JPH0433782A - Manufacture of composite material made of intermetallic compound partly at least - Google Patents

Abstract

PURPOSE:To obtain a fine joint by subjecting one member and the other member to heat treatment in a state with these members brought into contact with each other and utilizing self-generation of heat generated at the time of forming the intermetallic compound. CONSTITUTION:Both members which are worked into a desired shape are heated up to the temperature in which the metallic compound is formed. Diffusion or self-burning and sintering are generated by this heat treatment and the one member is joined to the other member by generation of heat or heat of reaction of self-burning at the time of forming the metallic compound. A mechanism of joining is carried out by force among molecules or metallic bonding force and diffusion due to the fact that the joint interface is softened or a part thereof is molten and an oxide film of the joint interface is destroyed or fine unevenness of the interface is crushed and both are completely stuck to each other by self-generation of heat at the time of forming the intermetallic compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a composite material, at least a part of which is composed of an intermetallic compound, and which is used for various purposes.

``Conventional technology'' Intermetallic compounds are used in a variety of applications because they have excellent properties such as excellent heat resistance, oxidation resistance, and abrasion resistance, can be constructed lightweight, and have functional properties such as superconductivity. It is considered to be extremely promising as a material.

Examples of intermetallic compounds include Ti-Al system, Ni-Al
system, Ni-Tl system, Co-Tl system, Fe-Al system, No-Al system.

2 such as Mo-8i system, Nb-Al system, Ti-3i system, etc.
Multi-component systems such as elemental systems, Fe-Al-9i systems, and Al-Ga-As systems are known. Specifically, as a structural material,
TiAl, Tis At.

Al3Ti, Co3Ti, Ni3Al, NiA
l, FeAl, MO3Alg.

MoSi2. Nbi A1. Ti5Siq and the like are known. In addition, T1Ni, Cu, which has a shape memory effect
Zn, etc., Nbs Sn, V3 G as superconducting materials
a, Nbs Ga, Nb3Ge, etc., magnetic materials such as Pea (AISi), 5IICO5, semiconductors and other functional materials such as InSb, GaAs, B
There are many others such as i2Te3°Zn5e.

Examples of products that utilize intermetallic compounds include external wall materials that are used at high temperatures, turbine components, engine parts such as pistons and valve systems, elastic components, and superconductors that exhibit the unique properties of various intermetallic compounds. Functional parts that take advantage of this can be considered.

[Problems to be solved by the invention] Although intermetallic compounds have excellent properties as described above,
Difficult to join. For example, when joining one member made of an intermetallic compound to another member by electron beam welding, coarsening of crystal grains may occur in the welded part, or
Welding defects that are too large to be ignored in practice may occur, and it has not been possible to control the structure, defects, etc. of the joint.

Bonding using brazing or adhesives can be considered, but the heat resistance, mechanical properties, and inherent functionality of the bonded parts are inferior to that of the base material, so it is not possible to take advantage of the excellent properties of the intermetallic compound that is the base material. .

It is also possible to join at a high temperature by heating the joint while applying pressure, but if the joint is heated to a temperature at which it becomes soft, it becomes difficult to maintain a predetermined shape.

Therefore, an object of the present invention is to be able to join composite materials in which at least one side is an intermetallic compound with high quality and at low cost, to require relatively low heating temperatures during joining, and to enable the joint to exhibit performance equivalent to that of the base material. It is an object of the present invention to provide a method for manufacturing a composite material in which the structure, defects, etc. of the joints are controlled.

[Means for Solving the Problems] The method of the present invention developed to achieve the above object uses a mixture containing a plurality of elements mixed in a composition ratio capable of forming an intermetallic compound in the material of at least one member. using your body,
This self-heating process is achieved by heat-treating one member and the other member in contact with each other at a temperature at which an intermetallic compound is formed, and applying the heat generated during the formation of the intermetallic compound to the contact surface of both members. This is a manufacturing method characterized by joining both members to each other using.

