JP2009074106A - Method for forming and manufacturing object composed of intermetallic-compound alloy containing low-melting-point metal and high-melting-point metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming and manufacturing an intermetallic compound containing a low-melting-point metal and a high-melting-point metal. <P>SOLUTION: The method for forming and manufacturing an object composed of an intermetallic-compound alloy containing a low-melting-point metal and a high-melting-point metal comprises the following steps: a step in which the low-melting-point metal is oxidized in an oxidizing atmosphere into an oxide and the oxide is pulverized into powder and also the high-melting-point metal is pulverized into powder; a step in which the powder of the oxide containing the low-melting-point metal is compacted, together with the powder of the high-melting-point metal, into a green compact, and a mixing ratio between inert gas and reducing gas both forming an atmosphere for reducing the oxide is adjusted to regulate oxygen concentration in the atmosphere for reducing the oxide in the green compact and also regulate the reduction rate of the oxide containing the low-melting-point metal; and a solid-phase sintering powder metallurgy step in which the respective powders of the low-melting-point metal reduced in the above step and the high-melting point metal are subjected to solid-phase sintering with each other at diffusion and reaction temperatures. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming and manufacturing an object of an intermetallic alloy containing a low melting point metal and a high melting point metal. More specifically, the method for forming and manufacturing an intermetallic alloy object according to the present invention uses a green compact in which a low melting point metal oxide powder and a high melting point metal powder are uniformly mixed. By reducing the low melting point metal oxide at the high temperature at which the metal originally melts, both low melting point metal and high melting point metal powders can be solid-phase sintered together at the diffusion temperature and reaction temperature. The present invention relates to solid phase sintered powder metallurgy.

  Functional intermetallic compound alloys such as thermoelectric materials used in high-temperature electric furnaces are often brittle materials, so it is difficult to form them into predetermined shapes. There are many advantages to forming by powder metallurgy. However, when the intermetallic alloy contains a low-melting point metal element such as Sn, the low-temperature liquid phase of the low-melting point metal element will be involved in the sintering, and the non-equilibrium reaction and solidification process cannot be avoided. It is difficult to form and produce an object of the final shape intermetallic compound alloy by forming a heterogeneous multiphase coexisting structure.

  In addition, various intermetallic compound alloys used as heat-resistant structural materials and functional materials are attracting attention in the powder metallurgy method. The production method by the powder metallurgy method can be roughly classified into a dissolution and solidification method in which each powder raw material is dissolved and a powder metallurgy method in which raw material powder is sintered as it is. An intermetallic compound alloy of refractory metal elements having a wide stoichiometric composition and a wide temperature range can be produced without any problem by the melt solidification method. In this melting and solidification method, an intermetallic compound material is melted by arc melting and high-frequency melting, and then cooled and solidified as it is or cast into a mold. In addition, single crystal alloys of intermetallic compounds are widely produced by unidirectional solidification using the Bridgeman method, the Czochralski method (pulling method), the floating zone melting method, and the like.

  On the other hand, in order to compensate for the disadvantage of forming and manufacturing an intermetallic compound alloy body that is extremely fragile, a sintered powder metallurgy method that can perform forming and manufacturing in a series of steps is effective. In this sintered powder metallurgy method, raw material ingots produced by melting and solidification are pulverized to produce raw material powder, and then a green compact obtained by compression-molding this raw material powder is sintered at a temperature below the melting point. The powder metallurgy method that sinters at a temperature below this melting point includes, as an application example, a method of sintering while applying a load at a high temperature, such as hot pressing and plasma discharge sintering, and reaction heat using constituent metal element powders. There are a self-combustion type reaction sintering method for forming a compound, and a liquid phase sintering method using a partial molten state.

