JPH03126826A - Production of formed body of silicide-type intermetallic compound - Google Patents

Abstract

PURPOSE:To produce a formed body of silicide-type intermetallic compound having superior formability by mixing a metal element powder and an Si powder, filling a metallic vessel having superior workability with the resulting powder mixture, exerting vacuum deaeration, sealing the vessel, and carrying out forming by means of hot extrusion at an alloying reaction temp. or above. CONSTITUTION:A powder of metal element (Ni, Fe, or combination of Ni and Fe) forming a silicide-type intermetallic compound with Si and an Si powder are mixed, and a metallic vessel 2 (soft steel, stainless steel, etc.) having superior workability is filled with the resulting powder mixture 1 (in which grain sizes of both powders are regulated to <= about 150mu respectively). At this time, it is desirable to regulate the wall thickness of the vessel 2 to about 1-4mm, and also it is preferable to regulate the relative density of the filling powder 1 to >= about 40%. Subsequently, the above vessel is heated up to a temp. between the ordinary temp. and about 500 deg.C and evacuated to >= about 1X10<-1>mmHg and a vent hole 3 is sealed, and then, the vessel 2 is hot-extruded at a temp. of the alloying reaction temp. of both metals or above and formed into the prescribed shape. By this method, a superior bar-shaped body consisting of the silicide-type intermetallic compound can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a silicide-based intermetallic compound molded body, and in particular to a method for manufacturing a silicide-based intermetallic compound molded body, such as a tubular body or a rod-shaped body, which is generally difficult to mold. The present invention relates to a method for producing a molded article.

(Prior Art) It has been known that intermetallic compounds have excellent properties. For example, TiM has excellent high temperature strength,
Although N1tSi is widely known to have excellent corrosion resistance, it has poor malleability at room and high temperatures, making it difficult to mold using conventional processing techniques. In particular, silicide-based intermetallic compounds, that is, N
t:+Si, Pe5Si has very poor hot deformability;
When ingot lumber is hot extruded, it may break into small pieces or
It was difficult to obtain a good molded product due to the occurrence of a large rank.

As a means to solve this problem, for example, "Plasticity and Processing J.
Vol. 23, Na260 (1982-9) proposes a lateral pressure extrusion processing method. This is Ti-3
This is an attempt to mold a difficult-to-process material using a special extrusion method, such as extruding a 7wt% AQ alloy member while applying lateral pressure, but it has not yet been fully put into practical use.

Furthermore, as another means, Japanese Patent Application Laid-open No. 63-247321 proposes a method for forming a Ti-AQ gold intermetallic compound using a powder metallurgy method.

(Problems to be Solved by the Invention) However, there has been no report on the method for forming the silicide-based intermetallic compound itself, and it has not been considered to be an object of forming in the past.

As mentioned above, silicide-based intermetallic compounds have excellent functions and properties, and are expected to be used as thermoelectric materials.In addition, they also have excellent properties as structural materials, such as super corrosion resistance. is known and is expected to be put to practical use.However, it is generally difficult to mold ingots, so it has not yet been widely put into practical use as a structural material.

A general object of the present invention is to provide a simple method for forming a silicide-based intermetallic compound.

Further, a more specific object of the present invention is to provide a pipe/rod-like body at least partially composed of a silicide-based intermetallic compound, and a pipe/rod-shaped body that is at least partially composed of a silicide-based intermetallic compound, more easily than the above-mentioned prior art. It is an object of the present invention to provide a method for manufacturing a tube/rod-shaped body containing the present invention.

(Means for Solving the Problem) In order to achieve the above object, the present inventors conducted research on a method for manufacturing an intermetallic compound molded product more easily, and found that although molding is difficult with ingot material, , got the idea that there are many difficult-to-process materials that can be molded using metal powder, and first of all, whether it is possible to form a compound by such a method in the first place, and even if it is possible, it is difficult to mold it into the desired shape. We have repeatedly considered these points to see if it is possible. As a result, in the case of silicide-based intermetallic compounds, good formability can be achieved by uniformly mixing the constituent element powders of the intermetallic compound in advance, heating this to a temperature higher than the alloying reaction temperature, and then hot extrusion molding. The present inventors have discovered that an intermetallic compound molded article or a molded article containing an intermetallic compound can be obtained, and have completed the present invention.

Here, the present invention mixes a metal element powder constituting Si and a silicide-based intermetallic compound with Si powder, fills the obtained powder mixture into a metal container with good workability, and after filling is completed. , a silicide system characterized in that the metal container is sealed after vacuum degassing, and the metal container is hot extruded and formed into a predetermined shape at a temperature higher than the alloying reaction temperature of both metals. This is a method for producing an intermetallic compound molded body.