It may be even better if the above-mentioned mixture is compressed by an appropriate means.

FIG. 1 shows an outline of the composite material manufacturing process according to the method of the present invention.

More favorable results can be obtained when the above heat treatment is performed while applying pressure greater than the weight of the members to be joined, for example by pseudo isostatic pressing (hereinafter referred to as PHIP) using granular material such as alumina or silica sand as a pressure medium. There are cases. The atmosphere during pressurization may be air or an inert gas, but the bonding strength and base material strength may be improved by using a vacuum or a redox atmosphere gas.

Furthermore, these atmospheres may be combined.

The raw material for one of the above members must be at least partially composed of a metal material before the formation of an intermetallic compound,
It may partially contain an intermetallic compound. In addition, suitable elements and compounds such as oxides, nitrides, and carbides are included in order to improve the properties of the composite material after joining, or to facilitate molding into the desired part shape. Good too.

The raw material does not need to be a pure metal lump, and may be a solid solution or a composite made by plating or the like. The form of the raw materials before mixing is powder.

They are flakes, wires, foils, etc.

When the raw materials are in the form of powder or flakes, the mixing method or pressing method is to extrude the mixed material using a V-type mixer, ball mill, mixer, etc., or to use mold press, hot press, or CIP (cold isostatic press molding). ) or crimped by HIP. Alternatively, the mixed raw materials may be packed into a metal pipe and then forged using a swaging machine until it reaches a predetermined outer diameter.

In the case of linear raw materials, the raw material wires are bundled or twisted together, and then the wires are crimped together using a wire drawing machine, swaging machine, extruder, or the like. In the case of foil-like raw materials, the foils are laminated in the thickness direction or rolled up after being laminated and then pressed together using a rolling device, swaging machine, or extruder.

The above molding step may be performed cold, but may also be performed warm in order to reduce deformation resistance during molding. In the case of warm forming, it is preferable that the temperature be below the temperature at which intermetallic compounds are formed, but if forming is completed in a short time that forms intermetallic compounds in a part of the structure, intermetallic compounds will not be formed. The molding may be performed at a warm temperature higher than the temperature.

The above-mentioned molding step may be carried out by an appropriate method in the air, in vacuum, inert gas, redox atmosphere gas, etc., or in a combination of these atmospheres.

[Function] One member processed into a desired shape before the formation of an intermetallic compound and the other member are heated to a temperature at which an intermetallic compound is formed. This heat treatment causes diffusion or self-combustion sintering to form an intermetallic compound, and at the same time, one member and the other member are joined by the heat generated during the formation of the intermetallic compound or by the heat of the self-combustion reaction. The temperature due to self-heating becomes higher than the heating temperature. In addition, in order to reduce deformation during heat treatment, it is preferable to set the heating temperature to a temperature range below the solidus line of the intermetallic compound. It may be necessary to maintain the above temperature for a certain period of time to terminate the formation of intermetallic compounds. The lower the temperature, the longer it takes.

The bonding mechanism according to the present invention is that the self-heating during the formation of the intermetallic compound softens or partially melts the bond interface, destroying the oxide film at the bond interface, or crushing the fine irregularities at the interface. This is thought to be due to intermolecular force or metallic bonding force due to complete contact between the two, and diffusion.

[Example] Examples of the present invention will be described below with reference to FIGS. 2 to 6. An example of the composite material A shown in FIGS. 3 and 4 includes one member 1 and the other cylindrical member 2.
It consists of A convex portion 3 is provided on one member 1,
The opening end of the other member 2 is fitted into this convex portion 3 .

