of non-metallic powder, the shape of the powder is irregular and the moldability is poor, or the equipment becomes large, so it is difficult to maintain it in a non-oxidizing atmosphere. As a result, it is difficult to produce powder of easily reactive metals such as Ti, Zr, or A1.

The method of the present application is different from the conventional method as described above, in that metal powder and non-metal powder prepared in advance are mixed in the required ratio,
The rod-shaped sintered body mixed, formed, and sintered as usual is used as the rotating electrode of a known rotating electrode type powdering device, and while rotating in a non-oxidizing atmosphere, it is sequentially remelted from the tip by an arc and scattered by centrifugal force. The sintered body for electrodes is produced by a conventional method, which is a method of obtaining spherical powder.

The raw material powder for the bulk is metal powder, which is 1.
Finer than 00 mesh (150μm), non-metallic powder is 2
Preferably, the mesh is finer than 50 meshes (65 μm).

There are no restrictions on the type of non-metallic powder, including oxides, nitrogen,
The method of the present invention can be applied to any required carbide or intermetallic compound.

In the method of the present invention, a rod-shaped sintered body for electrodes manufactured by blending and sintering metal powder and non-metallic powder is remelted and made into powder, so that in the sintered body for electrodes, raw metal powder and non-metallic powder are mixed. Even if the metal powder and the non-metal powder particles are not uniformly dispersed and mixed due to differences in specific gravity or particle size, the final sintered alloy will have the non-metal powder particles uniformly dispersed in the matrix to a satisfactory degree. is obtained.

The rotating electrode type pulverization device used in the present invention has a rotating electrode in a sealed container and an electrode that can move forward and backward in opposition to the rotating electrode, and is equipped with a gas suction device or an inert gas supply device in the container. Any known device may be used.

Since the container of the rotating electrode powdering device can be made small, the atmosphere inside the container can be arbitrarily adjusted during powder production, and powders of highly reactive metals such as Ti, Zr, and A7 can also be produced. This is convenient because the particle size of the powder can also be adjusted by adjusting the rotation speed of the electrode.

Next, an example will be described.

Ni powder (99.5% Ni, 0.08 coefficient C,
0.18%Mn, 0.18%Si, 0.2%Fe
, 0.005% S, 0.13% Cu) and TiC powder (-
400 mesh) was blended in a weight ratio of 100:5, thoroughly stirred and mixed, and then molded under a molding pressure C2 of 3t/d.
It was formed into a 5 mm round x 100 mm long, pre-sintered at 600°C x 60 minutes, and then heated and sintered at 1200°C x 60 minutes in a vacuum of IQmm mercury column.

This sintered body was machined into a 21 mm round shape and used as a rotating anode for a rotating electrode type powdering device.
While rotating at a high speed of 000 r, p, m, a DC voltage of 60 volts was applied between two tungsten cathodes placed opposite each other so that they could move forward and backward, and a current of 200 to 100 amperes was passed to generate an arc. The heat sequentially melted the tip of the anode sintered body, which was dispersed by centrifugal force and turned into powder.

The shape of the obtained powder is spherical, and the particle size is 100-15
0 mesh (150-105 microns) is approximately 75%
Met.

Figure 2A is a photograph showing a backscattered electron image (500x magnification) of the obtained Ni powder particles taken by an X-ray microanalyzer, and Figure 2B is a copy of Figure 2A, showing the distribution of TiC in an easy-to-understand manner. It is.

These figures show the Ni obtained by the method of the present invention.
It can be seen that TiC fine particles are almost uniformly dispersed in the powder particles.

Therefore, the sintered alloy obtained by forming and sintering the metal powder obtained by the method of the present invention using the raw material powder is different from the conventional dispersion-strengthened type in which metal powder and non-metal powder are mechanically mixed, formed, and sintered. Unlike alloys, non-metallic particles are dispersed inside metal particles, so it is easy to infer that this is an excellent heat-resistant sintered alloy that does not reduce creep strength.

As described above, according to the method of the present invention, a sintered body in which the required metal and non-metal powders are mixed in advance in a predetermined ratio, formed, and sintered is remelted by a rotating electrode type powdering device and powdered. Therefore, it is possible to obtain a powder in which non-metal powder particles are more uniformly dispersed in metal powder particles.

Therefore, the dispersion-strengthened sintered alloy obtained by molding and sintering this powder as a raw material powder has nonmetallic particles uniformly dispersed therein, so it is similar to that seen in dispersion-strengthened sintered alloys obtained by conventional methods. It is possible to obtain mechanical parts with no defects, high strength at high temperatures, and excellent dimensional accuracy, and the practical effects thereof are extremely large.

[Brief explanation of drawings]

Figure 1 shows Yingi standard heat-resistant alloy 100 manufactured by the conventional method.
Figure 2A is an optical micrograph (500x magnification) showing the metal structure of a sintered alloy using the metal powder of the present invention. Photograph shown (500x magnification), 2nd
Figure B is a copy of the distribution of TiC in Figure 2A.

Claims (1)

[Scope of Claims] 1. A method for producing dispersion-strengthened metal powder in which non-metal particles are dispersed in a base of metal powder, which involves blending and mixing pre-produced metal powder and non-metal powder in a desired ratio and then firing. A rod-shaped sintered body is rotatably installed as an anode, and a non-consumable electrode opposite the rod that can be moved forward and backward is used as a cathode.A voltage is applied between the two electrodes in a non-oxidizing atmosphere to generate an arc. The sintered body of the anode is sequentially melted while rotating.
A method for producing dispersion-strengthened metal powder, which is characterized by scattering and pulverizing.