In addition, when mixing the Si powder and the constituent metal element powder of the intermetallic compound, the uniform mixing time is controlled by a mechanical alloying method in a non-oxidizing atmosphere, and the alloying reaction temperature of the two metals is adjusted. Note that such a mechanical alloying method is also effective in improving the filling rate.

(Operation) The configuration of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory diagram of a powder filling operation when molding a rod-shaped body according to the present invention.

For example, a powder mixture l obtained by mixing target metal powders such as Xi and Si1 or Fe and SI in a predetermined ratio is filled into a metal container 2 with good workability, and then the inside of the container is preferably heated. After evacuating and achieving a certain degree of vacuum, the deaeration port 3 is sealed. The powder mixture thus prepared is then heated to a predetermined temperature and then extruded into a billet for extrusion molding.

FIG. 2 shows the case of forming a tubular body, in which the powder mixture 4 is filled into the annular space of a metal container 5 containing a double cylindrical body. In this case as well, the inside of the container is depressurized and the deaeration port 6 is sealed, as in the case of FIG. 1, to form a billet for extrusion molding.

The extrusion-forming billet thus prepared is then formed into a tube or rod-like body of a predetermined shape by conventional extrusion molding.

Hereinafter, the processing steps in the present invention will be explained in order.

The constituent metal elements that form a silicide-based intermetallic compound with Si are Ni and Fe, or a combination thereof. Therefore, these and si! 5) Appropriate proportion of the end and end, for example, 8 for old zSi system
~16i+t%Si: Blend and mix at a ratio of 92 to 84wt%Ni.

The particle size of the Si powder and the constituent element powder of the intermetallic compound used in the present invention is preferably 150 μm or less. This is to lower the alloying reaction temperature and to make the composition uniform.

The metal powder thus prepared is filled into a metal container with good workability.

Here, metal containers with good workability include mild steel, low carbon steel, stainless steel, and Ni-based alloy C example: A11oy62
5) A metal with good malleability at hot extrusion temperature or a metal with good malleability at hot extrusion temperature, and
The wall thickness of the container is 1 to 4111 mm, which is a metal with high hot deformation resistance.
1 is desirable. This is because during hot extrusion molding, contact between the die and the mandrel occurs in the metal container, and the hot malleability of the metal container affects the formability of the extruded product.

It is preferable that the relative density of the packed powder at the time of filling the powder into the metal container is 40% or more. Filled powder relative density is 4
This is because if it is less than 0%, buckling may occur in the hot extrusion molded product and a good molded product may not be obtained.

The powders of the constituent elements of each intermetallic compound may be simply blended uniformly, but in some cases, the distance between the eyebrows may be reduced in advance at this blending stage to facilitate the formation of intermetallic compounds. Yes, this is what is called a mechanical alloying method.

Such a mechanical alloying method uses a ball mill, a vibratory robot, an attritor, etc. to crush the metallic Si powder and the constituent metal element powder of the intermetallic compound, mix them uniformly in a predetermined ratio, and cause the powder surface diffusion. This has the advantage of increasing the powder packing density and lowering the alloying reaction temperature, which is lower than the heating temperature before hot extrusion. In order to prevent oxidation and nitridation of the surface of the mixed powder, this mechanical alloying treatment is performed in a vacuum with a vacuum level of I It may also be possible to prevent a decrease in ductility.

In the case of silicide-based intermetallic compounds, the alloying reaction initiation temperature of each element is ＼'940'C for Ni and Si-based compounds.
, Fe5Si type is V105Q''c, and by performing the above-mentioned mechanical alloying, the alloying reaction start temperature can be mathematically lowered by several hundred degrees.

After filling the powder mixture, the metal container is vacuum degassed prior to extrusion molding.
It is desirable to hold the powder at a vacuum level of 10 to 10 mmHg or more for 10 minutes or more, in order to efficiently remove adsorbed gas and water on the powder surface, thereby improving the quality of the product. In addition, it is necessary to perform the sealing in a vacuum state to avoid air intrusion into the pores in the filling powder. The heating temperature before hot extrusion is set to be above the alloying reaction temperature and below the solidus temperature.

This is done in order to cause the element content to diffuse before the hot extrusion process and to obtain a good extruded product by utilizing the compositional flow caused by the fine graining of the powder, and also because large segregation occurs when the temperature exceeds the solidus temperature. This is to avoid an extreme drop in moldability.

The hot extrusion temperature is equal to or 10% higher than the heating temperature.
A temperature lower than 0°C is desirable. This is because when the temperature drop is large, the hot deformation resistance increases significantly, making extrusion molding difficult.
This is because a density close to the true density cannot be obtained.