An example of the manufacturing process shown in FIG. 2 includes a step 5 of mixing the raw materials of the mixed pressed body, which is the material of one member 1, and a mixing step of pressing the mixed raw materials to give a shape, which is performed as necessary. A crimped body manufacturing process 6, a pre-forming heat treatment process 7 performed as necessary, a molding process 8, a process 10 of manufacturing the other member 2, and a process of temporarily fixing one member 1 and the other member 2. 11, a step 12 of sealing the part to be joined, a heat treatment step 13 of heating to the temperature for forming an intermetallic compound, a processing step 14 after the heat treatment performed as necessary, and a heat treatment after the formation of the intermetallic compound. It includes a step 15 and a finishing step 16.

In step 5 of mixing the raw materials for one member 1, for example, A1 powder of 350 mesh or less produced by gas atomization method and sponge Ti powder of 850 mesh or less
The powders are mixed in a weight fraction of Ti:Al-64%:36% using a dry ball mill purged with Ar gas.

In step 6 of producing a pressed mixed body, a mold press is used to obtain a pressed mixed body (in this case, a green compact) having a desired shape.

Note that instead of performing mold pressing, the mixed raw materials may be packed in a vibrator and pressed into various shapes by rotary swaging or the like. Note that if the mixture is heat treated as it is in the heat treatment step 13, this step 6 may be omitted.

After the above step 6 is completed, if necessary, a pre-forming heat treatment step 7 such as annealing performed in a vacuum is performed to remove the processing strain when the mixed pressed body is manufactured in the above step 6, Reduce deformation resistance. Further, the pressure bonding surface of the mixed pressure bonded body is made stronger by diffusion, and the strength is improved.

The pre-forming heat treatment step 7 also has the effect of diffusing or removing impurity components in the mixture or mixed pressed body. This heat treatment step 7 may be performed in the air or vacuum, in an inert gas, a redox atmosphere gas, or a combination of these atmospheres.

The processing temperature is generally below the temperature at which intermetallic compounds are formed, but if the heating is short enough to form an intermetallic compound on a part of the bonded surface, it may be above the temperature at which an intermetallic compound is formed. It doesn't matter.

In the case of Ti-Al system, the temperature range is preferably from 200°C to 600°C.

Molding process 8
Forging or machining may also be performed. However, if the desired shape is obtained by the step 6, the heat treatment step 7 and the molding step 8 may be omitted.

In the manufacturing process 10 of the other member 2, A1 powder of 350 mesh or less produced by a gas atomization method and sponge Ti powder of 350 mesh or less were mixed in a weight fraction of Ti:Al-64%:36%, and Ar. Mix using a gas-substituted dry ball mill. after that,
The mixture is packed into a mold press or a vibrator and subjected to swaging processing to obtain a mixed and pressed body having a desired shape. Incidentally, this mixed press-bonded body may be molded by the same process as one of the members 1.

The material of one member 1 (mixed crimped body) and the material of the other member 2 (mixed crimped body) before intermetallic compound formation obtained through each of the above steps are temporarily fixed by fitting their joint parts together. be done. Methods for fixing both members 1.2 include pressure welding, friction welding,
Adhesives, brazing, bolting, etc. may also be employed.

The contact area of the joint between one member 1 and the other member 2 is preferably 0.001 mm2 or more, more preferably 0.01 mm2, in order to maintain the shape of the composite material A and obtain good joint strength.
Ai2 or higher is desirable.

Both members 1.2 fixed to each other in this way are sealed by sealing the joint part with a sealing material as necessary, so that the following P
When performing HIP, make sure that the granular material 2 does not get into the joint. The sealing material may include plates, wires, foils, powders, etc. made of the same composition as the above-mentioned mixed pressure-bonded body or other compositions, or other metals or ceramics, or inorganic adhesives, organic adhesives, and brazing materials. used. This sealing material may be filled into a groove or the like formed in advance at the edge of the joint. Further, in order to bring about the same effect as this sealing material, the entirety of both members 1.2 may be vacuum-sealed with metal 8 glass or the like.

