TW201325814A - Methods of manufacturing multi-element thermoelectric alloys - Google Patents

Abstract

Disclosed is a method of forming a multi-element thermoelectric alloy. A plurality of binary alloys and milling balls are put in a milling pot to process a ball-milling process to obtain a multi-element thermoelectric alloy powder. The milling balls have a diameter of 1 mm to 10 mm. The milling balls and the binary alloys have a weight ratio of 1: 1 to 50: 1. The milling rotation rate is of 200 rpm to 1000 rpm. The ball-milling process is processed for 4 hours to 12 hours.

Description

Method for forming multi-component thermoelectric alloy

The present invention relates to thermoelectric materials, and more particularly to methods of forming the same.

Thermoelectric materials perform direct conversion of thermal energy and electrical energy by controlling the movement of internal carriers, without the need for mechanical components. Thermoelectric materials can be used in thermoelectric power generation, waste heat recovery, electronic component cooling, and air conditioning systems. Evaluating the conversion efficiency between thermal energy and electrical energy of thermoelectric materials is usually expressed in terms of thermoelectric figure of merit (ZT value). ZT = S ² σT / κ, where S is the Seebeck coefficient, σ is the conductivity, T is the absolute temperature, and κ is the thermal conductivity. The higher the ZT value, the higher the conversion efficiency of thermal energy and electrical energy of the thermoelectric material. A thermoelectric material having a high ZT value can be obtained by increasing the conductivity σ of the material and the Seebeck coefficient S, or by reducing the thermal conductivity κ.

The method of making multi-component thermoelectric alloys is to use alloy rods and elemental powders. In the production of alloy rods, the high-temperature process of alloy melting usually leads to the loss of some constituent elements, resulting in the ratio of alloy composition to the preset ratio. The difference. At the same time, in the research results of the thermoelectric alloy, it is also found that the powder obtained by the alloy rod has the interaction between the defects during the ball milling process, resulting in a decrease in the thermoelectric properties. For example, the p-type BiSbTe alloy powder may be misaligned during ball milling (Anti -site defects) interact with voids (Vacancies) to produce excessive electrons that affect the thermoelectric properties of the bulk. In order to avoid such problems, the use of elemental powders directly for long-term mechanical alloy ball milling is also used to make multi-component thermoelectric alloys. However, the alloying ball milling time is quite long (up to several tens of hours), and the alloy powder is liable to have problems of insufficient alloying and uneven composition, thereby reducing the application value of alloying using elemental powder.

In summary, there is a need for a new method for preparing a plurality of thermoelectric alloy powders and thermoelectric materials.

An embodiment of the present invention provides a method for forming a multi-component thermoelectric alloy, comprising: placing a plurality of binary alloys and ball-milling beads in a ball-milling tank, performing a ball milling process under argon to form a multi-component thermoelectric alloy powder, wherein the ball-milling beads Between 1mm and 10mm in diameter, the weight ratio of ball bead to binary alloy is between 1:1 and 50:1, the ball mill speed is between 200 rpm and 1000 rpm, and the ball milling process lasts 4 to 12 hours. .

An embodiment of the present invention directly uses different compound powders such as a binary alloy for alloy preparation. For example, when the binary alloy is a combination of Bi ₂ Te ₃ and Sb ₂ Te ₃ , a high-energy ball mill will form a ternary alloy powder Bi _x Sb _2-x Te ₃ , where x is between 0.1 and 0.8. between. In an embodiment of the invention, x is between 0.3 and 0.6. When the binary alloy is a combination of Bi ₂ Te ₃ and Bi ₂ Se ₃ , a high-energy ball milling will form a ternary alloy powder Bi ₂ Se _y Te _3-y , where y is between 0.1 and 0.8. When the binary alloy is a combination of PbTe and SnTe, a high-energy ball milling will form a ternary alloy powder Pb _z Sn _1-z Te, where z is between 0.1 and 0.9. In an embodiment of the invention, z is between 0.6 and 0.9.

