Low oxygen AlSc alloy powder and its manufacturing method

Abstract

The present invention relates to an AlSc alloy powder characterized by high purity and low oxygen content, as well as to a method for producing the same and its use in the electronics industry.

Description

[Technical Field]

[0001] The present invention relates to an AlSc alloy powder characterized by high purity and low oxygen content, as well as to a method for its production and its use in the electronics industry and in electronic components. [Background technology]

[0002] Scandium is classified as a rare earth metal and its demand continues to increase, especially in the context of ongoing developments in the fields of mobile communication technology, electric vehicles, and high-value aluminum alloys with special mechanical properties. As an alloying component, scandium is used together with aluminum, for example, as an AlScN dielectric layer in BAW (bulk acoustic wave) filters, in electronic components in the electronics industry, and for wireless transmission, such as WLAN and mobile communications. For this purpose, AlSc alloy powder or its elements are first prepared into AlSc sputter targets, which are then used to produce dielectric layers.

[0003] The fields of application in which AlSc alloy powder is used share a common requirement that the alloy powder must have high purity, which becomes difficult when handling scandium, which forms a natural oxide film in air. Furthermore, due to its very noble nature and high affinity for oxygen, scandium is difficult to produce in the form of a metal or alloy. Accordingly, there is a need for high-purity AlSc alloy powder and a method for producing the same.

[0004] Typically, AlSc alloys are obtained by reacting two metals together, where scandium can be produced in advance by reacting ScF with calcium. However, this method has the disadvantage that, after the simultaneous formation of a CaF slag, the scandium must be purified by sublimation at high temperatures. Nevertheless, significant amounts of impurities usually remain in the product, and the scandium is further contaminated by the crucible material due to the high temperatures required.

[0005] Furthermore, several preparation methods are known from the prior art, in which scandium chloride and aluminum react to give AlSc according to the following reaction scheme: ScCl3 + 4Al → Al3Sc + AlCl3.

[0006] The described preparation method has the drawback that, in addition to the high air and hydrolysis sensitivity of ScCl, several by-products, such as scandium oxide (ScO) or scandium oxychloride (ScOCl), are formed in addition to the target compound AlSc, as described by W. W. Endlandt, "The thermal decomposition of yttrium, scandium, and some rare-earth chloride hydrates," in J. Inorg. Nucl. Chem., 1957, Vol. 5, pp. 118-122. Thus, the decomposition of ScCl·6H0 leads to the formation of ScOCl and ScO. To address this drawback, several methods are known for producing anhydrous ScCl as pure as possible.

[0007] International Publication No. 1997 / 07057 (WO97 / 07057) describes a process for producing essentially pure and anhydrous rare earth metal halides by dehydration of their hydrated salts, in which the hydrated rare earth metal halides are introduced into a fluidized bed system having one reactor or multiple connected reactors, and a gaseous desiccant is added at elevated temperature to obtain rare earth halides having a specified maximum water content that are free from oxygen impurities, but does not mention contamination with oxychlorides.

[0008] European Patent Application Publication No. 0395472 (EP0395472) relates to dehydrated rare earth halides characterized by a water content of 0.01 to 1.5% by weight and an oxyhalide content of less than 3% by weight. The dehydration is achieved by passing a gas stream containing at least one dehydrated halide compound through a bed of the compound to be dehydrated at a temperature of 150 to 350°C. Dehydrated halide compounds include hydrogen halides, halogens, ammonium halides, carbon tetrachloride, S2Cl2, SOCl2, COCl2, and mixtures thereof. However, this document does not suggest that the described method is also suitable for producing scandium.

[0009] US Patent Application Publication No. 2011 / 0014107 (US2011 / 0014107) also discloses a method for producing anhydrous rare earth metal halides, which comprises forming a slurry from a rare earth halide hydrate and an organic solvent, heating the slurry under reflux, and finally distilling off water from the slurry.

[0010] Chinese Patent Application Publication No. 110540227 (CN110540227) describes a method for producing high-quality anhydrous rare-earth metal chlorides and bromides, which involves first pre-drying rare-earth metal halide hydrate REX3·xH2O to obtain REX3. The pre-dried product is treated in a vacuum under water- and oxygen-isolation conditions and gradually heated to 1500 °C, where REX3 is separated by sublimation from the co-produced oxide by-products. The rare-earth halides thus obtained have been demonstrated to have a purity of 99.99%. However, this method has the drawback of low yields, particularly for the production of ScCl3, because several oxide by-products, such as scandium oxide (Sc2O3) or scandium oxychloride (ScOCl), are formed during drying.