The members 1 and 2 are placed in a PHIP apparatus 20 shown in FIG. 5, for example, and heated to a temperature at which an intermetallic compound is formed, and if necessary pressurized with pseudo-isostatic pressure. This device 20 includes: a pressure-resistant stainless steel pot 22 filled with a solid powder 21 such as alumina powder as a pressure medium; a Kanthal heater 23 which is a coiled resistance heating element built into the pot 22; A thermocouple 24 for temperature detection, a lid 25 made of stainless steel, a pressurizing means 26 such as a hydraulic cylinder that pressurizes the lid 25, a vacuum chamber 27 in the form of a closed container surrounding the pot 22, and this chamber. It is configured to include an exhaust device 28 and the like for exhausting the inside of 27.

The chamber 27 is kept airtight by a sealing material 29 such as an O-ring. The powder 21 may be any material as long as it has heat resistance and pressure resistance, so ceramic powder, carbon powder, or the like other than alumina powder may be used.

A pseudo isostatic pressure of, for example, 500 kgf'/cm2 is applied by the pressurizing means 26. Moreover, by evacuating the inside of the chamber 27 with the exhaust device 28, the inside of the pot 22 is also evacuated, and the pot 22 is heated to, for example, 900° C. by the heater 23. The temperature at this time can be measured by the thermocouple 24. When the mixed press-bonded body, which is the material of one member 1 and the other member 2, is heated to the above temperature, it forms an intermetallic compound by self-combustion sintering and generates heat at the same time, causing diffusion bonding at the bonding interface between them. Unify by doing things like Note that the pressure may be applied isostatically by HIP or the like using gas, liquid, or fluid as a pressure medium. Alternatively, the heat treatment step 13 may be performed at the same time as the mixture or pressed mixed body before intermetallic compound formation is formed into a predetermined shape by mechanically pressurizing by hot pressing using a mold.

In the case of Ti-Al type, it is preferable to pressurize it to 50 kg f /■2 or more. If the pressure is lower than this, the strength of the composite material will be drastically reduced. In order to obtain even higher strength composite materials,
200 ) cg f / cm 2 or more.

In the case of Tj-Al system, the heat treatment temperature may be 400°C or higher. If the temperature is below 400°C, the processing time will be long. Also, T
In the case of i-Al system, it is particularly preferable to use a vacuum atmosphere in order to obtain a high-strength composite material.

If done in the atmosphere, oxidation may progress and the strength may decrease.

The standard heat of formation of TiAl is ΔH298-75KJ/+0
01, and when the amount of heat generated during the formation of the intermetallic compound does not escape to the outside, the temperature of the composite is equal to or higher than the melting point of TiAl, and sufficient heat generation is obtained. Note that ΔH2,8 is -4
The effect is great when it is 0 KJ/mol or less.

Further, in the case of Tj-Al system, it is preferable that the temperature increase speed up to the above heat treatment temperature is 10° C./win or more. At this temperature increase speed, a rapid reaction occurs, so that the temperature of the composite is sufficiently increased.

When the above embodiment device 20 is used, a desired degree of vacuum can be applied to the surfaces and insides of the members 1 and 2.
If necessary, composite material A can be heated in a vacuum atmosphere to an intermetallic compound forming temperature. For this reason, composite material A
In addition to removing impurities contained in the pores, the number of pores can be further reduced. Further, although it may be performed in the atmosphere, it is also possible to form an intermetallic compound in a gas atmosphere by replacing the inside of the chamber 27 with a specific gas as necessary. In particular, by using PHIP, it can be easily applied to complex-shaped composite materials other than those of the above embodiments.

Note that, if necessary, after the heat treatment step 13 is completed, an appropriate processing step 14 such as forging may be carried out to improve defects and segregation between the base material and the joint, to disperse impurities, etc.

