Bismuth alloy composition and design method thereof

Abstract

The present invention relates to a bismuth alloy composition and a design method thereof. The alloy composition according to the present invention is an alloy composition comprising bismuth and a second element. The second element selected on the basis of an atomic radius difference between constituent atoms and mixing enthalpy is alloyed in an appropriate content according to a principle of improving liquid stability to provide an alloy composition satisfying a low melting point and a high degree of supercooling and exhibiting excellent flowability, which can be used as a liquid metal ion source.

Description

Bismuth alloy composition and design method thereof

[0001] The present invention relates to a bismuth alloy composition and a design method thereof.

[0002] Bismuth is a key material in strategic components used in low-melting-point alloys, metallurgical additives, pharmaceuticals, ferrite-type materials, and semiconductor compounds. In particular, bismuth alloys, as low-melting-point alloys, are used in various specialized applications. Recently, bismuth alloys with low melting points have been used as ion sources in mass spectrometers.

[0003] A liquid metal ion source (LMIS) is an ion source that heats metal to a liquid state and then forms ions through electrospray. It is used in many industrial fields because of its high current density, high brightness, and low energy spread. Recently, it has been focused on high-resolution ion beam lithography, ion implantation technology, and microfabrication technology. Most focused ion beam devices (FIBs) use liquid metal ion sources because their beam diameter is smaller and easier to handle than plasma ion sources. Most FIB devices have used LMIS using gallium, which has a low melting point, low vapor pressure, relatively non-reactive properties, and is heavy enough for ion milling, but LMIS using bismuth has also been utilized recently.

[0004] For bismuth-based alloys to be used in these LMIS applications, superior, customized properties such as low melting point, high supercooling, and flowability are required. However, research on bismuth alloy compositions suitable for ion beam applications that satisfy these properties remains insufficient.

[0005] The background technology described above is something that the inventor possessed or acquired in the process of deriving the disclosure of the present application, and cannot necessarily be said to be a publicly known technology disclosed to the general public prior to the present application.

[0006] The present invention aims to provide a bismuth alloy composition comprising bismuth and a second element to solve the above-described problem, and to provide a bismuth alloy composition having a low melting point, high supercooling, and high flowability, which can be used as a liquid metal ion source, by alloying bismuth with a second element that satisfies a large atomic radius difference and a small interatomic heat of mixing relationship.

[0007] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the relevant technical field from the description below.

[0008] An alloy composition according to the present invention comprises bismuth (Bi); and a second element (X); wherein the bismuth is at least 50 atomic% in the alloy composition, the second element satisfies the following calculation formulas 1 and 2, and the second element comprises at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In), which are elements capable of increasing liquid phase stability by being alloyed with the bismuth and undergoing a eutectic reaction, at less than 50 atomic%.

[0009] [Calculation Formula 1]

[0010] |(R Bi -R X ) / (R Bi )|≥0.07 (R Bi is the atomic radius of Bi, R X is the atomic radius of X)

[0011] [Calculation Formula 2]

[0012] ΔH Bi-X ≤4 (ΔH Bi-X is the mixing enthalpy of Bi and X, kJ / mol).

[0013] According to one embodiment, the second element may be characterized by having a temperature reducing ability of 1°C / at.% or more when added to the bismuth.

[0014] According to one embodiment, among the second elements, strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), lithium (Li), lead (Pb), tin (Sn), and indium (In) may be characterized by having a temperature reducing ability of 2°C / at.% or more when added to the bismuth.

[0015] According to one embodiment, among the second elements, strontium (Sr), manganese (Mn), gadolinium (Gd), lithium (Li), and lead (Pb) may be characterized by having a temperature reducing ability of 3°C / at.% or more when added to the bismuth.

[0016] According to one embodiment, among the second elements, strontium (Sr), manganese (Mn), and lithium (Li) may be characterized by having a temperature reducing ability of 4°C / at.% or more when added to the bismuth.

[0017] According to one embodiment, the alloy composition may include at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), and palladium (Pd) in an amount of less than 10 atomic percent, wherein the content of the second element, which alloys the bismuth and the second element to form a eutectic point, is within 10 atomic percent.

[0018] According to one embodiment, the alloy composition may include at least one of lithium (Li), sodium (Na), gold (Au), and gallium (Ga) in an amount of less than 40 atomic percent, wherein the content of the second element, which alloys the bismuth and the second element to form a eutectic point, is within a range of 10 to 40 atomic percent.

[0019] According to one embodiment, the alloy composition may include at least one of lead (Pb), tin (Sn), and indium (In) in an amount of less than 50 atomic percent, wherein the content of the second element, which alloys the bismuth and the second element to form a eutectic point, is in an amount of 40 atomic percent or more.

[0020] According to one embodiment, the alloy composition has a liquidus temperature of 271.3° C. or less, which is the melting point of a pure bismuth alloy, and the second element comprises strontium (Sr) in an amount of 3.2 atomic% or less, manganese (Mn) in an amount of 3 atomic% or less, gadolinium (Gd) in an amount of 1.5 atomic% or less, potassium (K) in an amount of 2.5 atomic% or less, erbium (Er) in an amount of 1.5 atomic% or less, zinc (Zn) in an amount of 9.5 atomic% or less, palladium (Pd) in an amount of 8.5 atomic% or less, lithium (Li) in an amount of 16.5 atomic% or less, sodium (Na) in an amount of 27 atomic% or less, gold (Au) in an amount of 18 atomic% or less, gallium (Ga) in an amount of 50 atomic% or less, lead (Pb) in an amount of 50 atomic% or less, It may contain less than 50 atomic% tin (Sn) or less than 50 atomic% indium (In).

[0021] According to one embodiment, the alloy composition may include manganese (Mn) as a second element in an amount of 7 atomic percent or less, and a temperature interval of a supercooling region of 25.5° C. or more, which is the supercooling temperature interval of pure bismuth.

[0022] According to one embodiment, the alloy composition may have a flow mass of 0.35 g or more, which is the flow mass of pure bismuth, as measured by copper mold flowability measurement, and may include manganese (Mn) as a second element in an amount of less than 5 atomic percent.