In other embodiments of the present invention, when the binary alloy is a combination of PbTe and AgSb, a combination of PbAg and Sb ₂ Te ₃ , or a combination of PbSb and AgTe, a quaternary alloy Ag _m Pb _n Te _{p is} formed after high energy ball milling. Sb, wherein m is between 0.1 and 1, n is between 15 and 25, and p is between 15 and 25. In this embodiment, other metal compounds such as PbI ₂ , TeI ₄ , SbI ₂ , or AgI may be further added to adjust the proportion of elements in the alloy. In order to form the quaternary alloy powder Ag _m Pb _n Te _p Sb, other combinations of binary alloys and metal compounds such as PbAg, PbSb, and TeI ₄ , PbAg, PbTe, and SbI ₂ , PbTe, may be used. Combination of PbSb, AgI, or AgTe, AgSb, and PbI ₂ . To form a five-element alloy powder Ag _m Pb _n Te _p SbI _q , where m is between 0.1 and 1, n is between 15 and 25, p is between 15 and 25, and q is between 0.1 and Between 1 and other combinations of binary alloys and metal compounds, such as PbAg, PbSb, combination with TeI ₄ , PbAg, PbTe, combination with SbI ₂ , PbTe, PbSb, combination with AgI, or AgTe, AgSb And the combination of PbI ₂ .

The ball milling process is one of the key points of the invention. Appropriate ball milling energy is beneficial to form a stable multi-component thermoelectric alloy powder, and the ball milling method has rotation, stirring and vibration. In an embodiment of the invention, a plurality of binary alloys and ball beads are placed in a ball mill tank, and a ball milling process is performed under argon to form a multi-component thermoelectric alloy powder. The ball beads can be stainless steel and have a diameter between 1 mm and 10 mm. If the diameter of the ball bead is too small, the impact energy during ball milling is low, resulting in poor alloying. If the diameter of the ball beads is too large, the degree of grinding refinement is limited. The weight ratio of ball beads to binary alloy is between 1:1 and 50:1. If the proportion of the ball beads is too high, the ball grinding path is too short and the ball grinding energy is low. If the proportion of the ball beads is too low, the ball beads will hit each other less frequently and the overall ball grinding energy is low. The ball mill speed is between about 200 rpm and 1000 rpm or between about 300 rpm and 600 rpm. If the ball milling speed is too high, the ball grinding energy is too high and the component loss is increased. If the ball milling speed is too low, the ball milling energy is too low, resulting in a low degree of alloying. The ball milling process takes about 4 to 12 hours or about 5 to 10 hours. If the ball milling process is too short, the ball milling alloying is incomplete and it is easy to have an unalloyed binary alloy. If the ball milling process takes too long, the interaction between defects is long, resulting in excessive reverse carrier generation.

Then, the multi-component thermoelectric alloy powder formed above can be combined with spark plasma sintering technology to form a disordered nanostructure thermoelectric alloy having internal phonon scattering, low thermal conductivity, and high electrical conductivity. The whole thermoelectric alloy process can obtain high-alloyed thermoelectric alloy powder in a short time, has a fast sintering process and has the potential to be mass-produced. Therefore, a high-heat-good value multi-component thermoelectric alloy is prepared by using different compound powder methods, and has an adjustment. The elasticity of the material composition and the stability of the alloy composition can be a material process with commercial value.

The spark plasma sintering process is also one of the focuses of the present invention. In one embodiment of the invention, the multi-component thermoelectric alloy powder formed by the ball milling process is sintered and extruded under argon or vacuum in a spark plasma sintering process to form a thermoelectric bulk material. The temperature of the spark plasma sintering process is between 300 ° C and 600 ° C. If the temperature of the spark plasma sintering process is too high, the powder melts and the components are easily lost. If the temperature of the spark plasma sintering process is too low, the powder is sintered to a low density and there are many void defects. The holding time of the spark plasma sintering process is between 3 and 30 minutes. If the holding time of the spark plasma sintering process is too long, the grain size in the sintered bulk material grows due to long-time heat treatment, and the nano grain structure disappears. If the holding time of the spark plasma sintering process is too short, the powder sintering is not completely dense, and the bulk porosity is high. The spark plasma sintering process is heated from room temperature to a process temperature at a rate of between 25 and 100 ° C/min. If the heating rate of the spark plasma process is too slow, grain growth will occur during the sintering process, and the nanograin structure disappears. The pressure of the extruded multi-component thermoelectric alloy powder is between 25 MPa and 100 MPa. If the pressure of the extruded multi-component thermoelectric alloy powder is too low, the sintered density between the powders is lowered. If the pressure of the extruded multi-component thermoelectric alloy powder is too high, the grain structure in the sintered alloy has obvious directionality, and the alloy property is affected by the grain orientation.