After the intermetallic compound is formed and bonded in the heat treatment step 13, if necessary, the composite material A is held at, for example, 900° C. while maintaining the pseudo-isotropic pressure and atmosphere, and heat-treated for 1 hour. Step 15 may also be performed. The treatment temperature is preferably in a temperature range below the solidus line of the intermetallic compound. In particular, in the case of Ti-Al system, the temperature is preferably 700°C or higher. At temperatures below this temperature, sufficient diffusion does not proceed. This heat treatment step 15 may be performed in the atmosphere, but more favorable results may be obtained if it is performed in an inert gas, vacuum atmosphere, redox atmosphere, or other gas. Furthermore, these atmospheres may be combined. Depending on the material, the heat treatment step 15 may be performed without applying pressure.

By performing the heat treatment step 15 after the formation of the intermetallic compound, it is possible to further reduce the pores included in the composite material A+, promote uniformity of the structure, remove bonding strain, and furthermore remove impurities. Diffusion or removal of impurities can be achieved. By carrying out this heat treatment step 15, it is also possible to adjust the size of crystal grains, intermetallic compound structure, or precipitates.

Through the above series of steps, (TiAl + Tis
A composite material A was obtained in which one member 1 made of an intermetallic compound of Al) and the other member 2 made of an intermetallic compound of (TiAI+Ti3At) were completely integrated. This composite material A had no defects that would pose a practical problem in the base material and the joint, was homogeneous, and had good joint strength.

FIG. 6 is a microscopic photograph of the joint of the composite material A. The structure of the joint was almost the same as that of the base metal, and the joint was so good that it was difficult to distinguish the joint.

Both the base material and the joint exhibit excellent heat resistance and oxidation resistance, and the joint strength is extremely high.

Note that the finishing step 16 may be performed after the heat treatment step 15 is completed. For example, the surface of the composite material A is made smooth by barrel processing or the like. Alternatively, the surface may be polished by machining, or the shape may be corrected or added to by removing or cutting surface scratches, the surface layer, etc., or by grinding, or where the sealant protrudes or the entire sealant. remove. Moreover, if compressive residual stress is generated in the surface layer of the composite material A by performing shot peening or the like, the durability of the composite material A can be further increased by 1q.

Note that one member 1 is made of a crimped mixture of Tj: Al-84% and 36%, and the other member 2 is made of Ti.
: When the same manufacturing process as in the above example was carried out using a mixed crimped body of Al-37, 17%: 82.83%, one member 1 made of an intermetallic compound (TjAI+Tji At) and an intermetallic A composite material was obtained in which the other member 2 made of the compound (Al3Ti) was perfectly joined.

The micrograph shown in FIG. 7 shows a joint of a composite material obtained by using a mixed crimped body of Tl2^1-64%236% for one member 1 and using Inconel MA754 for the other member 2. It shows. A sufficient diffusion layer or compound layer was formed at the joint, and a high-strength joint was obtained. The manufacturing process is similar to that of the previous embodiment (FIG. 2).

The other member 2 is made of Ni, Ni alloy, N1 base heat-resistant alloy, TI, Tf gold alloy A1. It may be metals such as A1 alloy, semi-metals such as 81, or inorganic materials such as intermetallic compounds, ceramics such as alumina, silicon nitride, silicon carbide, etc., and organic materials such as heat-resistant plastics may also be applicable. be. It is better if one member 1 and the other member 2 contain one or more common elements.

8 to 17 show examples of shapes of composite materials. The composite material A2 shown in FIGS. 8 and 9 is one in which one cam-shaped member 1 and the other shaft-shaped member 2 are joined together by the method described above. in this case,
By providing a groove 40 in the joint and filling the groove 40 with a sealing material 41, the granular material 21 is prevented from entering the joint during the PHIP.