[0023] In one embodiment, the alloy composition may be used as a liquid metal ion source.

[0024] A design method of an alloy composition according to the present invention includes: a step of confirming a liquidus temperature and a eutectic point composition according to the content of the second element of an alloy composition including bismuth (Bi) and a second element (X); a step of grouping according to the content of the second element at the eutectic point indicating the lowest melting point of the alloy composition; a step of measuring supercooling of the alloy according to the type and content of the second element; and a step of measuring the flowability of the alloy according to the type and content of the second element.

[0025] According to one embodiment, the second element may be characterized by having a composition that exhibits a process reaction when alloyed with the bismuth.

[0026] According to one embodiment, the second element may be characterized by having an excellent temperature reduction ability of 1°C / at.% or more when added to the bismuth.

[0027] According to one embodiment, the step of confirming the liquidus temperature and the eutectic point composition according to the type and content of the second element may be confirmed through CALPHAD thermodynamic calculation.

[0028] According to one embodiment, the step of confirming the liquidus temperature and the eutectic point composition according to the content of the second element may be to confirm a composition in which the liquidus temperature of the alloy composition is 271.3°C or lower, which is the melting point of pure bismuth.

[0029] According to one embodiment, the grouping step may be grouping the second element into a first group in which the content of the second element alloyed with bismuth and having a eutectic point is less than 10 atomic%, a second group in which the content of the second element alloyed with bismuth and having a eutectic point is between 10 atomic% and less than 40 atomic%, a third group in which the content of the second element alloyed with bismuth and having a eutectic point is between 40 atomic% and less than 70 atomic%, and a fourth group in which the content of the second element alloyed with bismuth and having a eutectic point is 70 atomic% or more.

[0030] According to one embodiment, the step of measuring the supercooling comprises the steps of preparing an alloy composition according to the type and content of the second element; and measuring the supercooling of the alloy composition at the process melting point (T E h ) and the solidification point (T E c ) may include a step of measuring and confirming the difference.

[0031] According to one embodiment, the step of measuring the flowability may include: a step of preparing an alloy composition according to the type and content of the second element; and a step of measuring the flowability of the alloy composition under conditions in which a liquid phase melted by an arc plasma having a current of 1 A to 20 A is injected into a copper mold of 0.5 mm to 10 mm under a pressure of 0.01 MPa to 0.5 MPa.

[0032] The present invention can provide a bismuth alloy composition and a design method thereof.

[0033] Specifically, the bismuth alloy composition according to the present invention is an alloy composition comprising bismuth and a second element, wherein the second element selected based on the atomic radius and interatomic mixing enthalpy according to the principle of improving liquid phase stability is alloyed in an appropriate amount to provide an alloy composition that satisfies a low melting point and high supercooling and has excellent flowability, so that it can be provided as a liquid metal ion source.

[0034] Figure 1 is a drawing showing an ion source in which an alloy composition according to the present invention is used as a liquid metal ion source.

[0035] Figure 2 is an example of a Bi-Pd binary alloy phase diagram drawn using CALPHAD thermodynamic calculations.

[0036] Figures 3a to 3e show a Bi-X binary phase diagram drawn through CALPHAD thermodynamic calculations, and show a phase diagram of an alloy system including a composition in which the liquidus temperature of the alloy is lower than 271.3°C, the melting point of pure bismuth, through alloying.

[0037] Figure 4 shows a Bi-X binary phase diagram drawn through CALPHAD thermodynamic calculations, and shows a phase diagram of the Bi-Zr and Bi-Al alloy systems that do not include a composition in which the liquidus temperature of the alloy is lower than 271.3 ℃, the melting point of pure bismuth, through alloying.

[0038] Figure 5 shows the decrease in liquidus temperature compared to the addition amount of the second element in each group of the bismuth alloy composition according to the present invention.

[0039] Figure 6 shows a differential scanning calorimetry (DSC) curve measured during cooling of a Bi-Mn alloy, which is a bismuth alloy composition according to the present invention.

[0040] Figure 7 shows the results of measuring the supercooling (ΔT) of a Bi-Mn alloy, which is a bismuth alloy composition according to the present invention.

[0041] Figure 8 shows the results of measuring the flowability of a Bi-Mn alloy, which is a bismuth alloy composition according to the present invention.

[0042] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, the embodiments may be modified in various ways, and the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or alternatives to the embodiments are included within the scope of the patent application.

[0043] The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0044] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments pertain. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0045] In addition, when describing with reference to the attached drawings, the same components will be given the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. When describing an embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted. In addition, when describing a component of an embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only to distinguish the component from other components, and the nature, order, or sequence of the component is not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0046] Components included in one embodiment and components with common functions will be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in one embodiment can be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

[0047]

[0048] The alloy of the present invention satisfies a large atomic radius difference and a small heat of mixing between atoms among constituent elements, thereby providing a Bi alloy composition having a low melting point, high supercooling, and high flowability, so as to be suitable for use as a liquid metal ion source, with excellent liquid phase stability. In other words, by alloying pure Bi with a second element, an alloy having a lower liquidus temperature than the melting point of pure bismuth, an alloy having a greater supercooling than the supercooling of pure bismuth, or an alloy composition exhibiting a better flowability than the flowability of pure bismuth can be provided. The second element can theoretically have a large atomic radius difference from Bi or a relatively small heat of mixing between atoms to improve the liquid phase stability of the alloy.

[0049] In the alloy of the present invention, the melting point is the solidus temperature (T), which is the temperature at which the solid phase begins to change into a liquid phase. s h ) and the liquidus temperature (T), which is the temperature at which the solid completely changes into a liquid. l h ) can be distinguished. In addition, the crystallization onset temperature (T) of the alloy of the present invention s c) means the temperature at which the liquid phase starts to change into a solid phase during cooling. At this time, the difference between the solidus temperature and the solidification point is generally defined as the degree of supercooling (ΔT). However, in the case of a Bi-based alloy composition including a eutectic solidification reaction during cooling, the primary solidification reaction (primary crystallization) of the Bi phase and Bi compounds and other solidification reactions show a relatively very small phase change fraction compared to the eutectic solidification reaction, and the influence on the flowability and stability of the residual liquid may be significantly small. In particular, when the eutectic solidification reaction is included and the primary solidification phase is an ordered phase with high interfacial energy, the growth rate of the primary solidification phase is relatively slow. Therefore, in the alloys of the present invention, the degree of supercooling (ΔT) is the eutectic melting point (T ) regardless of the primary solidification reaction. E h ) and the solidification point (T E c ) can be expressed through the car.