  Since intermetallic compounds have a narrow stoichiometric composition and complicated reaction paths, there are many problems in the production of intermetallic alloys. In particular, in the case of an intermetallic compound alloy containing both high-melting-point and low-melting-point metal elements, there is a problem that cannot be avoided by the typical melt-solidification method and powder metallurgy method, which are conventional production methods. When the melting point difference of each metal element constituting the intermetallic compound alloy is large, the liquid phase surface of each metal element becomes steep, so the target intermetallic compound is often formed by peritectic reaction. The composition of the liquid phase is large and moves toward the low melting point metal element, resulting in non-equilibrium and non-uniform solidification. Therefore, even if the initial charged composition is a single phase of an intermetallic alloy, it has a multiphase structure that actually includes a non-equilibrium phase. Furthermore, when this powder metallurgy method is used, there is a problem that sufficient atomic diffusion cannot be expected because the sintering temperature is limited by a metal element having a low melting point. If the sintering temperature is increased, the liquid phase is involved in the reaction. It cannot be avoided that sintering occurs. In the case of liquid phase sintering, the advantage that the reaction is rarely expected can be expected, but a non-equilibrium and non-uniform reaction becomes a problem as in the above-described solution solidification method.

  The present invention is directed to a method for forming and manufacturing an object of an intermetallic compound alloy containing a low melting point metal and a high melting point metal. As described in the above prior art, when producing an intermetallic compound alloy containing a relatively low melting point metal and a high melting point metal, the difference in melting point of each constituent metal element constituting the intermetallic compound alloy is a problem. Become. When a constituent metal element having a remarkably lower melting point than other constituent metal elements is present in the intermetallic alloy, it is necessary to keep the sintering temperature extremely low, or a partial molten state is required for high temperature sintering. It is necessary to allow. In the sintering of this intermetallic compound alloy, it is advantageous that the reaction rate of diffusion of each constituent metal element and formation of the intermetallic compound alloy is higher, but the liquid phase in the molten state does not necessarily react. It is not useful for promotion.

  The fact that an intermetallic alloy has a low melting point metal element as a constituent metal element means that the gradient of the liquid phase surface in the phase diagram is steep, and is the target intermetallic alloy formed by peritectic reaction? Or a peritectic reaction is indirectly involved. As a result, the composition of the liquid phase of the intermetallic alloy is greatly shifted to the low melting point metal element side, so that a non-uniform and non-equilibrium multiphase structure is formed through a non-equilibrium solidification process. In order to avoid these problems, it is necessary to develop a new powder metallurgy method capable of forming and producing an intermetallic compound alloy at a high temperature.

  The above-mentioned problems in forming and manufacturing an intermetallic compound alloy can be solved by the present invention. There are many promising alloy systems as thermoelectric materials for Sn-based half-Heusler type intermetallic compound alloys, which are desirable in the method of forming and manufacturing intermetallic compound alloys of the present invention. Since the half-Heusler intermetallic compound alloy can achieve high performance at high temperatures, it is expected to be used for electric energy recovery technology from waste heat. Furthermore, since various intermetallic compound alloys containing Sn or other low melting point metal elements exist in the intermetallic compound alloys other than the half-Heusler type, the metal comprising the low melting point metal and the high melting point metal according to the present invention. The method of forming and manufacturing an intermetallic alloy object has a wide range of applications.

  According to the method of forming and manufacturing an object made of an intermetallic compound alloy including a low melting point metal and a high melting point metal according to the present invention, the low melting point metal oxide powder is stirred and uniformly mixed with the high melting point metal powder. The mixed powder is compression-molded to form a green compact, and the oxide in the green compact is adjusted by adjusting the mixing ratio of an inert gas and a reducing gas to form an atmosphere in which the oxide is reduced. Adjusting the reducing gas concentration or oxygen partial pressure of the reducing gas atmosphere to be used for reducing the oxygen and adjusting the reduction rate of the oxide containing the low melting point metal, and the green compact reduced in the above step A solid-phase sintered powder metallurgy process in which both the low-melting-point metal oxide and the high-melting-point metal in the green compact are solid-phase sintered at a diffusion temperature and a reaction temperature. And Note that this step may include a step of producing both the low-melting-point metal oxide and the high-melting-point metal powder. The low melting point metal is oxidized in an oxidizing atmosphere to form an oxide, and the oxide is pulverized to form a powder. In addition, the refractory metal is formed into a powder using an applicable powder preparation process such as a gas atomization method, a reduction method, or mechanical cutting.