The composite material A3 shown in FIGS. 10 and 11 has one member 1 having a tapered end 50 and the other member 2.
The bonding is performed while it is inserted into the taper hole 51 of. Composite material A4 shown in Figures 12 and 13
, one disc-shaped member 1 is joined to the end surface of the other piston-head-shaped member 2. Figures 14 and 15
The composite material A shown in the figure is one in which one member 1 having a bulb shape is joined to the other member 2 having a cylindrical rod shape. Alternatively, one member 1 and the other member 2 may be stacked and bonded in the thickness direction, as in composite material A6 shown in FIG. 16, or as in composite material A7 shown in FIG. 17. Alternatively, one member 1 and the other member 2 may be joined in the longitudinal direction.

Further, the present invention is not limited to what was shown in the above embodiments, but the present invention is also applicable to Ti
-It is also applicable to other compositions based on Al.

In particular, when the composition ratio of the mixed raw materials in at least one member is in the range of 14 to 63% Al and 86 to 37% Ti by weight, in a composite material made of a Ti-Al intermetallic compound, Due to the large heat generated during the formation of intermetallic compounds, a high-strength composite material with a porosity of 3% or less and a maximum defect of 100 μm or less was obtained.

The present invention can also be applied to systems that form other intermetallic compounds.

[Effects of the Invention] According to the present invention, large self-heating generated during the formation of an intermetallic compound can be applied to the bonding portion, which has the effect of preventing the occurrence of defects at the bonding interface and promoting the diffusion necessary for bonding. Even if the heating temperature is relatively low, a good joint can be easily obtained in a short time due to self-heating.

In addition, since the intermetallic compound is formed and bonded at a temperature considerably lower than the melting point of the intermetallic compound, even though the bonding temperature is low, after bonding, both the base material and the bonded part have a temperature equal to or higher than that of the intermetallic compound. It can demonstrate heat resistance and functionality.

[Brief explanation of the drawing]

Fig. 1 is a process explanatory diagram showing the method of the present invention, Fig. 2 is a process explanatory diagram showing an embodiment of the present invention, Fig. 3 is a perspective view showing an example of a composite material, and Fig. 4 is a process explanatory diagram showing an example of the composite material. A cross-sectional view of the composite material shown, FIG. 5 is a cross-sectional view of the apparatus for performing PHIP, FIG. 6 is a micrograph showing the metal structure of the joint at 600 times magnification, and FIG. 7 is a cross-sectional view of the metal structure of the joint. Fig. 8 is a perspective view showing an example of a composite material, Fig. 9 is a cross-sectional view of the composite material shown in Fig. 8, and Fig. 10 is a composite material. Fig. 11 is a cross-sectional view of the composite material shown in Fig. 10, Fig. 12 is a perspective view showing an example of the composite material, and Fig. 13 is a cross-sectional view of the composite material shown in Fig. 12. 14 is a perspective view showing an example of a composite material, FIG. 15 is a sectional view of the composite material shown in FIG. 14, and FIGS. 16 and 17 are examples of different composite materials. FIG. 1... One member, 2... Other member, 20...
Equipment for implementing PHIP. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 313 Part 4 Figure j I 5 Figure 1', Section ■ ×600 Figure 6/F unit P-( Figure 7 Figure 8 Figure 9 Figure j11o Figure Figure 11 Figure 12 Figure 13/ Figure 16 Figure 17

Claims (3)

[Claims] (1) A method for manufacturing a composite material formed by joining one member and another member, wherein the material of at least one member contains a plurality of elements mixed in a composition ratio capable of forming an intermetallic compound. Using the mixture, heat treatment is performed at a temperature at which an intermetallic compound is formed while the one member and the other member are in contact with each other, and the heat generated during the formation of the intermetallic compound is applied to the contact surface of both members. A method for manufacturing a composite material at least partially made of an intermetallic compound, characterized in that both members are joined to each other by utilizing this heat generation. (2) The method for manufacturing a composite material according to claim 1, characterized in that the joining is performed in a state where one member and the other member are pressurized during the heat treatment. (3) Manufacturing the composite material according to claim 1, wherein during the heat treatment, the one member and the other member are bonded under pressure in a predetermined atmosphere using a pseudo isostatic press. Method.