The thermoelectric bulk material can be formed by the above ball milling process and the spark plasma sintering process. The process of the present invention has the following advantages:

(1) High alloying degree and uniformity: Since the binary alloy or other metal compound itself has no defects or voids and has high stability, it is difficult to cause impurities. After a high energy ball milling time of less than about 10 hours, a uniform multi-component thermoelectric alloy powder having a high degree of alloying can be obtained.

(2) Reducing the interaction between defects: High-energy ball milling process using binary alloys or other metal compounds can reduce the formation of internal defects and voids in the alloy, and reduce the chance of interaction between each other, avoiding excessive reverse carriers. To avoid reducing the conductivity.

(3) Nanostructure effect: In addition to alloying different compound powders, high-energy mechanical ball milling can also produce alloy powders with nano-grains. In combination with the current sintering technology, rapid sintering is carried out, that is, a pulse current is passed through the interface of the granules to form a high-energy plasma, which causes instantaneous rapid sintering. Rapid sintering removes oxides from the surface of the granules, forming a more complete interface and maintaining the nanocrystalline structure. Due to the current effect during sintering, nano-inclusions can precipitate in the grain boundaries or grains, and the quantum effect of the precipitated nano-inclusions can increase the Seebeck coefficient. The nanocrystals in the nanostructure and the nanograin boundary can also have a Scattering effect on the phonons, which can effectively reduce the heat transfer coefficient and further improve the thermoelectric efficiency.

(4) Process stability and energy saving benefits: Since the starting material is a compound powder, it has better stability, and is not easily lost due to high temperature in the ball milling and sintering process, which is beneficial to the control of the composition ratio and can increase the process stability. degree. Since the multi-component thermoelectric alloy powder is prepared by using different compound powders, the high-energy ball milling time is short, and the high-alloying degree powder can be obtained, and the rapid sintering technology can be used, and the sintering temperature can be lower than the conventional alloy melting process and high-temperature hot pressing method. At the same time, sintering can be completed in only a few minutes, so the overall process time can be greatly reduced, and the energy cost can be saved.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

[Examples]

Comparative Example 1 Bi _0.4 Sb _1.6 Te ₃ Alloy rod

Bi _0.4 Sb _1.6 Te ₃ alloy rod (made by alloy high temperature melting method) was crushed and placed in a ball mill tank, and ball milling process was carried out under argon to form a multi-component thermoelectric alloy powder with X-ray diffraction pattern. As shown in Figure 1. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 600 rpm, and the ball milling process lasts for 9 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 10 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The ZT value versus temperature curve of the last formed thermoelectric bulk material is shown in Fig. 2.

Example 1

4 mol parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mol of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form Bi _0.4 Sb. The X-ray diffraction pattern of _1.6 Te ₃ multi-component thermoelectric alloy powder is shown in Fig. 1. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 600 rpm, and the ball milling process lasts for 9 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 10 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The ZT value versus temperature curve of the last formed thermoelectric bulk material is shown in Fig. 2.

Example 2

4 mol parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mol of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form Bi _0.4 Sb. The X-ray diffraction pattern of _1.6 Te ₃ multi-component thermoelectric alloy powder is shown in Fig. 1. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 30:1, the ball milling speed is 600 rpm, and the ball milling process lasts for 9 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 10 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The ZT value versus temperature curve of the last formed thermoelectric bulk material is shown in Fig. 2.

As shown in Fig. 1, the crystal structure of the alloy powder obtained by ball milling alloying with Bi ₂ Te ₃ and Sb ₂ Te ₃ powders is consistent with the Bi _0.4 Sb _1.6 Te ₃ alloy rod structure and has good The degree of alloying.

Example 3

4 mol parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mol of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy. The powder has an X-ray diffraction pattern as shown in Fig. 1. The ball beads are stainless steel beads having a diameter of 3 mm, the volume ratio of the ball beads to the binary alloy is 30:1, the ball milling speed is 600 rpm, and the ball milling process lasts for 9 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 50 MPa. The ZT value versus temperature curve of the last formed thermoelectric bulk material is shown in Fig. 2.