The method for forming and manufacturing an object of an intermetallic compound alloy according to the present invention is characterized in that the intermetallic compound alloy is any one of Ni ₃ Sn, Ni ₃ Sn ₂ and Ni ₃ Sn ₄ .

The method for forming and manufacturing an object of an intermetallic alloy of the present invention is characterized in that the low-melting-point metal oxide is any one of SnO ₂ and SnO.

The method for forming and manufacturing an intermetallic alloy object according to the present invention includes a diffusion temperature and a reaction temperature of both the low melting point metal and the high melting point metal, and a temperature not lower than the melting point of the oxide of the low melting point metal. It is a range. Further, the method for forming and manufacturing an object of the intermetallic compound alloy of the present invention is characterized in that the diffusion temperature and reaction temperature of both the low melting point metal and the high melting point metal are in a temperature range of 500 ° C. to 800 ° C. And
For example, the melting point of the oxide SnO ₂ formed of the low melting point metal is 1127 ° C., whereas the melting point of the low melting point metal Sn is 232 ° C. Therefore, by using the oxide SnO ₂ instead of the low melting point metal Sn as the raw powder of the sintered powder metallurgy method, the sintering can be performed at a high temperature where diffusion and reaction are active, and the reducing atmosphere is adjusted. Thus, a high-melting intermetallic compound alloy such as Ni ₃ Sn can be directly produced while controlling the rate of reducing SnO ₂ to Sn.

In the method for forming and manufacturing an object of an intermetallic alloy according to the present invention, the inert gas forming the atmosphere in which the oxide is reduced contains less than 4 vol% of at least one element of Group VIII of the periodic table, and The reducing gas forming the reducing atmosphere is at least one element gas of H ₂ , H ₂ S, CO, CO ₂ , SO ₂ , Na (H ₂ PO ₃ ), and Na ₂ S ₂ O ₃ , and 4 vol. % To 100%.

  The method of forming and manufacturing an object of an intermetallic compound alloy according to the present invention is a new method based on a powder metallurgy method in which forming and manufacturing can be performed simultaneously, and is an object of an intermetallic compound alloy that is fragile and difficult to form. Can be manufactured together with molding.

  The method of forming and manufacturing an object of the intermetallic alloy of the present invention is a composition of an intermetallic alloy having a single phase structure that could not be created by the conventional powder metallurgy method, as detailed in the examples. Even in this case, the Ni-Sn binary metal is obtained by the reduction reaction and the reactive sintering of the low melting point metal oxide and the high melting point metal using the method for forming and manufacturing the object of the intermetallic alloy of the present invention. An intermetallic body and its single phase alloy body could be fabricated.

When Sn metal element powder, which is a conventional method, is used as a raw material, the melting point of Sn metal element is melted at a temperature of 232 ° C., so that reactive sintering in the Sn liquid phase proceeds locally. Deviation in the composition of Sn forming the intermetallic alloy accelerates and manifests non-equilibrium solidification. Therefore, by replacing the Sn metal element powder with the oxide SnO ₂ powder, it is possible to avoid a local reaction due to the liquid phase and to control the process of reaction sintering and compound formation by a reduction reaction. As a result, it has become possible to produce an object of an intermetallic compound and an object of a single-phase alloy which are target generation phases of the present invention.

Since the volume shrinkage occurs due to the reduction reaction of the oxide SnO ₂ of the low melting point metal Sn, the formed intermetallic compound alloy is in a porous state. In the present invention, it has been clarified that a porous state having a high porosity is obtained by reactive sintering of a green compact of an oxide powder without load stress.

  However, in the present invention, if the green compact of the oxide powder is subjected to reduction reaction and reaction sintering under pressure using a hot press or the like, the density is avoided by avoiding a predetermined porous state of the green compact. Can be adjusted freely. In recent intermetallic compound alloys, the trend of research that considers a predetermined porous state as a material structure and actively uses it to improve functionality has recently been increasing. Controlling the porous state, that is, the size of the voids (pores) by the powder particle diameter leads to control of the functionality of the intermetallic alloy. For example, in the present invention, in the case of a thermoelectric material whose application of this process is also a goal, the effect of reducing the thermal conductivity while maintaining the electrical characteristics by uniformly dispersing the porous state, that is, the pores (pores) Can be obtained.