[0050] The liquidus temperature and freezing point can be measured differently depending on the heating and cooling rate, and in the present invention, the heating and cooling rate can be 10 ℃ / min.

[0051]

[0052] The alloy composition according to the present invention is an alloy composition comprising bismuth (Bi); and a second element (X); wherein the bismuth forms a matrix and may be at least 50 atomic percent (at.%) in the alloy composition.

[0053] The alloy composition according to the present invention includes a binary Bi-X alloy composition comprising bismuth (Bi) and a second element (X).

[0054] Bismuth can be provided as a bismuth-based alloy composition to satisfy the required properties depending on the application. The alloy composition according to the present invention can provide an alloy that includes bismuth and has excellent properties such as a low melting point, high supercooling, and flowability, making it suitable for use as a liquid metal ion source.

[0055] If the above bismuth is less than 50 atomic%, the base element in the alloy may change, which may result in a decrease in Bi ionization efficiency, a decrease in the output of emitted Bi ions, or a problem in which the output of Bi ions is inhibited, preventing them from being generated consistently for a long period of time and reducing ion beam stability.

[0056]

[0057] According to one embodiment, the second element may form an alloy system including a eutectic point, which is an alloy composition that undergoes a eutectic reaction when alloyed with the bismuth.

[0058] The second element may be a metal element that can form an alloy with bismuth to improve liquid stability.

[0059] Preferably, the second element may include at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In).

[0060]

[0061] According to one embodiment, the second element may satisfy the following calculation formula 1.

[0062] [Calculation Formula 1]

[0063] |(R Bi -R X ) / (R Bi )|≥0.07 (R Bi is the atomic radius of Bi, R X is the atomic radius of X).

[0064] Equation 1 may be an equation calculated according to the stable liquid design principle, and has the advantage of increasing the stability of the liquid by promoting the formation of a dense packed structure by improving the packing ratio when the atomic radius difference between Bi and the second element is large by satisfying Equation 1, and forming an alloy with bismuth can reduce the melting point and maintain the supercooled liquid to a lower temperature during cooling, and exhibit excellent flow characteristics. Therefore, the larger the value of the atomic radius difference according to Equation 1, the higher the liquid stability, which is preferable. At this time, Equation 1 may be limited based on 7.1% of Sn, which has the smallest atomic radius difference among the second elements that are alloyed with Bi to form a eutectic point.

[0065] Preferably, the second element may include at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In).

[0066]

[0067] According to one embodiment, the second element may satisfy the following calculation formula 2.

[0068] [Calculation Formula 2]

[0069] ΔH Bi-X ≤4 (ΔH Bi-X is the mixing enthalpy of Bi and X, kJ / mol).

[0070] Equation 2 may be an equation calculated according to the stable liquid phase design principle, and when Equation 2 is satisfied and the mixing enthalpy between Bi and the second element is small, there is an advantage that the stability of the liquid phase can be increased by the attractive force between the constituent elements, and by forming an alloy with bismuth, the melting point can be reduced, the supercooled liquid phase can be maintained at a lower temperature during cooling, and excellent flow characteristics can be exhibited. Therefore, the smaller the mixing enthalpy between atoms according to Equation 2, the higher the liquid phase stability, which is preferable. At this time, Equation 2 can be limited based on 4 kJ / mol of Ga and Zn, which have the largest mixing enthalpy with Bi among the second elements that form a eutectic point by being alloyed with Bi.

[0071] Preferably, the second element may include at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In).

[0072]

[0073] In one embodiment, the second element may include less than 10 atomic percent of at least one selected from the first group consisting of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), and palladium (Pd).

[0074] The second element including at least one selected from the first group consisting of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), and palladium (Pd) may be an element in which the content of the second element having a eutectic point in the bismuth and second element alloy composition is less than 10 atomic%. Since the eutectic point generally indicates a relatively low temperature at which a thermodynamically stable liquid phase can be maintained in the alloy system, the composition near the eutectic point corresponds to a composition in which a liquid phase can exist at a relatively low temperature in terms of thermodynamics, and when an alloy is designed with a composition near the eutectic point, a low melting point, large supercooling, and thus excellent flowability can be exhibited. Since the Bi alloy including the first group of elements has a content of the second element forming the eutectic point of less than 10 atomic%, the Bi content can be maintained at 90 atomic% or more, thereby maximizing the beam output efficiency during Bi ionization.

[0075] When the content of the second element is 10 atomic% or more, the composition deviates significantly from the eutectic point that exhibits low melting point and supercooling in each alloy system, so that both compositions may have problems of reduced flowability due to a decrease in supercooling and an increase in the melting point (solidus temperature or liquidus temperature).

[0076]

[0077] In one embodiment, the second element may comprise less than 40 atomic percent of at least one selected from the second group consisting of lithium (Li), sodium (Na), gold (Au), and gallium (Ga).

[0078] The second element including at least one selected from the group consisting of lithium (Li), sodium (Na), gold (Au), and gallium (Ga) may be an element in which the bismuth and second element alloy composition has a eutectic point and the content of the second element exists in the range of 10 to 40 atomic%. The second element belonging to this second group may refer to an alloy group that can lower the melting point by inducing a eutectic reaction through alloying while maintaining the base of Bi.

[0079] When the content of the second element is 40 atomic% or more, the composition deviates significantly from the eutectic point that exhibits low melting point and supercooling in each alloy system, so both compositions may have problems of reduced flowability due to a decrease in supercooling and an increase in melting point.

[0080]

[0081] In one embodiment, the second element may include less than 50 atomic percent of at least one selected from a third group consisting of lead (Pb) and tin (Sn).