Hot extrusion may be carried out by conventional means, and in that case, the extrusion ratio is preferably 4 or more in order to ensure cold ductility. In addition, in the case of Ni and Si systems, the heating temperature is 1
The temperature is preferably 100°C or less. Also, what is the molding temperature? 000℃
The above is preferable.

(Example) The present invention will be specifically explained with reference to Examples.

Example 1 Particle size 74 JJI ungrooved Si powder 13 wt% and particle size 4 to 7
The powder mixture l obtained by mixing 87 wt% of N1FA powder of μ in a ball mill in an Ar gas atmosphere for 0 = 18 hr.
After filling the container 2 made of 5US304 stainless steel with a thickness of 3II11 shown in Fig. 1 through the degassing port 3 to a relative density of 40 to 52%, the degassing port was evacuated and heated at 400°C for 1 hr. After degassing with 10-~-〇g, seal it. After heating this 5US304 steel container to 900-1150'C, it was immediately heated to 850-1100C using a Eugene hot extruder.
Extrusion molding was performed at 00° C. to create a rod-shaped body containing a silicide-based intermetallic compound accounting for 80% by volume. The moldability of the obtained rod-shaped body was evaluated.

The results are summarized as sample Nal~4 along with the molding conditions.
In the same table, an example of production of ingot material is also shown as sample N[L7 as a conventional example.

Example 2 St powder 1 with particle size less than 10μ and less than 74μ, respectively
1-(% and Ni1I with particle size 4-7μ and less than 74mm)
) and 89-1% powder were mixed for 0 to 30 mtn in an Ar gas atmosphere attrike, and the obtained powder mixture 4 was poured into a 5S34 mild steel volume H5 with a thickness of 21111 as shown in Fig. 2 through a degassing port 6. After filling, vacuum is drawn from the degassing port 6 to 300"
After heating with CXIhr, it was degassed with IXIP"mdg and then sealed.

After heating this 5S34 mild steel container to 1100°C, it was immediately extruded at 1050°C using a Eugene hot extruder to create a tubular body containing a silicide-based intermetallic compound that accounted for 60% by volume. The moldability at this time was evaluated.The results are shown in Table 1 as sample weight 5.6 along with the manufacturing conditions.

Example 3 14.4 wt% S+ powder with particle size less than 53p and particle size 149
85.6 wt% of Fe powder is mixed with 85.6 wt% of Fe powder in an Ar gas atmosphere for 18 hours, and the obtained powder mixture 4 is placed in a 5534 soft steel container 5 with 2 openings shown in Fig. 2 with a degassing port. After filling from No. 6, vacuum is drawn from degassing port No. 6, and 400
'CX1hr while heating I X 10-'mmt1
After degassing with g, the container was sealed. This 5S34 mild steel container is 11
After heating to 50"C, extrusion tube production is immediately performed at 1100°C using a Eugene hot extruder, and the volume ratio is 95%.
A tubular body of a silicide-based intermetallic compound containing Fe3Si was prepared, and its formability was evaluated. The results are shown in Table 2 as sample Nα1 along with the manufacturing conditions. In the same table, an example of production of ingot lumber is shown as sample 2 as a conventional example.

Table 2 (Effects of the Invention) As explained above, since the present invention is fl-shaped, it is possible to manufacture tubular bodies and rod-shaped bodies with good moldability of silicide-based intermetallic compounds, which were extremely difficult to mold in the past. This makes it possible to achieve this, which is extremely useful industrially.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic longitudinal cross-sectional views illustrating the formability of the silicide-based intermetallic compound powder billet used in the present invention. 1: Ni and Si powder mixture 2 Stainless steel container 3: Deaeration hole 4: Ni and Si powder mixture or Pa and St powder mixture 5: Mild steel container 6: Deaeration hole Application location Sumitomo Metal Industries, Ltd. Co., Ltd.

Claims (4)

[Claims] (1) Mix Si powder with metal element powder constituting Si and silicide-based intermetallic compounds, fill the resulting powder mixture into a metal container with good workability, and after filling, vacuum degas After that, the metal container is sealed, and the metal container is hot-extruded to form a predetermined shape at a temperature higher than the alloying reaction temperature of both metals. How the body is manufactured. (2) When mixing the Si powder and the constituent metal element powder of the intermetallic compound, the mixture is homogenized by a mechanical alloying method in a non-oxidizing atmosphere, and the alloying reaction temperature is adjusted. A method for producing a silicide-based intermetallic compound molded body. (3) The relative density of the powder packed into the metal container is 40%.
The method for producing a silicide-based intermetallic compound molded body according to claim 1 or 2, wherein the method is as follows. (4) The method for producing a silicide-based intermetallic compound molded body according to claim 1, 2 or 3, wherein the metal container is made of low carbon steel, stainless steel or Ni-based alloy.