[0011] Even though methods for producing high purity starting compounds for producing AlSc alloys are known in the prior art, it has not yet been solved how to react them on an industrial scale to give the desired AlSc alloys while maintaining high purity.

[0012] In this regard, WO 2014 / 138813 discloses a method for producing an aluminum-scandium alloy starting from aluminum and scandium chloride, in which the scandium chloride is mixed with the aluminum and then heated to a temperature of 600-900 °C, and the resulting AlCl3 is removed by sublimation. In addition to the desired compound Al3Sc, the XRD pattern of the product (Figure 8) shows the formation of scandium metal and some impurities, Sc2O3, which, although not explicitly stated, can be identified by uncharacterized reflections at 2θ angles of 31.5° (Cu) and 33° (Cu).

[0013] Prior art methods have in common that they typically produce Al3Sc with a relatively high oxygen content and halide chlorine and / or fluorine content, which severely limits the potential applications of this powder. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] International Publication No. 1997 / 07057 [Patent Document 2] European Patent Application Publication No. 0395472 [Patent Document 3] US Patent Application Publication No. 2011 / 0014107 [Patent Document 4] Chinese Patent Application Publication No. 110540227 [Patent Document 5] International Publication No. 2014 / 138813 [Non-patent literature]

[0015] [Non-Patent Document 1] WWendlandt, "The thermal decomposition of Yttrium, Scandium, and some rare-earth chloride hydrates", veroeffentlicht in J.Inorg.Nucl.Chem.,1957, Vol.5, 118~122 Summary of the Invention [Problem to be solved by the invention]

[0016] Therefore, there remains a need for high-purity aluminum-scandium alloys (AlSc alloys) suitable for use in the electronics industry and mobile communication technology, as well as methods for their production. In view of this, it is an object of the present invention to provide such AlSc alloys suitable for the above applications. [Means for solving the problem]

[0017] Surprisingly, it has been found that this object is achieved by AlSc alloys which are characterized by a low content of oxygen and other impurities, in particular a low chloride and / or fluoride content.

[0018] Therefore, a first object of the present invention is to provide a crystalline silicon alloy having a purity of 99% by mass or more with respect to metallic impurities, and having a composition Al, as measured by X-ray fluorescence analysis (XRF), x Sc y wherein 0.1≦y≦0.9 and x=1−y, and the alloy powder has an oxygen content of less than 0.7% by weight, based on the total weight of the powder, as measured using carrier gas thermal extraction.

[0019] In certain embodiments, the alloy powder according to the present invention has the composition Al x Sc y[wherein 0.2≦y≦0.8, advantageously 0.24≦y≦0.7, each x=1−y]. Furthermore, the alloy powders may contain Al x Sc y Particularly preferably, the alloy powder according to the invention has the composition AlSc, where x=0.75, y=0.25, or AlSc, where x=2 / 3, y=1 / 3, and any mixtures of these compounds.

[0020] In a further preferred embodiment, the alloy powder according to the invention has a purity of 99.5% by weight or more, particularly preferably 99.9% by weight or more, with respect to each metallic impurity.

[0021] The powder according to the present invention is particularly characterized by its low oxygen content.Therefore, preferred embodiments are those in which the alloy powder has an oxygen content of less than 0.5% by weight, preferably less than 0.1% by weight, and particularly preferably less than 0.05% by weight, each based on the total weight of the powder.In this case, the oxygen content of the powder can be measured using carrier gas thermal extraction.

[0022] Surprisingly, it has been found that the powder according to the present invention is particularly suitable for applications requiring high purity.In addition to the low oxygen content, it has also been found that the powder has a low chloride content, which is essential for the electronics industry.Therefore, a preferred embodiment is that the alloy powder according to the present invention has a chlorine content of less than 1000 ppm, preferably less than 400 ppm, particularly preferably less than 200 ppm, and especially less than 50 ppm, as measured by ion chromatography.

[0023] Within the scope of the present invention, the designations "ppm" each indicate parts per million relative to the total mass of the powder.