[0082] The second element including at least one selected from the group consisting of lead (Pb) and tin (Sn) may be an element in which the content of the second element, which has a eutectic point in the bismuth and second element alloy composition, is in the range of 40 to 70 atomic%. The second element belonging to this third group may refer to an alloy that lowers the melting point by undergoing a eutectic reaction at the boundary condition of the Bi matrix and the second element matrix. In this case, lead and tin may exhibit a characteristic of lowering the melting point when added even if the composition is not close to the eutectic point.

[0083]

[0084] In one embodiment, the second element may include indium (In), and the alloy composition may include indium in an amount of less than 50 atomic percent.

[0085] The second element including the above indium (In) may be an element in which the content of the second element having the eutectic point in the bismuth and second element alloy composition is in the range of 70 atomic% or more. The second element belonging to this fourth group may refer to an alloy that accompanies the eutectic reaction under the second element base condition and lowers the melting point. In particular, indium has a very low melting point, and thus, even if the composition is not close to the eutectic point, it can exhibit the characteristic of significantly reducing the melting point when alloyed.

[0086]

[0087] In one embodiment, the alloy composition may have a liquidus temperature of 271.3°C or lower. The melting point of pure bismuth is 271.3°C, and if the melting point of the Bi alloy is lower than this, it can be considered an alloy composition that has achieved a significantly low melting point due to the added element. Therefore, the composition range having a low melting point can be limited to cases in which the bismuth alloy has a liquidus temperature in the above range. In general, the lower the liquidus temperature of the alloy composition, the more stably the liquid phase can exist at a lower temperature, and thus, it may mean that the liquidus stability is high. In other words, if it has a liquidus temperature in the above range, it may exhibit a lower melting point compared to a single bismuth composition, and thus may have high liquidus stability, and may be suitable for utilizing the liquidus at a relatively lower temperature through alloying with a second element, and may exhibit characteristics suitable for utilization as a liquid metal ion source through excellent flowability that can be obtained through a wide supercooling region and low viscosity of the liquidus. Conversely, if the melting point exceeds the above range, a relatively higher temperature is required for beam output, which reduces process efficiency and may cause oxidation problems in various components of the ion beam generator. In addition, the relative flowability is reduced at the same temperature, which may cause problems in continuous transfer of the liquid alloy for stable ion beam emission from the storage to the ion beam tip.

[0088]

[0089] According to the examples of Table 2 and FIG. 3, the alloy composition maintains a Bi matrix in a Bi-X binary alloy system, and has a liquidus temperature lower than the melting point of pure bismuth, 271.3 ℃, strontium (Sr) of 3.2 at% or less, manganese (Mn) of 3 at% or less, gadolinium (Gd) of 1.5 at% or less, potassium (K) of 2.5 at% or less, erbium (Er) of 1.5 at% or less, zinc (Zn) of 9.5 at% or less, palladium (Pd) of 8.5 at% or less, lithium (Li) of 16.5 at% or less, sodium (Na) of 27 at% or less, gold (Au) of 18 at% or less, gallium (Ga) of less than 50 at% or It may contain less than 50 atomic% of lead (Pb), less than 50 atomic% of tin (Sn), and less than 50 atomic% of indium (In).

[0090] According to the comparative examples in Table 1 and Fig. 4, in the case of the second element zirconium (Zr), the difference in atomic radius with Bi is very small at 2.6%, which does not satisfy Equation 1, and does not form a composition showing a liquidus temperature lower than 271.3℃ through alloying. In addition, in the case of the second element aluminum (Al), the enthalpy of mixing with Bi is relatively large at 10, which does not satisfy Equation 2, and does not form a composition showing a liquidus temperature lower than 271.3℃ through alloying. In the cases of the second elements zirconium (Zr) and aluminum (Al), it can be seen that when the atomic radius and enthalpy of mixing with Bi do not satisfy Equations 1 and 2, it may not be possible to improve the liquidus stability of the alloy by reducing the liquidus temperature through alloying with Bi.

[0091] According to Fig. 5, for each element of Group 1 to Group 4 classified based on the content range of the second element forming the process point, the average decrease in liquidus temperature according to the amount added when alloying with Bi can be known. In detail, in Group 1, the order is Sr>Mn>Gd>K>Er>Zn>Pd, in Group 2, Li>Na>Au>Ga, and in Groups 3 and 4, Pb>In>Sn, showing a relatively excellent decrease in liquidus temperature relative to the amount added, which may be a useful element for improving the liquidus stability of Bi alloys. In particular, it can be confirmed that all elements of the present invention have an excellent temperature reduction ability of 1 ℃ / at.% or more when added to Bi, and in the case of Sr, Mn, Gd, K. Er, Zn, Li, Pb, Sn, In, it can be seen that they have a temperature reduction ability of 2 ℃ / at.% or more, in the case of Sr, Mn, Gd, Li, Pb, it can be seen that they have a temperature reduction ability of 3 ℃ / at.% or more, and in the case of Sr, Mn, Li, it can be seen that they have a temperature reduction ability of 4 ℃ / at.% or more.

[0092]

[0093] The phase transformation from liquid to solid requires undercooling to overcome the interfacial energy during the phase transformation, which means that the liquid exists at a temperature substantially lower than the thermodynamic equilibrium temperature. The temperature interval of the supercooled region (the degree of supercooling, ΔT) is the solidus temperature (T), which is the temperature at which the solid phase begins to change into the liquid phase thermodynamically. s h ) and the crystallization initiation temperature (freezing point, T) when the liquid is cooled s c) may mean the interval of the supercooling region. The larger the temperature interval of the supercooling region, the more excellent the liquid phase stability is. However, in the case of a Bi-based alloy composition including a eutectic solidification reaction during cooling, the primary solidification reaction (primary crystallization) of the Bi phase and Bi compounds and other solidification reactions show a relatively very small phase change fraction compared to the eutectic solidification reaction, and the influence on the flowability and stability of the residual liquid may be significantly less. In particular, when the eutectic solidification reaction is included and the primary solidification phase is a regular phase with high interfacial energy, the growth rate of the primary solidification phase is relatively slow. Therefore, in the alloys of the present invention, the supercooling (ΔT) is the eutectic melting point (T ) regardless of the primary solidification reaction. E h ) and the solidification point (T E c ) can be expressed through the car.