  Furthermore, the process according to the invention has advantages over conventional powder metallurgy methods. In the case of ordinary powder metallurgy using metal element powder that is not oxide powder, it is necessary to pay close attention to prevent oxidation of metal element powder in each process from the stage of sample preparation to sintering heat treatment. . However, in the method devised in the present invention, an oxide is used as a raw material powder, and an intermetallic compound is formed and reacted by a heat treatment in a reducing atmosphere. There is an advantage that can be avoided.

The present invention is to mold and manufacture an object made of an intermetallic compound alloy containing a low melting point metal and a high melting point metal. Since the low melting point metal used in the present invention is an oxide obtained by oxidizing this low melting point metal, it is common that the melting point of the oxide is high. For example, in the present invention, the melting point of metal Sn is 232 ° C., but the melting point of SnO ₂ , which is an oxide of Sn as a raw material, is 1127 ° C., which is 895 ° C. higher than the melting point of metal Sn. The reduction of the Sn oxide to the metal element depends on the thermal stability of the Sn oxide, but the Sn oxide can be reduced to the metal element by a relatively simple reduction reaction. Therefore, the method of forming and manufacturing an intermetallic compound alloy containing a low melting point metal and a high melting point metal according to the present invention is a solid phase sintering in which oxide SnO ₂ is sintered as a raw material powder instead of Sn, which is a low melting point metal element. A new powder metallurgy method for producing low-melting point metals and intermetallic compound alloys containing high-melting point metals can be established by performing a reduction reaction and a sintering reaction at high temperatures using the powder metallurgy method. I thought.

  In the present invention, when an intermetallic compound alloy containing a low-melting-point metal and a high-melting-point metal is produced by a conventional powder metallurgy method, the problem is that the sintering temperature is suppressed below the low melting point of the low-melting-point constituent metal element. Is Rukoto. On the other hand, when sintering an intermetallic compound alloy containing a low-melting-point metal and a high-melting-point metal at a high temperature, the problem is that the low-melting-point metal becomes a liquid-phase sintering resulting in a non-equilibrium solidification structure. That is. In solving these problems, the present invention provides a new powder metallurgy method that can produce an intermetallic compound alloy containing a low melting point metal and a high melting point metal at high temperatures so as to avoid the formation of a non-uniform nonequilibrium solidification structure. provide.

Example 1
First, in order to avoid partial melting when holding at a temperature higher than the melting point of the low melting point metal element, do not use the metal element powder of the low melting point metal element, but use the oxide powder of the low melting point metal element as the raw material powder. There is a feature. In the embodiment of the present invention, the oxide SnO ₂ is used as the low melting point metal element Sn. In the powder metallurgy method, the particle size of the powder is an important factor that determines the formation reaction of the compound because the diffusion and reaction are controlled at the interface between the powders. Therefore, it can be said that one of the advantages of using the oxide powder as a raw material is that the oxide powder is easier to control the size of the powder particle size than the low melting point metal element powder.

Next, as a raw material powder, an oxide powder of a low melting point metal element and an elementary powder of another constituent metal element are mixed, and a heat treatment for sintering is performed at a high temperature. Unlike conventional powder metallurgy, the sintering process consists of a reduction reaction of oxide powder, atomic diffusion at the interface and a compound formation reaction. The reducing atmosphere is at least one element gas of H ₂ , H ₂ S, CO, CO ₂ , SO ₂ , Na (H ₂ PO ₃ ), and Na ₂ S ₂ O ₃ . In one embodiment, it is easy to use H ₂ gas as the reducing atmosphere, and it is possible to consider safety like Ar-4% H ₂ gas. Factors that control the reduction reaction include the H ₂ gas concentration and flow rate as the reducing atmosphere, the introduction temperature of the reducing gas in the temperature history, and the holding time. Sn reduced from SnO ₂ exists as a liquid phase at a high heat treatment temperature, but the formation reaction is controlled by adjusting the amount of the Sn liquid phase according to the reduction conditions. If reducing conditions such as oxygen partial pressure are adjusted, the reduced Sn may directly form an intermetallic compound alloy without going through the liquid phase. If the liquid phase can be avoided completely, it can greatly contribute to the uniform adjustment of the structure of the intermetallic compound alloy.