[0024] In practice, metallic scandium, in particular, and oxide and halogen-containing impurities have been shown to cause difficulties in further processing, and these impurities can usually be detected by X-ray diffraction. These impurities include not only oxide impurities of scandium, such as ScO and ScOCl, but also oxide impurities introduced by the reaction partners used. Therefore, preferred embodiments of the present invention are those in which the X-ray diffraction pattern of the alloy powder according to the present invention does not contain reflections of compounds selected from the group consisting of ScO, ScOCl, ScCl, Sc, XScF, XScF, ScF, and other oxide impurities and fluoride heterophases (wherein X represents potassium or sodium ions). Other oxide impurities may be, for example, MgO, AlO, CaO, and / or MgAlO.

[0025] Furthermore, preferred are embodiments in which the alloy powder according to the invention has a magnesium content of less than 5000 ppm, advantageously less than 2500 ppm, particularly preferably less than 500 ppm, and especially less than 100 ppm, as measured by ICP-OES. In a further preferred embodiment, the alloy powder according to the invention has a calcium content of less than 5000 ppm, advantageously less than 2500 ppm, particularly preferably less than 500 ppm, and especially less than 100 ppm, as measured by ICP-OES. In a further preferred embodiment, the alloy powder according to the invention has a sodium content of less than 5000 ppm, advantageously less than 2500 ppm, particularly preferably less than 500 ppm, and especially less than 100 ppm, as measured by ICP-OES. Within the scope of the present invention, the terms "magnesium content," "sodium content," or "calcium content" include both elemental compounds and ions.

[0026] In a further preferred embodiment, the alloy powder according to the invention has a fluorine content, determined by means of ion chromatography, of less than 1000 ppm, advantageously less than 400 ppm, particularly preferably less than 200 ppm, in particular less than 50 ppm.

[0027] The alloy powder according to the invention is particularly suitable for further processing in the electronics industry, for example as a precursor to the production of sputter targets and dielectric layers produced therefrom, where a suitable particle size is also important in addition to high purity. Therefore, preferred embodiments are those in which the alloy powder has a particle size D90 of less than 2 mm, preferably 100 μm to 1 mm, particularly preferably 150 μm to 500 μm, as measured in accordance with ASTM B822-10. The D90 value of the particle size distribution represents 90% by volume of particles having a particle size equal to or less than the stated value.

[0028] A further subject of the present application is a method for producing an alloy powder according to the invention, comprising the steps of: mixing a scandium source and aluminum metal or an aluminum salt in the presence of a reducing agent to produce an Al x Sc y where 0.1≦y≦0.9, advantageously 0.2≦y≦0.8, particularly preferably 0.24≦y≦0.7, where x=1−y. According to the invention, the reducing agent is aluminum-free and different from aluminum or aluminum salts. The aluminum salts are preferably selected from the group consisting of XAlF, XAlF, AlF, and AlCl, where X represents a potassium or sodium ion. Surprisingly, it has been shown that the process according to the invention can avoid or significantly reduce the formation of undesired oxide impurities, making it possible to obtain AlSc alloy powders with high purity and low oxygen content.

[0029] While conventional production methods often require the use of ScCl3 or Sc metal as starting materials, which are difficult to prepare, the process according to the invention is characterized by the fact that the reaction can be carried out starting from scandium oxides and oxychlorides, as well as from ScCl3 contaminated with ScOCl and / or Sc2O3, thereby eliminating the need for the laborious dehydration or purification of the starting materials described in the prior art.Therefore, preferred embodiments of the process according to the invention are those in which the scandium source is selected from the group consisting of Sc2O3, ScOCl, ScCl3, ScCl3·6H2O, ScF3, X3ScF6, XScF4, and mixtures of these compounds, where X represents a potassium or sodium ion.

[0030] In particular, alkali metals and alkaline earth metals have proven to be suitable reducing agents in the process according to the invention. Thus, in a preferred embodiment, the reducing agent is selected from the group consisting of lithium, sodium, potassium, magnesium, and calcium, with sodium and potassium being used in particular in the case of the reaction of scandium fluorides, and magnesium and calcium being used in the case of the reaction of scandium chlorides. The use of the above reducing agents has the advantage that the oxidation products of the reducing agent formed during the reduction, such as MgO, MgCl2, and NaF, can be easily removed by washing. Therefore, preferred embodiments of the process further include a step of washing the resulting alloy powder. For example, distilled water and / or dilute mineral acids, such as H2SO4 and HCl, can be used to wash the powder.