[0094] Figure 6 shows differential scanning calorimetry curves during liquid phase cooling of a Bi-Mn alloy according to Mn content. As can be seen in the figure, when Mn is added to Bi in amounts less than 10 atomic percent, the liquid phase crystallization initiation temperature (solidification point) is lowered compared to pure Bi.

[0095] Table 3 and Figure 7 show the solid-liquid phase transition temperature (eutectic melting point (T)) during heating and cooling of Bi-Mn alloys according to Mn content. E h ), liquidus temperature (T l h ), freezing point (T s c ), process freezing point (T E c )) and the calculated supercooling (ΔT) accordingly.

[0096] According to one embodiment, the alloy composition may be a Bi-Mn alloy including Mn as a second element at 7 atomic% or less, which exhibits excellent liquid phase stability by showing a temperature gap (ΔT) of a supercooling region of 25.5° C. or more, which is the width of the supercooling temperature region of pure bismuth.

[0097] According to one embodiment, the alloy composition may have a flow mass of 0.35 g or more, which is the flow mass of pure bismuth, as measured by the flowability measurement of a copper mold under conditions in which a liquid phase melted by an arc plasma of 1 A to 20 A current is injected into a 0.5 mm to 10 mm Cu mold under a pressure of 0.01 MPa to 0.5 MPa.

[0098] Flow mass can be measured by melting a bismuth binary composition liquid using an arc plasma having a current of 10 A, injecting it into a copper mold having a diameter of 1 mm at a pressure of 0.05 MPa, and measuring the weight (grams (g)) of the total alloy that flows during solidification. Conditions such as current, pressure, and mold diameter for measuring the flow mass can be adjusted according to the convenience of measurement and the fluidity of the alloy.

[0099] According to one embodiment of Table 3, the alloy composition may be a Bi alloy composition containing Mn in an amount of 7 atomic% or less and having a temperature gap in a supercooling region of 25.5°C or more, which is the supercooling degree of pure bismuth.

[0100] According to one embodiment of Table 3, the alloy composition may be a Bi alloy composition containing Mn in an amount of 5 atomic% or less and having a flow mass of 0.35 g or more, which is the flow mass of pure bismuth, as measured by a copper mold flowability measurement result.

[0101]

[0102] According to the example of Table 3 and Fig. 8, a Bi-Mn alloy composition containing Mn as a second element at 5 atomic% or less may exhibit excellent flowability as measured by flowability of a copper mold under the condition that a liquid phase melted by an arc plasma of 10 A current is injected into a 1 mm Cu mold at a pressure of 0.05 Pa, with a flow mass of 0.35 g or more, which is the flow mass of pure bismuth.

[0103] The above flowability value may vary if the flowability measurement method and conditions are different, and if the measurement method is different, the flowability can be determined through relative comparison by measuring under the same conditions as the bismuth single composition.

[0104]

[0105] In one embodiment, the alloy composition may be used as a liquid metal ion source.

[0106] In order to maximize the application effect of an alloy, it is necessary to use an alloy composition specialized for the purpose of application. A liquid metal ion source (LMIS) is used as an ion source that heats a metal in a focused ion beam device to make it into a liquid state and then forms ions through electrospray. Fig. 1 is a drawing showing an ion source in which an alloy composition according to the present invention is used as a liquid metal ion source. Referring to Fig. 1, the ion source includes two electrodes (12), a needle (15), and a disk base which is an electrical insulator. The electrode (12) is connected to the base and can receive current from a power source, and the electrode (12) can penetrate the base. The two electrodes (12) apply current to a filament (13), and the filament (13) can be formed of an alloy such as tungsten, INVAR, or KOVAR, and includes a connecting rod (131) and a support rod (132). The filament (13) is heated by the current applied from the electrode (12), and the heated filament (13) transfers heat to the liquid metal and needle (15) injected into the filament (13), and the liquid metal can be heated and melted in a solid state.

[0107] For use as a liquid metal ion source in the above ion source, flowability can be an important indicator. The alloy composition according to the present invention exhibits a low melting point, high supercooling, and superior flowability compared to a bismuth single composition, making it suitable as a liquid metal ion source.

[0108]

[0109] A design method of an alloy composition according to the present invention includes: a step of confirming a liquidus temperature and a eutectic point composition according to the content of a second element of an alloy composition including bismuth (Bi) and a second element (X); a step of grouping the alloy composition according to the content of the second element at the eutectic point indicating the lowest melting point of the alloy; a step of measuring supercooling of the alloy according to the type and content of the second element; and a step of measuring the flowability of the alloy according to the type and content of the second element.

[0110] To maximize the application effect of an alloy, it is necessary to specialize the alloy design strategy according to the application purpose. Therefore, in order to use a bismuth alloy composition as a liquid metal ion source, it is necessary to design an alloy composition that simultaneously satisfies complex properties such as low melting point, high supercooling, and excellent flowability. For a person skilled in the art, the optimal content that can secure the above properties is by no means easy to predict because it varies greatly depending on the type and amount of alloying elements. Therefore, deriving a content that can simultaneously obtain low melting point, high supercooling, and excellent flowability is very important. In order to provide a bismuth alloy composition that satisfies these properties, the present invention aims to provide a design method that limits the optimal element and composition range.

[0111]

[0112] In one embodiment, the second element may have a process reaction with the bismuth.

[0113] The step of identifying the second element having a process reaction with the above bismuth may include a step of comparing the atomic radius of the second element with the atomic radius of Bi; and a step of identifying the heat of mixing of the second element and Bi.

[0114] The second element may be an element that has a process reaction with bismuth, forms an alloy, and reduces the melting point, and may be an element that satisfies the stable liquid phase design principle. The second element may include at least one selected from the group consisting of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In).

[0115]

[0116] According to one embodiment, the step of confirming the process point may be to confirm the shape of the phase diagram and the liquidus temperature through CALPHAD thermodynamic calculation.