In order to uniformly produce the intermetallic compound phase by the method of this example, the reduction reaction of the oxide powder, the subsequent atomic diffusion at the interface, and the formation reaction of the compound phase are important. Here, the particle size and mixing state of each raw material powder are the keys that have a great influence on the reaction process. In order to promote the reduction reaction, it is effective to remarkably increase the active surface area by reducing the particle diameter of the oxide SnO ₂ powder. Since the generally available powder particle size determines the economic factor of cost, the standard oxide powder particle size was set to 1 μm. Similarly, the metal element powder for the raw material to be mixed is considered to be about 1 μm to 45 μm. Needless to say, controlling the mixing state of the powder is important to ensure the uniformity of the reaction. In this embodiment, a planetary ball mill is used. However, in order to avoid pulverization, adhesion, and mechanical alloying, the operation is performed under a low energy stirring condition. Specifically, instead of a ball, beads having a diameter of about 3 mm (typically 10 mm or less) are used, the rotation speed is kept low (about 300 rpm), and the rotation is 60 seconds without stopping and the interval of 10 seconds is stopped. The rotation direction was reversed every time. Moreover, ethanol was used as the organic solvent. The mill container capacity, beads, and volume ratio of the mixed powder sample were adjusted to be approximately equal.

Example 2
As a new powder metallurgy method for producing a high melting point intermetallic compound alloy containing a low melting point metal element as a constituent metal element, a reactive sintering method utilizing an oxide reduction reaction at a relatively high temperature has been established.

Considering the expansibility and practical aspects of the present invention, it is desirable that the present invention can be applied to the production of multicomponent intermetallic compound alloys that are expected as promising practical candidate materials such as thermoelectric materials. However, in a multi-component system, the possibility that an intermetallic compound alloy in an alloy system corresponding to the number of combinations of constituent metal elements is locally formed increases. In addition, the phase equilibration becomes increasingly complex as the number of constituent metal elements increases the degree of freedom in the phase rule. Therefore, in the present invention, three types of intermetallic compound alloys Ni ₃ Sn, Ni ₃ Sn ₂ , and Ni ₃ Sn ₄ existing in the Ni—Sn binary system are prepared in order to establish a basis for a new alloy manufacturing process to be developed. did. FIG. 1 shows a phase diagram of the Ni—Sn binary system. Ni ₃ Sn and Ni ₃ Sn ₂ present in the composition on the Ni-rich side are compounds having a relatively high melting point, and Ni ₃ Sn ₄ of the Sn-rich composition has a slightly low melting point and can be formed by a peritectic reaction. It is characteristic.

As raw material powders to be used, the following high purity pure metal powder and oxide powder (purity, powder particle size) were prepared.
Ni (> 99.9%, 1 μm), Sn (> 99.9%, 38 μm), SnO ₂ (> 99.9%, 1 μm)
In all cases, the smallest particle size was selected from among generally available powders, and only powders having a larger particle size than SnO ₂ (and Ni) were available (June 2006). As described above, an oxide can be advantageous in that it is easy to produce a fine particle size powder. These powders were weighed with an electronic balance so as to be Ni ₃ Sn, Ni ₃ Sn ₂ , and Ni ₃ Sn ₄ as target production phases, and stirred and mixed using a planetary ball mill. The container and beads used were ZrO ₂ which has excellent wear resistance. Since mixing is the purpose here, in order to avoid crushing and mechanical alloying, small-diameter beads are used instead of balls, the number of rotations is suppressed to 330 rpm, and a cycle of 60 seconds for rotation and 10 seconds for stop totals 30 cycles. I went twice. For uniform mixing, the direction of rotation was reversed every cycle and ethanol was used as the solvent.

  The uniformly mixed powder was loaded into a die and a punch and molded as a green compact using a hydraulic press. The green compact has a diameter of 10 mm and a thickness of about 5 mm. The formed green compact was subjected to reactive sintering based on each heat treatment condition.

