CN1436625A

CN1436625A - Direct prepn of Dy-Fe alloy powder with metal oxide

Info

Publication number: CN1436625A
Application number: CN 02102294
Authority: CN
Inventors: 徐军
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-06
Filing date: 2002-02-06
Publication date: 2003-08-20

Abstract

The present invention is the preparation process of Fe2Dy alloy powder as one intermetallic compound. The Fe2Dy alloy powder with Dy content of 30-60 wt% is prepared through direct reduction and diffusion process of two kinds of metal oxides Dy2O3 and Fe2O3 in the presence of Ca as reductant. Compared with available technology, the metal calcium reduced metal Dy and metal Fe in nascent atom mode form intermetallic compound Fe2Dy immediately, and this results in shortened period of reduction and diffusion, homogeneous alloy structure, no environmental pollution, low cost and stable alloy components. The said alloy powder may be used widely in permanent magnetic material, magneto-optical material and magnetostriction material.

Description

Dy-Fe alloy powder directly prepared from metal oxide

Technical Field

The invention relates to a method for preparing intermetallic compound type alloy, in particular to a method for preparing dysprosium-iron intermetallic compound, belonging to the technical field of new materials.

Background

Dy-Fe (Fe)₂Dy) alloy has special physical and chemical properties, so that the Dy) alloy is widely applied to various functional materials, and particularly becomes a necessary additive in a high-performance rare earth permanent magnet material (NdFeB), thereby remarkably improving the magnetic performance of the rare earth permanent magnet material. The current addition amount reaches 2 to 4 percent of the weight of the rare earth giant magnetostrictive material (Fe)_1.95Dy_0.7，Tb_0.3) The dysprosium is about 40 wt%, the metal dysprosium is also the main alloy element of the magneto-optical storage material (FeDyTbGa), the content of the metal dysprosium reaches about 40%, and the recording density of the material is high and is almost 50 times that of a hard magnetic disk and 1000 times that of a soft magnetic disk. Therefore, the development prospect is very wide.

In the smelting process of the materials, the alloy elements are almost added in the form of pure metals, and according to the smelting principle, the alloy elements are added in the form of master alloy (intermediate alloy) rather than in the form of pure metalsMore reasonable because the melting point of the master alloy is lower than that of pure metal (Fe)₂The melting point of Dy alloy is 1270 deg.C, and the melting point of pure metal dysprosium is greater than 1500 deg.C), so that the mother alloy is easy to melt quickly when smelting practical alloy, and the alloy components are more uniform, thus saving smelting time, reducing cost and reducing unnecessary loss of alloy.

In the current practical application, besides the application of the alloy element dysprosium in the form of pure metal, the alloy element dysprosium is also applied in the form of dysprosium-iron alloy containing dysprosium instability, the pure metal dysprosium is prepared by rare earth fluoride through a calcium thermal reduction method, the dysprosium-iron alloy is prepared by co-melting pure metal dysprosium and metal iron into dysprosium-iron alloy containing more than 70% of dysprosium, or the dysprosium-iron alloy containing more than 90% of dysprosium is prepared by an electrolytic method. The preparation of pure dysprosium by using rare earth fluoride has the disadvantages of increasing cost and serious environmental pollution, such as high production cost by smelting dysprosium and iron together, and the dysprosium-iron alloy prepared by adopting an electrolytic method has unstable dysprosium content and brings difficulty to practical use.

If Fe is used₂O₃And Dy₂O₃The mixture reacts with hydrofluoric acid to prepare Dy and Fe fluorides of goldBelongs to a thermal reduction method for preparing Dy-Fe alloy, and has high cost and serious environmental pollution.

Disclosure of Invention

The invention aims to provide a new production process technology, thereby effectively overcoming the defects of complex process, serious environmental pollution and high production cost of the prior related technology in the preparation method of the dysprosium-iron alloy.

The invention adopts a calcium reduction diffusion method to directly prepare the metal oxide (Fe)₂O₃，Dy₂O₃) Production (preparation) of Fe₂The key technology to be solved for Dy intermetallic compound powder is the reduction diffusion process parameter.

The technical scheme adopted by the invention for solving the technical problems is as follows: dosage of reducing agent (calcium), reduction and diffusion reaction time and retention timeThe influence of the contents of dysprosium (Dy) and iron (Fe) was experimentally measured. The scientific principle is that according to the binary equilibrium state diagram of Fe-Dy, Fe with the melting point of 1270 ℃ can be formed when the content of dysprosium reaches 59 percent (by weight)₂Dy intermetallic compounds. Based on rare earth oxides (Dy)₂O₃) And iron oxide (Fe)₂O₃) The free energy of the generated reaction can judge the adopted reducing agent and the temperature of the reduction reaction, and the heat preservation time of the diffusion reaction can be judged according tothe kinetic reaction principle.