[0117] Since the second element can form a eutectic point by alloying with Bi, the formation of a eutectic point can be confirmed through CALPHAD calculations, allowing selection of the second element. The eutectic point composition corresponds to the composition at which the liquid phase can exist at the lowest temperature from a thermodynamic perspective. Furthermore, from a kinetic perspective, the simultaneous precipitation of complex phases can result in greater supercooling. Therefore, confirmation of the eutectic point is necessary to derive the optimal composition.

[0118] The above CALPHAD thermodynamic calculation utilizes a thermodynamic database for the constituent elements of each alloy system to calculate the equilibrium relationship between phases that can be formed at a given temperature, pressure, and composition, thereby deriving information on the most stable phase. Through the calculation, the alloy composition range in which the melting point can be lowered when bismuth is alloyed can be confirmed.

[0119]

[0120] According to one embodiment, the step of confirming the process point may be to confirm a composition in which the liquidus temperature of the alloy composition is 271.3°C or lower, which is the melting point of pure bismuth.

[0121] By verifying the process point, the composition range within which the liquidus temperature decreases can be identified. This can be used to verify the melting point to enhance the liquidus stability of the alloy composition, and the range of secondary element contents within the alloy composition with a liquidus temperature of 271.3°C or lower, which enhances liquidus stability, can be identified.

[0122]

[0123] According to one embodiment, the grouping step may be grouping the second element into a first group in which the content of the second element alloyed with Bi and having a eutectic point is less than 10 atomic %, a second group in which the content of the second element alloyed with Bi and having a eutectic point is between 10 atomic % and less than 40 atomic %, a third group in which the content of the second element alloyed with Bi and having a eutectic point is between 40 atomic % and less than 70 atomic %, and a fourth group in which the content of the second element alloyed with Bi and having a eutectic point is 70 atomic % or more.

[0124] The alloy composition can be divided into groups according to the content of the second element at the eutectic point indicating the lowest melting point, and the priority of the second element that can design an alloy of the eutectic point composition through alloying with the lowest content by grouping can be determined.

[0125] The first group has the characteristic that Bi-based alloys having a eutectic point composition can be designed by adding the smallest amount of less than 10 atomic percent, and the second group has the characteristic that Bi-based alloys having a eutectic point composition can be designed by adding a higher amount of 10 to 40 atomic percent. Utilizing the smallest amount of the second element can be advantageous in increasing the Bi content in the Bi alloy and in utilizing the properties of Bi in the liquid metal ion source. The third and fourth groups have the limitation that they can design alloys having a eutectic point only when adding very high amounts of 40 to 70 atomic percent and more than 70 atomic percent, respectively. However, on the other hand, since the melting points of the elements themselves are significantly low, they have the characteristic that the melting point of the alloy can be reduced in the entire composition range of the Bi alloy matrix without designing an alloy having a eutectic point composition or a composition near the eutectic point. Accordingly, for the design of Bi alloys, elements of the first group can be considered as additive elements first, and in some cases, elements of the second to fourth groups can also be considered as additive elements.

[0126]

[0127] According to one embodiment, the steps of preparing an alloy composition according to each group; confirming a composition in which the liquidus temperature of the alloy composition is lower than or equal to 271.3° C., which is the melting point of pure bismuth; and supercooling the alloy composition to a process melting point (T E h ) and the solidification point (T E c) and a step of confirming the flow mass by measuring the flowability of the copper mold; In detail, in the step of preparing the alloy composition according to each group, an alloy composition according to the content of the second element limited by theory or thermodynamic calculation can be prepared. In addition, in the step of confirming the composition in which the liquidus temperature of the alloy composition is 271.3 ℃ or lower, which is the melting point of pure bismuth, the liquidus temperature of the prepared alloy composition can be measured to confirm the content range of the second element having a lower liquidus temperature than the melting point of pure bismuth. In addition, the supercooling of the alloy composition can be determined by the process melting point (T E h ) and the solidification point (T E c ) is measured and confirmed, the actual supercooling of the prepared alloy composition can be measured to confirm the content range of the second element having a large temperature gap in the supercooling region compared to the pure bismuth composition. Finally, the flowability of the alloy composition with confirmed supercooling can be analyzed to derive the composition range of the bismuth binary alloy composition having high flowability compared to the pure bismuth composition. That is, through the three steps of theory, thermodynamic calculation, and experiment, the optimal composition range of the alloy composition can be derived, which can include a composition exhibiting liquid stability to a composition having excellent flowability. Accordingly, a bismuth alloy composition having excellent liquid stability in which both supercooling and flowability are improved is provided, so that it can be used as a liquid metal ion source.

[0128]

[0129] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples.

[0130] However, the following examples are only intended to illustrate the present invention, and the content of the present invention is not limited to the following examples.

[0131]

[0132] Example

[0133] In order to manufacture a Bi-X bismuth alloy composition, the composition ratio of bismuth and a second element was derived.

[0134] First, in order to select a second element that reduces the liquidus temperature by alloying with bismuth, the atomic radius, the difference in atomic radius with Bi, and the enthalpy of mixing with Bi were confirmed for each element according to the alloy stable liquidus design principle, and the results are shown in Table 1 below.

[0135] Element (X)Atomic radius (pm)Atomic radius difference from Bi (%)Heat of mixing with BiΔH (Bi-X, kJ / mol)Bi156--Sr21537.8-61Mn127-18.63Gd18015.4-54K22745.5-24Er17612.8-52Zn135-13.54Pd137-12.2-21L i145-7.1-23Na18619.2-20Au144-7.72Ga135-13.54Pb18015.40Sn140-10.31In1677.1-1Zr1602.6-40Al143-8.310

[0136] Referring to Table 1 above, other elements than Zr and Al satisfy both Calculation Equation 1 and Calculation Equation 2, and by comparing the atomic radius difference and mixing enthalpy between each second element and Bi, the second element that can form a stable liquid phase when alloying the second element can be limited.