For Ni ₃ Sn having the most Ni-rich composition, the present process using the SnO ₂ oxide reduction reaction was compared with the conventional method using Sn powder. Since the composition has a low melting point and low Sn, it can be said that it is the easiest composition for the conventional method. The heat treatment profile was common to both, and the temperature was increased from room temperature to 800 ° C. at 10 ° C./min, held for 1 h, and then cooled by furnace cooling. In this step, Ar-4% H ₂ gas is flowed at a flow rate of 400 cc / min as a reducing atmosphere from the time of temperature increase, and Ar-4% Ar − is heated to 800 ° C. in an Ar gas atmosphere. Experiments were conducted on two cases of switching to 4H ₂ gas and flowing at a flow rate of 400 CC / min. On the other hand, in the conventional method, an Ar gas atmosphere in which a flow rate is 400 CC / min is used. The results of producing a Ni ₃ Sn sample by this step and the conventional method will be compared using FIGS. 2A and 2B and FIGS. 3A and 3B. FIG. 2 (a) shows a structure observed by a backscattered electron image (BEI) of a Ni ₃ Sn sample prepared by this process, and FIG. 2 (b) shows a typical profile of X-ray diffraction (XRD). Indicates. First, what is important is that a sample having a single phase structure of Ni ₃ Sn can be produced by this step. A sample having a single phase structure of Ni ₃ Sn can be confirmed in both a backscattered electron image (BEI) and an X-ray diffraction (XRD) profile. On the other hand, the structure and typical XRD profile by BEI of the Ni ₃ Sn sample produced by the conventional method are shown in FIGS. As described above as a problem of the conventional method, a non-uniform and non-equilibrium solidified structure is formed in FIG. Sn is in a molten state during the temperature rise, and the Ni ₃ Sn formation reaction proceeds but is local. Ni ₃ Sn ₂ phase is formed by non-equilibrium solidification during cooling, and Ni remains as a solid solution phase. It can be clearly seen from the contrast of the BEI that these coexisting phases exist at a considerable volume ratio. For the purpose of shortening the time during which an unnecessary reaction due to the Sn liquid phase proceeds, an attempt was made to prepare by a conventional method by increasing the temperature rising rate to 200 ° C./min. Although the volume fraction of the coexisting phase other than the Ni ₃ Sn phase decreases, a Ni ₃ Sn single phase structure cannot be obtained.

From the above comparison, it can be clearly shown that this process is effective for the production of a Ni ₃ Sn single-phase sample. When samples having the same composition are prepared by the Arc dissolution method, a multiphase structure in which the Ni ₃ Sn ₂ phase and the Sn phase coexist is obtained. Although the volume fraction of the coexisting phase is relatively small, there are a large amount of microcracks due to solidification defects and thermal stress during cooling.

Here, as can be seen from the BEI shown in FIG. 2B, the Ni ₃ Sn single-phase sample prepared in this step is porous and its porosity is relatively large. Generally, in powder metallurgy, volume shrinkage occurs due to the absence of voids between powders as sintering proceeds. In this step, because the volume is contracted at more reduction of _{SnO 2 SnO 2 + 2H 2 →} Sn + 2H 2 O. In this example, the green compact is subjected to heat treatment for reaction sintering as it is, but it is possible to control the density of the sample by performing reaction sintering while applying a load in combination with a hot press or the like. is there. Recently, porous materials that actively introduce pores of various sizes have been developed. For example, when aiming at application to the production of thermoelectric materials, the material is porous. It is thought that it is useful for improving thermoelectric characteristics.