[0031] It has been surprisingly shown that providing the reducing agent in vapor form can further reduce the introduction of impurities, and therefore embodiments in which the reducing agent is used in vapor form are preferred.

[0032] It has been found to be particularly effective when ScCl3, ScOCl and / or Sc2O3, or a mixture of these compounds, is used as the scandium source and reacted with aluminum metal and magnesium as the reducing agent. Surprisingly, it has been shown that the purity of the resulting AlSc alloy powder can be further increased if the aluminum metal and magnesium are pre-alloyed prior to the reaction. Thus, aluminum metal and magnesium are reacted in the form of an Al / Mg alloy with ScCl3, ScOCl and / or Sc2O3, or a mixture of these compounds, and Al x Sc y Preference is given to the embodiment of the process according to the invention in which x=1-y is reacted to: where 0.1≦y≦0.9, advantageously 0.2≦y≦0.8, particularly preferably 0.24≦y≦0.7.

[0033] It has proven particularly advantageous to use aluminum metal and / or Al / Mg alloys in the form of coarse powders, since this reduces the introduction of surface oxygen from these starting materials, thereby further reducing the oxygen content of the resulting alloy powder. Preferred embodiments are therefore those in which aluminum metal and / or Al / Mg alloys are present in the form of powders, with the powders advantageously having an average particle size D50 of more than 40 μm, preferably between 100 μm and 600 μm, and D90 of more than 300 μm, preferably between 500 μm and 2 mm, as measured according to ASTM B822-10, respectively. The D90 value of the particle size distribution indicates 90% by volume of the particles having a particle size equal to or less than the stated value, while the D50 value corresponds to 50% by volume of the particles having a particle size equal to or less than the stated value.

[0034] In a preferred embodiment, the method according to the invention is characterized in that it can be carried out at temperatures significantly lower than those customary in the prior art, thereby avoiding the inclusion of oxidized reducing agents, such as MgCl or MgO, in the alloy powder and thereby further increasing its purity. This is particularly true for the use of Al / Mg alloys, due to the decrease in melting point observed when alloying Al with Mg. Accordingly, a preferred embodiment of the method according to the invention is characterized in that the reaction is carried out at temperatures between 400 and 1050°C, preferably between 400 and 850°C, and particularly preferably between 400 and 600°C. The reaction time is preferably between 0.5 and 30 hours, more preferably between 1 and 24 hours.

[0035] In particular, when aluminum metal and magnesium are used with ScCl3 as the scandium source, it has been found to be advantageous if the reactants are evaporated separately and then combined in vapor form in the reaction chamber. In this way, oxide impurities of the precursors can be separated before reaction. Thus, ScCl3 and aluminum metal and magnesium are evaporated separately and then combined in vapor form in the reaction chamber to produce a compound of the composition Al x Sc y Preferred is the embodiment in which the reaction gives an alloy powder of the formula: [where 0.1≦y≦0.9, advantageously 0.2≦y≦0.8, particularly preferably 0.24≦y≦0.7, each x=1−y].

[0036] Surprisingly, it has been found within the scope of the present invention that the AlSc alloy powder according to the invention can also be obtained starting from a fluoride salt of scandium. Thus, a scandium fluoride salt and aluminum metal or aluminum salt are mixed in the presence of sodium or potassium to form a powder of the composition AlSc. x Sc yIn an alternative embodiment of the method according to the invention, the scandium fluoride salt is reacted to form an alloy powder of formula (where 0.1≦y≦0.9, advantageously 0.2≦y≦0.8, particularly preferably 0.24≦y≦0.7, where x=1−y), preferably from ScF, XScF, XScF, and any mixtures of these compounds, where X represents potassium or sodium, and mixtures thereof. Preferably, the aluminum salt is selected from the group consisting of AlF, XAlF, and XAlF, where X represents a potassium or sodium ion.

[0037] In this case, the reduction can be carried out using a mixed reducing agent or a vapor reducing agent. Furthermore, the reduction can also be carried out in the melt. The advantage of this option according to the present invention is that scandium fluorides, unlike chlorides, are stable in air or have low hygroscopicity and can be obtained by precipitation from aqueous solutions. This allows them to be handled in air, which greatly facilitates their use in industrial processes.