As shown in FIG. 2, the ZT value of the thermoelectric bulk material of the embodiment of the present invention is superior to the ZT value of the thermoelectric bulk material of Comparative Example 1.

Comparative example 2

3 mole parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mole of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form Bi _0.5 Sb. _{The 1.5} Te ₃ multi-component thermoelectric alloy powder has an X-ray diffraction pattern as shown in Fig. 4A. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts for 3 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 350 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric block is shown in Fig. 3A, and its ZT value versus temperature curve is shown in Fig. 4.

Comparative example 3

3 mole parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mole of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form Bi _0.5 Sb. _1.5 Te ₃ multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts for 3 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric bulk material is shown in Fig. 3A. As for the two diffraction peaks shown in the enlarged view of the broken line frame 41 (Fig. 3B) of Fig. 3A, the degree of alloying of the low energy ball mill is insufficient.

Comparative example 4

3 mole parts of Sb ₂ Te ₃ (purchased from Alfa Aesar) and 1 mole of Bi ₂ Te ₃ (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form Bi _0.5 Sb. _1.5 Te ₃ multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts for 3 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 300 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The ZT value versus temperature curve of the finally formed thermoelectric bulk material is shown in Fig. 4. As shown in Fig. 4, the thermoelectric bulk material formed by the low-energy ball milling of the multi-component thermoelectric alloy powder after sintering of the spark plasma has a ZT value of only slightly higher than 0.4, which is much lower than that of the thermoelectric bulk material of the embodiment of the present invention. ZT value.

Comparative Example 5

3 mole parts of PbTe (purchased from Aldrich) and 1 mole of SnTe (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts 1 hour.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 300 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric bulk material is as shown in Fig. 5A.

Comparative Example 6

3 mole parts of PbTe (purchased from Aldrich) and 1 mole of SnTe (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the volume ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts 1 hour.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric bulk material is as shown in Fig. 5A.

Comparative Example 7

3 mole parts of PbTe (purchased from Aldrich) and 1 mole of SnTe (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the volume ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts for 3 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 300 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric bulk material is as shown in Fig. 5A.

Example 4

3 mole parts of PbTe (purchased from Aldrich) and 1 mole of SnTe (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts 6 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 300 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric block is shown in Fig. 5A, and a partial enlarged view of the X-ray diffraction pattern is shown in Fig. 5B.

Example 5

3 mole parts of PbTe (purchased from Aldrich) and 1 mole of SnTe (purchased from Alfa Aesar) were placed in a ball mill and subjected to a ball milling process under argon to form a multi-component thermoelectric alloy powder. The ball beads are stainless steel beads having a diameter of 3 mm, the weight ratio of the ball beads to the binary alloy is 20:1, the ball milling speed is 300 rpm, and the ball milling process lasts 6 hours.

Next, the multi-component thermoelectric alloy powder is placed in a sintering mold, and then the mold is placed on a molding machine for cold forming.

Then, the formed multi-component thermoelectric alloy powder is placed on a spark plasma sintering machine (SPS SYNTEX INC., DR. SINTER Model: SPS-511S), the sintering atmosphere is argon gas, the sintering temperature is 400 ° C, and the holding time is 5 minutes, the heating rate was between 100 ° C / min, and the pressure of the extruded multi-component thermoelectric alloy powder was 100 MPa. The X-ray diffraction pattern of the finally formed thermoelectric block is shown in Fig. 5A, and a partial enlarged view of the X-ray diffraction pattern is shown in Fig. 5B.