Samples of Ni ₃ Sn ₂ and Ni ₃ Sn ₄ were prepared by this step. As a result of producing Ni ₃ Sn ₂ in FIGS. 4A and 4B, a BEI structure and a typical XRD profile are shown. The conditions are the same as in the case of Ni ₃ Sn. In the case of the Ni ₃ Sn ₂ sample, some peaks that cannot be identified in the XRD profile can be confirmed, but a substantially single-phase structure can be formed. Furthermore, in the case of Ni ₃ Sn _{4 having} a Sn-Rich composition, a sample having a structure close to a single phase can be produced in the same manner as Ni ₃ Sn ₂ . An appearance photograph and a typical XRD profile of the Ni ₃ Sn ₄ sample are shown in FIGS. 5 (a) and 5 (b). For this sample, since SnO ₂ volume ratio of the raw material is the largest since the most Sn-rich composition in three samples, are completely during heat treatment there is SnO ₂ remaining without being reduced Yes. In addition, the largest volume shrinkage is clearly recognized from the appearance of the sample. That is, in the production of the intermetallic alloy Ni ₃ Sn ₄ having a large composition of the low melting point metal element Sn, it is important to adjust the conditions related to the reduction reaction of the oxide SnO ₂ powder. It was confirmed that the SnO ₂ powder remaining at the holding time of 1 h was completely reduced by extending the holding time to 3 h.

FIG. 1 is a diagram showing three intermetallic compounds, Ni ₃ Sn, Ni ₃ Sn ₂ , and Ni ₃ N ₄ , produced using the process of the present invention, on a Ni-Sn binary phase diagram. FIG. 2A shows a structure observed by back-reflection electron image (BEI) of a Ni ₃ Sn sample prepared by this process, and FIG. 2B shows a typical profile of X-ray diffraction (XRD). Indicates. FIG. 3A shows a structure observed by a back-scattered electron image (BEI) of a Ni ₃ Sn sample prepared using a low melting point metal Sn by a conventional method, and FIG. 3B shows an X-ray diffraction pattern. (XRD) shows a typical profile. FIG. 4 (a) shows a structure observed by a backscattered electron image (BEI) of a Ni ₃ Sn ₂ sample prepared by this process, and FIG. 4 (b) shows a typical X-ray diffraction (XRD). Indicates a profile. FIG. 5 (a) shows a photograph of the appearance of a Ni ₃ Sn ₄ sample prepared by this process and a typical profile of X-ray diffraction (XRD).

Claims (6)

A method of forming and manufacturing an object made of an intermetallic alloy containing a low melting point metal and a high melting point metal,
The low-melting-point metal oxide powder is stirred and mixed uniformly with the high-melting-point metal powder, and the mixed powder is compression-molded to form a green compact to form an atmosphere for reducing the oxide. By adjusting the mixing ratio of the inert gas and the reducing gas, the reducing gas concentration or oxygen partial pressure of the reducing gas atmosphere that is flowed to reduce the oxide in the green compact is adjusted, and the low melting point A step of adjusting a reduction rate of the oxide containing metal, and a diffusion temperature of both the low-melting-point metal oxide and the high-melting-point metal powder in the green compact reduced in the step And a solid phase sintered powder metallurgy process that solid phase sinters each other at reaction temperature,
A method for forming and manufacturing an object of an intermetallic compound alloy comprising the low melting point metal and the high melting point metal. Wherein said intermetallic compound _alloy, Ni 3 Sn, molding fabricated objects intermetallic alloy according to claim 1, characterized in that any one of _Ni 3 Sn ₂ and _Ni 3 Sn _4. 3. The method of forming and manufacturing an object of an intermetallic compound alloy according to claim 1, wherein the oxide of the low melting point metal is any one of SnO ₂ and SnO.   The diffusion temperature and reaction temperature of both the low-melting-point metal and the high-melting-point metal are in the temperature range of 300 ° C to the melting point of the low-melting-point metal oxide. A method for forming and manufacturing an object of an intermetallic compound alloy according to 1.   The intermetallic compound alloy according to any one of claims 1 to 4, wherein a diffusion temperature and a reaction temperature of both the low melting point metal and the high melting point metal are in a temperature range of 500 ° C to 800 ° C. A method of molding and manufacturing an object. The inert gas that forms the atmosphere for reducing the oxide contains less than 4 vol% of at least one element of Group VIII of the periodic table, and the reducing gas that forms the reducing atmosphere includes H ₂ , H ₂ S , CO, CO ₂ , SO ₂ , Na (H ₂ PO ₃ ), and Na ₂ S ₂ O ₃ , including at least 4 vol% to 100%
A method for forming and producing an object of an intermetallic compound alloy according to any one of claims 1 to 5.