[0038] The method according to the invention allows the production of particularly pure AlSc alloy powders characterized by a low oxygen content. A further object of the invention is therefore to provide a method for producing AlSc alloy powders characterized by a low oxygen content, as determined by X-ray fluorescence analysis (XRD), with a composition of AlSc. x Sc y [wherein 0.1≦y≦0.9, preferably 0.2≦y≦0.8, particularly preferably 0.24≦y≦0.7, where x=1−y, respectively]. The powder thus obtained preferably has an oxygen content of less than 0.7% by weight, preferably less than 0.5% by weight, particularly preferably less than 0.1% by weight, and in particular less than 0.05% by weight, each based on the total weight of the powder and measured using carrier gas thermal extraction. Particularly preferably, the powder thus obtained has the above-mentioned properties.

[0039] The alloy powder according to the invention is characterized by a high purity and a low oxygen content, which makes it particularly suitable for use in the electronics industry. A further object of the invention is therefore the use of the alloy powder according to the invention in the electronics industry or in electronic components, in particular for producing sputter targets and BAW filters.

[0040] The present invention will be described in more detail using the following examples, which should not be construed as limiting the scope of the present invention in any way. [Brief explanation of the drawings]

[0041] [Figure 1] FIG. 1 shows the X-ray diffraction pattern of ScCl3 precursor P2. [Figure 2] FIG. 1 shows the X-ray diffraction pattern of ScCl3 precursor P3. [Figure 3] FIG. 10 is a diagram showing an X-ray diffraction pattern of the AlSc alloy powder according to Comparative Example C5. [Figure 4] FIG. 1 shows the X-ray diffraction pattern of the AlSc alloy powder according to Example E7 of the present invention. [Figure 5] FIG. 1 shows the X-ray diffraction pattern of AlSc alloy powder according to Example E13 according to the present invention. [Example]

[0042] 1. Preparation of the used scandium sources ScCl and ScOCl (precursors P1–P5) ScCl3 was prepared in the same manner as the conventional technique summarized in Table 1. ScCl3·6H2O (purity Sc2O3 / TREO 99.9%) available from Shinwa Bussan Co., Ltd. was used as the starting material.

[0043] P1: For P1, the reaction was carried out in a flow of argon at 720 °C for 2 h without the addition of NH4Cl.

[0044] P2: P2 is based on Example 2 of EP 0 395 472 A1, in which the corresponding Sc compound, ScCl 3 ·6H 2 O, was used instead of the NdCl 3 ·6H 2 O described therein.

[0045] P3: P3 is based on Example 5 of CN110540117A, in which the corresponding hydrate ScCl3·6H2O was used instead of the mixture of LaCl3·7H2O / CeCl3·7H2O described therein.

[0046] P4: For P4, pure phase ScOCl was used, which was prepared by heat treating ScCl3·6H2O in a quartz tube in a flow of HCl gas at 900 °C for 2 h without adding NH4Cl.

[0047] P5: Sc2O3 (purity Sc2O3 / TREO 99.9%) available from Shinwa Bussan Co., Ltd. was used as P5.

[0048] The phase composition determined by X-ray diffraction (XRD) for each product, as well as the oxygen content and residual content of H2O, are also shown in Table 1.

[0049] 2. Comparative Experiments C1 to C7 For comparative experiments C1 to C6, scandium-containing precursors P1 to P5 were mixed with aluminum or magnesium powder as shown in Table 2 and packed into a ceramic crucible. The aluminum powder used had an average particle size D50 of 520 μm, and the magnesium powder used had an average particle size D50 of 350 μm. Subsequently, thermal reactions were carried out in an argon atmosphere as shown in Table 2. Subsequently, each reaction product was washed with dilute sulfuric acid and dried in a convection drying cabinet for at least 10 hours, followed by chemical analysis and X-ray diffraction analysis. The results are also shown in Table 2.

[0050] For comparative experiment C7, Example 2 of WO 2014 / 138813 A1 was reproduced using precursor P3 (ScCl3) and aluminum powder with an average particle size D50 of 14 μm. After reaction under similar conditions as disclosed therein, a powder was obtained with the following characteristics: X-ray diffraction (XRD): Al3Sc Chemical analysis: Oxygen 0.81% by mass, Cl 15000ppm, F<50 ppm, Mg<10ppm, Na<10ppm, Ca<10ppm X-ray fluorescence analysis (XRF): Al:Sc ratio = 0.77:0.23 Particle size D50: 25μm The sum of all metal impurities (including Mg, Ca and Na) was determined to be <500 ppm for all experiments.