The embodiments of the present invention directly use different compound powders such as binary alloys for alloy preparation. Since the compound powder has higher stability than the pure element powder, a plurality of compound powders are alloyed by a high-energy ball milling process to form a multi-component thermoelectric alloy powder, and only a slight amount of component shift is generated, thereby avoiding the ball milling process. The problems caused, such as the interaction between the components and the defects. By controlling the parameters of the high-energy ball milling process, the stability and uniformity of the multi-component thermoelectric alloy powder can be increased, which is beneficial to the control of the alloy composition, and can shorten the time required for the process and contribute to the improvement of the alloying degree. The thermoelectric block of the embodiment of the present invention has the advantages of a maximum thermoelectric figure of merit (ZT value) of more than 0.4, a shortening of the ball milling process time, and a degree of alloying of the thermoelectric alloy powder.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

41. . . Dotted box

Figure 1 is an X-ray diffraction pattern of a multi-component thermoelectric alloy powder in a comparative example and an embodiment of the present invention;

Figure 2 is a graph of ZT value versus temperature for a thermoelectric bulk material in a comparative example and an embodiment of the present invention;

3A is a X-ray diffraction pattern of a multi-component thermoelectric alloy powder and a thermoelectric bulk material in a comparative example of the present invention;

Figure 3B is a partial enlarged view of Figure 3A;

Figure 4 is a graph of ZT value versus temperature for a thermoelectric bulk material in a comparative example of the present invention;

5A is an X-ray diffraction pattern of a thermoelectric bulk material in an embodiment and a comparative example of the present invention;

Fig. 5B is a partial enlarged view of Fig. 5A.

Claims (9)

A method for forming a multi-component thermoelectric alloy, comprising: placing a plurality of binary alloys and ball-milling beads in a ball-milling tank, performing a ball milling process to form a plurality of thermoelectric alloy powders, wherein the ball-beads have a diameter of between 1 mm and 10 mm. The weight ratio of the ball beads to the binary alloys is between 1:1 and 50:1, and the ball milling speed is between 200 rpm and 1000 rpm, and the ball milling process lasts 4 to 12 hours. The method for forming a multi-component thermoelectric alloy according to claim 1, wherein the dual alloys comprise a combination of Bi ₂ Te ₃ and Sb ₂ Te ₃ , and the multi-component thermoelectric alloy powder system Bi _x Sb _2-x Te ₃ , where x is between 0.1 and 0.8. The method for forming a multi-component thermoelectric alloy according to claim 1, wherein the dual alloys comprise a combination of Bi ₂ Te ₃ and Bi ₂ Se ₃ , and the multi-component thermoelectric alloy powder system Bi ₂ Se _y Te _{3- y} , where y is between 0.1 and 0.8. The method for forming a multi-component thermoelectric alloy according to claim 1, wherein the dual alloys comprise a combination of PbTe and SnTe, and the multi-component thermoelectric alloy powder system Pb _z Sn _1-z Te, wherein z is between 0.1 Between 0.9. The method for forming a multi-component thermoelectric alloy according to claim 1, wherein the dual alloy comprises a combination of PbTe and AgSb, a combination of PbAg and Sb ₂ Te ₃ , or a combination of PbSb and AgTe, and the multi-component thermoelectric Alloy powder system Ag _m Pb _n Te _p Sb, where m is between 0.1 and 1, n is between 15 and 25, and p is between 15 and 25. The method for forming a multi-component thermoelectric alloy according to claim 5, further comprising adding a metal compound to the ball mill tank, the metal compound comprising PbI ₂ , TeI ₄ , SbI ₂ , or AgI. The method for forming a multi-component thermoelectric alloy according to claim 6, wherein the binary alloy and the metal compound include PbAg, PbSb, a combination with TeI ₄ , a combination of PbAg, PbTe, and SbI ₂ , PbTe, PbSb, Combination with AgI, or AgTe, AgSb, and PbI ₂ , and the multi-component thermoelectric alloy powder system Ag _m Pb _n Te _p SbI _q , where m is between 0.1 and 1, and n is between 15 and 25. , p is between 15 and 25, and q is between 0.1 and 1. The method for forming a multi-component thermoelectric alloy according to claim 1, further comprising sintering and extruding the multi-component thermoelectric alloy powder under argon or vacuum in a spark plasma sintering process to form a thermoelectric block. The sintering temperature of the spark plasma process is between 300 ° C and 600 ° C, and the holding time is between 3 and 30 minutes. The method for forming a multi-component thermoelectric alloy according to claim 8, wherein the temperature rise rate of the spark plasma process is between 25 and 100 ° C / min, and the pressure of pressing the multi-component thermoelectric alloy powder is between Between 25MPa and 100MPa.