[0137] Afterwards, the eutectic point of the Bi-X alloy composition was confirmed through CALPHAD thermodynamic calculation. Fig. 2 is an example of a Bi-Pd phase diagram drawn through a thermodynamic calculation of a design method of a bismuth alloy composition according to the present invention. Referring to Fig. 2, the thermodynamic calculation result according to the palladium content of the Bi-Pd (bismuth and palladium) alloy composition, which is one of the Bi-X alloy compositions, can be confirmed, and it can be confirmed that the eutectic point is formed in a composition having a Pd content of about 7.5 atomic%. Figs. 3a to 3e show a Bi-X binary phase diagram drawn through a thermodynamic calculation of a design method of a bismuth alloy composition according to the present invention, and show a phase diagram of an alloy system including a composition (shaded area) in which the liquidus temperature of the alloy is lower than 271.3 ℃, which is the melting point of pure bismuth, through alloying.

[0138] FIG. 4 shows a Bi-X binary phase diagram drawn through thermodynamic calculation of a design method of a bismuth alloy composition according to the present invention, and shows a phase diagram of Bi-Zr and Bi-Al alloy systems that do not include a composition in which the liquidus temperature is lower than 271.3 ℃, which is the melting point of pure bismuth, through alloying with a second element to Bi. As can be seen in the drawing, when Zr and Al, whose atomic radius difference and mixing enthalpy conditions with Bi do not satisfy Equations 1 and 2, are added, it can be seen that the liquidus temperature is not reduced through alloying with Bi, and thus the liquidus stability of the alloy is not improved.

[0139] Figure 5 shows the liquidus temperature decrease amount compared to the addition amount of the second element in each group of the bismuth alloy composition according to the present invention. As shown in the figure, in group 1, the order is Sr>Mn>Gd>K>Er>Zn>Pd, in group 2, Li>Na>Au>Ga, and in groups 3 and 4, Pb>In>Sn, showing a relatively excellent liquidus temperature decrease amount compared to the addition amount, and thus, it can be a useful element for improving the liquidus stability of Bi through alloying. In particular, it can be confirmed that all elements of the present invention have an excellent temperature reduction ability of 1 ℃ / at.% or more when added to Bi, and in the case of Sr, Mn, Gd, K. Er, Zn, Li, Pb, Sn, In, it can be seen that they have a temperature reduction ability of 2 ℃ / at.% or more, in the case of Sr, Mn, Gd, Li, Pb, it can be seen that they have a temperature reduction ability of 3 ℃ / at.% or more, and in the case of Sr, Mn, Li, it can be seen that they have a temperature reduction ability of 4 ℃ / at.% or more.

[0140]

[0141] Table 2 below shows the second element content of alloys in the Bi-X binary alloy system defined in Table 1 above, whose liquidus temperature is lower than 271.3°C, the melting point of pure bismuth.

[0142] X content (at.%)Sr0 ~ 3.2Mn0 ~ 3Gd0 ~ 1.5K0 ~ 2.5Er0 ~ 1.5Zn0 ~ 9.5Pd0 ~ 8.5Li0 ~ 16.5Na0 ~ 27Au0 ~ 18Ga0 ~ 100Pb0 ~ 81Sn0 ~ 100In0 ~ 100

[0143] Based on the results of Table 2 and Figures 3a to 3e above, an alloy composition including a composition range in which the liquidus temperature of the Bi-X alloy is lower than the melting point of pure bismuth, 271.3 ℃, was manufactured and the melting point and supercooling were analyzed. Table 3 below shows the eutectic solidification point (T of the Bi-Mn alloy composition, which is one of the Bi-X alloy compositions of the present invention. E c ), process melting point (T Eh ), supercooling, and flowability are analyzed. In this case, pure Bi has a freezing point (T ) due to the absence of a eutectic point. s c ) and liquidus temperature (T l h ) was used to measure the degree of supercooling.

[0144]

[0145] BiMn process solidification point (T E c , ℃) melting point (T E h , ℃) Supercooling (ΔT (℃)) Flowability (Flow mass (g)) 10245.9 (Replaced by solidification point due to absence of process point (T s c ))271.4(Substitute liquidus temperature for absence of process point (T l h ))25.50.350.9780.022235.1264.529.40.360.960.04228.7264.535.80.540.940.06236.7265.128.40.280.920.08244.0265.121.10.220.90.1246.6265.118.50.200.850.15247.1265.118.00.160.80.2247.9265.117.20.13

[0146] FIG. 6 and FIG. 7 are DSC measurement results, in which FIG. 6 shows a heat flow curve when the Bi-Mn alloy, which is a bismuth alloy composition according to the present invention, is cooled from a liquid phase, and FIG. 7 shows the supercooling measurement results of the Bi-Mn alloy, which is a bismuth alloy composition according to the present invention. Referring to FIG. 6 and FIG. 7, the change in the solidification point and the degree of supercooling according to the content (at.%) of Mn can be known, and through FIG. 6, when less than 10 atomic% of Mn is added to Bi, the solidification point is lower than that of Bi, and when 7 atomic% or less of Mn is added to Bi, the degree of supercooling becomes greater than that of Bi. Through these results, it is possible to limit a Bi-Mn composition that simultaneously satisfies the low melting point and high supercooling conditions.

[0147] Fig. 8 shows the flow mass (g) obtained by flow measurement under the condition that the liquid phase melted by the arc plasma of 10 A current of Bi-Mn, a bismuth alloy composition according to the present invention, is injected into a 1 mm Cu mold by a pressure of 0.05 Pa. Referring to Fig. 8, it can be confirmed that the composition range of manganese (Mn) in which the flowability increases compared to pure bismuth depending on the manganese (Mn) content, and it can be confirmed that when less than 5 atomic% of Mn is added to Bi, the flowability is superior to that of Bi.

[0148] Accordingly, it can be confirmed that the alloy composition provided by the alloy composition design method according to the present invention can provide a bismuth alloy composition having an optimal composition range, thereby exhibiting a low melting point, high supercooling, and excellent flowability.

[0149]

[0150] Although the embodiments have been described above, those skilled in the art will appreciate that various technical modifications and variations can be applied based on the above. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0151] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. Bismuth (Bi); and An alloy composition comprising a second element (X); The above bismuth is at least 50 atomic% of the alloy composition, The above second element satisfies the following calculation formulas 1 and 2, The second element comprises at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), palladium (Pd), lithium (Li), sodium (Na), gold (Au), gallium (Ga), lead (Pb), tin (Sn), and indium (In), which are elements that can increase liquid stability by alloying with the bismuth and causing a process reaction, at less than 50 atomic%. alloy composition, [Calculation Formula 1] |(R Bi -R X ) / (R Bi )|≥0.07 (R Bi is the atomic radius of Bi, R X is the atomic radius of X) [Calculation Formula 2] ΔH Bi-X ≤4 (ΔH Bi-X is the mixing enthalpy of Bi and X, kJ / mol).