[0051] 3. Experiments according to the present invention a) E1~E8 Similar to comparative experiments C1-C7, for experiments E1-E8, scandium-containing precursors P1-P5 were mixed with powdered Al and Mg or Al / Mg alloy (69% Al, 31% Mg by weight) as shown in Table 3 and loaded into ceramic crucibles. The average particle size D50 of the aluminum powder used was 520 μm, the average particle size D50 of the magnesium powder was 350 μm, and the average particle size D50 of the Al / Mg alloy was 380 μm. The thermal reactions were carried out in a steel retort with argon flow for the entire reaction time as shown in Table 3. Subsequently, each reaction product was washed with dilute sulfuric acid and dried in a convection drying cabinet for at least 10 hours before being subjected to chemical analysis and X-ray diffraction analysis. The results are also shown in Table 3. For all experiments, the sodium and calcium contents were <10 ppm, respectively. The sum of all metal impurities (including Mg, Ca and Na) was determined to be <400 ppm for all experiments.

[0052] b) Experiments E9 to E34 Scandium- and aluminum-containing precursors were mixed in the ratios shown in Tables 3 and 4 and dispensed onto a finely perforated niobium plate. This was placed in a steel reduction vessel filled with sodium—the amount required for the reaction based on the stoichiometric ratio plus a 50% excess. The niobium plate was placed on top without direct contact with the sodium. The reaction was carried out in a steel retort through which argon was circulated for the entire reaction time. The sodium was evaporated, thereby reducing the precursors to elemental Sc and Al, which reacted in situ to the desired alloy.

[0053] After the reaction, the retort was carefully passivated with air, after which the steel reduction vessel was removed. Sodium fluoride formed during the reaction was washed off the reaction product with water, and the product was then dried at low temperature. The calcium content was <10 ppm and the sodium content was <50 ppm for all experiments. The sum of all metal impurities (including Mg, Ca, and Na) was measured to be <400 ppm for all experiments.

[0054] c) Experiments E35-E42 Scandium and aluminum-containing precursors were mixed (see Table 4) and placed in a niobium vessel with the amount of sodium required for the reaction based on the stoichiometry plus a 5% excess. The reaction was carried out in a steel retort with argon flowing through it for the entire reaction time. The precursors were reduced by sodium to elemental Sc and Al, which were then reacted in situ to form the desired alloy.

[0055] After the reaction, the retort was carefully passivated with air, after which the steel reduction vessel was removed. Excess sodium was dissolved by reaction with ethanol, and the remaining solids were washed with water. Sodium fluoride and / or sodium chloride were then washed off the reaction product, which was then dried at low temperature. The calcium content was <10 ppm and the sodium content was <50 ppm for all experiments. The sum of all metal impurities (including Mg, Ca, and Na) was measured to be <400 ppm for all experiments.

[0056] The oxygen content of the powders was determined by carrier gas thermal extraction (Leco TCH600), and the particle sizes D50 and D90 were determined by laser diffraction (ASTM B822-10, MasterSizer S, dispersion in water and Daxad 11, 5 min, sonication). Trace analysis of metal impurities was performed by ICP-OES (inductively coupled plasma optical emission spectroscopy) on the PQ 9000 (Analytik Jena) or Ultima 2 (Horiba) analyzers. The crystalline phase composition of powder samples was determined by X-ray diffraction (XRD) on a Malvern-PANalytical X'Pert-MPD Pro equipped with a semiconductor detector, a Cu LFF X-ray tube (40 kV / 40 mA), and a Ni filter. The determination of halides F and Cl was based on ion chromatography (ICS 2100). For X-ray fluorescence analysis (XRF, X Ray Fluorescence Spectroscopy) of Al and Sc, Malvern-PANalytical instruments Axios and PW2400 were used.

[0057] The percentages of each of the chemical elements are given in mass % and are relative to the total mass of the powder. The mass % purity for each metallic impurity is understood to be the ideal value of 100% minus the mass % of all investigated metallic impurities. The Al:Sc ratio is calculated from the Al and Sc contents measured using XRF.

[0058] The abbreviation TREO stands for the sum of the oxides of the rare earth elements.

[0059] [Table 1]

[0060] [Table 2]

[0061] [Table 3]

[0062] [Table 4-1]

[0063] [Table 4-2]

[0064] [Table 4-3]

[0065] As is evident from the data in Tables 3 and 4, the alloy powder according to the invention is not only characterized by a low oxygen content, but also by low chlorine and fluorine contents, which are not achieved by the methods known from the prior art. Furthermore, the presented experiments show that the method according to the invention allows the production of high-purity AlSc alloy powders, even starting from oxides, fluorides and chlorides of scandium, thus avoiding the need for complex post-treatment of the starting materials.

[0066] Figure 1 shows the X-ray diffraction pattern of the ScCl3 precursor P2.

[0067] Figure 2 shows the X-ray diffraction pattern of the ScCl3 precursor P3.

[0068] FIG. 3 shows the X-ray diffraction pattern of the AlSc alloy powder according to Comparative Example C5.

[0069] FIG. 4 shows the X-ray diffraction pattern of the AlSc alloy powder according to Example E7 of the present invention.

[0070] FIG. 5 shows the X-ray diffraction pattern of the AlSc alloy powder according to Example E13 of the present invention.

[0071] The two presented X-ray diffraction patterns of the AlSc alloy powders according to the invention are representative of all described experiments E1 to E42 according to the invention. As is evident from a comparison of the patterns provided, the patterns of the powders according to the invention do not show any additional reflections other than the desired AlSc target compound.

Claims

1. It has a purity of 99% by mass or more with respect to metal impurities and has the composition Al x Sc ｙ wherein 0.1≦y≦0.9 and x=1−y; the alloy powder having an oxygen content of less than 0.7% by weight, based on the total weight of the powder, as measured using carrier gas thermal extraction; a chlorine content of less than 200 ppm; and a fluorine content of less than 200 ppm, as measured using ion chromatography.

2. The X-ray diffraction pattern of the powder is Sc 2 O 3 , ScOCl, ScCl 3 , Sc, Al 2 O 3 , X 3 ScF 6 , XScF 4 , and ScF 3 2. The alloy powder according to claim 1, characterized in that it does not have reflections of compounds selected from the group consisting of: wherein X represents a sodium ion or a potassium ion.

3. 3. The alloy powder of claim 1, wherein the alloy powder has a magnesium content of less than 5000 ppm as measured by ICP-OES.

4. 4. The alloy powder according to claim 1, wherein the alloy powder has a particle size distribution D90 of less than 2 mm, measured according to ASTM B822-10.

5. 5. The method for producing the alloy powder according to claim 1, wherein a scandium source and aluminum metal or an aluminum salt are mixed in the presence of a reducing agent to form an Al x Sc y wherein 0.1≦y≦0.9, and each x=1−y.

6. The scandium source is Sc 2 O 3 , ScOCl, ScCl 3 , ScCl 3 ・6H 2 O, ScF 3 , X 3 ScF 6 and XScF 4 and mixtures of these compounds, wherein X represents a potassium ion or a sodium ion.

7. 7. The method according to claim 5 or 6, characterized in that the reducing agent is selected from the group consisting of magnesium, calcium, lithium, sodium and potassium.

8. aluminum metal and magnesium in the form of an Al / Mg alloy, the scandium source, and Al x Sc y 8. The method according to claim 5, wherein 0.1≦y≦0.9, and each x=1−y.

9. 9. The method of any one of claims 5 to 8, wherein the aluminium metal and / or the Al / Mg alloy is present in the form of a powder, the powder having an average particle size D50 greater than 40 μm and D90 greater than 300 μm as measured by ASTM B822-10.

10. Scandium fluoride salt and aluminum metal or aluminum salt are mixed in the presence of sodium or potassium to form a solution of the composition Al x Sc y 8. The method according to claim 5, wherein 0.1≦y≦0.9, respectively, x=1−y, to form an alloy powder.

11. 11. The method according to any one of claims 5 to 10, characterized in that the reaction is carried out at a temperature of from 400 to 1050°C.

12. Use of the alloy powder according to any one of claims 1 to 4 in the electronics industry, in electronic components.

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