2. In paragraph 1, The second element is characterized in that it has a temperature reducing ability of 1 ℃ / at.% or more when added to the bismuth. Alloy composition.

3. In paragraph 2, Among the second elements, strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), lithium (Li), lead (Pb), tin (Sn), and indium (In) are characterized in that they have a temperature reducing ability of 2 ℃ / at.% or more when added to the bismuth. Alloy composition.

4. In paragraph 2, Among the second elements, strontium (Sr), manganese (Mn), gadolinium (Gd), lithium (Li), and lead (Pb) are characterized in that they have a temperature reduction ability of 3 ℃ / at.% or more when added to the bismuth. Alloy composition.

5. In paragraph 2, Among the second elements, strontium (Sr), manganese (Mn), and lithium (Li) are characterized in that they have a temperature reduction ability of 4 ℃ / at.% or more when added to the bismuth. Alloy composition.

6. In paragraph 1, The alloy composition comprises at least one of strontium (Sr), manganese (Mn), gadolinium (Gd), potassium (K), erbium (Er), zinc (Zn), and palladium (Pd) in an amount of less than 10 atomic%, wherein the content of the second element, which forms a eutectic point by alloying the bismuth and the second element, is within 10 atomic%. Alloy composition.

7. In paragraph 1, The alloy composition comprises at least one of lithium (Li), sodium (Na), gold (Au), and gallium (Ga) in an amount of less than 40 atomic%, wherein the content of the second element, which forms a eutectic point by alloying the bismuth and the second element, is within a range of 10 to 40 atomic%. Alloy composition.

8. In paragraph 1, The alloy composition comprises at least one of lead (Pb), tin (Sn), and indium (In) in an amount of less than 50 atomic%, wherein the content of the second element, which forms a eutectic point by alloying the bismuth and the second element, is in an amount of 40 atomic% or more. Alloy composition.

9. In paragraph 1, The above alloy composition has a liquidus temperature of 271.3°C or lower, which is the melting point of a pure bismuth alloy. The second element comprises strontium (Sr) in an amount of 3.2 atomic% or less, manganese (Mn) in an amount of 3 atomic% or less, gadolinium (Gd) in an amount of 1.5 atomic% or less, potassium (K) in an amount of 2.5 atomic% or less, erbium (Er) in an amount of 1.5 atomic% or less, zinc (Zn) in an amount of 9.5 atomic% or less, palladium (Pd) in an amount of 8.5 atomic% or less, lithium (Li) in an amount of 16.5 atomic% or less, sodium (Na) in an amount of 27 atomic% or less, gold (Au) in an amount of 18 atomic% or less, gallium (Ga) in an amount of less than 50 atomic%, lead (Pb) in an amount of less than 50 atomic%, tin (Sn) in an amount of less than 50 atomic%, or indium (In) in an amount of less than 50 atomic%. Alloy composition.

10. In paragraph 1, The above alloy composition has a temperature interval of the supercooled region of 25.5°C or more, which is the supercooled temperature interval of pure bismuth. Containing manganese (Mn) as a second element in an amount of 7 atomic% or less, Alloy composition.

11. In paragraph 1, The above alloy composition has a flow mass of 0.35 g or more, which is the flow mass of pure bismuth, as measured by copper mold flowability, Containing manganese (Mn) as a second element in an amount of less than 5 atomic percent, Alloy composition.

12. In paragraph 1, The above alloy composition is used as a liquid metal ion source, Alloy composition.

13. An alloy composition containing bismuth (Bi) and a second element (X) A step of confirming the liquidus temperature and eutectic point composition according to the content of the second element; A step of grouping according to the content of the second element at the eutectic point indicating the lowest melting point of the alloy composition; A step of measuring the supercooling of the alloy according to the type and content of the second element; and A step of measuring the flowability of an alloy according to the type and content of the second element; including, Design method of alloy composition.

14. In paragraph 13, The second element is characterized in that it has a composition that exhibits a process reaction when alloyed with the bismuth. Design method of alloy composition.

15. In paragraph 13, The second element is characterized in that it has a temperature reducing ability of 1 ℃ / at.% or more when added to the bismuth. Design method of alloy composition.

16. In paragraph 13, The step of confirming the liquidus temperature and eutectic point composition according to the type and content of the second element is to confirm through CALPHAD thermodynamic calculation. Design method of alloy composition.

17. In paragraph 13, The step of confirming the liquidus temperature and the eutectic point composition according to the content of the second element is to confirm the composition in which the liquidus temperature of the alloy composition is 271.3 ℃ or lower, which is the melting point of pure bismuth. Design method of alloy composition.

18. In paragraph 13, The above grouping steps are: The second element is grouped into a first group in which the content of the second element alloyed with bismuth and having a eutectic point is less than 10 atomic%, a second group in which the content of the second element alloyed with bismuth and having a eutectic point is from 10 atomic% to less than 40 atomic%, a third group in which the content of the second element alloyed with bismuth and having a eutectic point is from 40 atomic% to less than 70 atomic%, and a fourth group in which the content of the second element alloyed with bismuth and having a eutectic point is 70 atomic% or more. Design method of alloy composition.

19. In paragraph 13, The step of measuring the above supercooling is: A step of preparing an alloy composition according to the type and content of the second element; supercooling the alloy composition to a process melting point (T E h ) and the solidification point (T E c ) including a step of measuring and confirming the difference; Design method of alloy composition.

20. In paragraph 13, The step of measuring the above flowability is: A step of preparing an alloy composition according to the type and content of the second element; and a step of measuring the flowability of the alloy composition under conditions in which a liquid phase melted by an arc plasma of a current of 1 A to 20 A is injected into a copper mold of 0.5 mm to 10 mm under a pressure of 0.01 MPa to 0.5 MPa. Design method of alloy composition.

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