The chemical reaction equation for preparing Dy-Fe alloy powder by reduction diffusion method is:

according to the above reaction, the theoretical amount of each reactant is calculated by first uniformly mixing the two metal oxide powders and the calcium metal chips or calcium granules for at least one hour by using a mixer, and then uniformly mixing the mixture in a press machine at 500kg-550kg/cm²Pressing into blocks of certain shape under pressure, and performing reduction diffusion reaction in a vacuum resistance furnace under the protection of argon to obtain Dy-Fe alloy powder with different Dy contents, wherein the Dy content in the alloy powder can be changed within 30-60 wt% as required, and when the Dy content reaches 59%, the alloy is Fe₂Dy intermetallic compounds, otherwise alloys with Fe₂Dy intermetallic compound and iron. The reduction reaction temperature is 900-1100 ℃, the temperature holding time is 1-2 hours, the diffusion reaction temperature is 1100-1200 ℃, the temperature holding time is 2-3 hours, and after the reaction is finished, the reaction material is slowly cooled or quenched to 30-50 ℃. Crushing the sample into particles smaller than 5mm, soaking in water, stirring, standing, removing turbid liquid, washing with water repeatedly until there is no white suspended matter in water, and adding 2% NH₄And (3) washing the alloy powder for 3-4 times by using a mixed aqueous solution of Cl and 1% HAC (acetic acid), and then washing the alloy powder by using distilled water until the aqueous solution is neutral. Removing the aqueous solution, washing the alloy powder with absolute ethyl alcohol for 2-3 times, and drying the alloy powder in a vacuum drying oven for more than 2 hours. Rare earth-associated oxide (Dy)₂O₃) The dysprosium-iron alloy containing 30-60% dysprosium can be prepared by different dosageAnd (3) pulverizing.

The invention has the beneficial effect that two kinds of environment-friendly fluorides are directly adopted without adopting the environment-friendly fluoridesMetal oxide (Dy)₂O₃，Fe₂O₃) Reduction to Fe with metallic calcium₂Dy intermetallic compounds. The process method has the advantages of low cost, low energy consumption and no environmental pollution, and because two metal atoms directly formed by reducing and diffusing two metal oxides are easy to combine uniformly, the reduction reaction and diffusion reaction time can be greatly shortened, the energy consumption is reduced, the production cost is reduced, the prepared alloy is powdery, the actual use is more convenient, the purity of the alloy is equivalent to that of pure metal dysprosium, and the alloy can be widely applied in related fields instead of the pure metal dysprosium.

Detailed Description

The present invention will be further described with reference to the following examples

Example 1

Dy is reacted with₂O₃200 g, Fe₂O₃172 g of Ca particles 193 (theoretical amount) are mixed uniformly by a mixer and then are mixed by 500kg/cm²Pressing the sample into block material under pressure, placing into a reactor, placing into a resistance heating furnace filled with Ar gas in advance, heating to 980 deg.C, holding for 1 hr, heating to 1150 deg.C, holding for 2 hr, cooling to below 50 deg.C, taking out, soaking in water, stirring, standing, removing turbid liquid, washing with water, repeating until there is no white suspended matter in water, adding 2% NH₄And (2) washing the alloy powder with Cl + 1% HAC (acetic acid) aqueous solution for 3 times, then washing the alloy powder with distilled water until the aqueous solution is neutral, finally washing the alloy powder with absolute ethyl alcohol for 2 times, and then placing the alloy powder into a vacuum drying oven to be dried for 1 hour to obtain 276.8 g of alloy powder, wherein the alloy contains 56.1% of Dy, 43.4% of Fe, 0.10% of Ca and 0.15% of O.

Example 2

Dy is reacted with₂O₃200 g, Fe₂O₃172 g of Ca particles 289.5 g (1.5 times the theoretical amount) treated by the method of example 1, and290.8 g of alloy powder is obtained, the alloy contains 58.5 percent of Dy, 41.1 percent of Fe, 0.15 percent of Ca and 0.13 percent of O.

Example 3

Dy is reacted with₂O₃200 g, Fe₂O₃172 g of Ca particles (386 g: 2 times the theoretical amount) were treated by the method of example 1 to obtain 287.3 g of alloy powder, wherein the alloy contained 58.1% Dy, 41.6% Fe, 0.16% Ca and 0.15% O.

Example 4

Dy is reacted with₂O₃280 g, Fe₂O₃239.6 g of Ca particles 405 g (theoretical amount: 1.5), placing the sample block prepared by the method of example 1 into a vacuum resistance furnace, heating to 900 ℃ of reduction reaction temperature, holding the temperature for 2 hours, heating to 1100 ℃ of diffusion reaction temperature, holding the temperature for 3 hours, treating the reaction-finished material by the method of example 1 to obtain 391.8 g of alloy powder containing 57.0% Dy and 42.6% Fe,0.15% of Ca and 0.12% of O.

Example 5

Dy is reacted with₂O₃560 g, Fe₂O₃479.2 g of Ca particles 810 g (theoretical amount 1.5 times), the sample block prepared by the method of example 1 was put into a vacuum resistance furnace, heated to 1000 ℃ for reduction reaction, held at 1.5 hours, heated to 1150 ℃ for diffusion reaction, held at 2.4 hours, and the reaction-completed material was processed by the method of example 1 to obtain 808 g of alloy powder containing 58.4% Dy, 41.3% Fe, 0.10% Ca and 0.12% O.

Example 6

Dy is reacted with₂O₃280 g, Fe₂O₃239.6 g and 405 g (theoretical amount: 1.5 times), the sample block prepared by the method of example 1 was put into a vacuum resistance furnace, heated to 1100 ℃ for reduction reaction, held at 1 hour, heated to 1200 ℃ for diffusion reaction, held at 2 hours, and the reaction-completed material was treated by the method of example 1 to obtain 396.7 g of alloy powder containing 57.5% Dy, 42% Fe, 0.13% Ca, and 0.15% O.

Example 7

Dy is reacted with₂O₃350 g, Fe₂O₃1060 g of Ca particles 1364 g of the sample block prepared by the method of example 1 was put into a vacuum resistance furnace, heated to 1000 ℃ for reduction reaction, held at 1150 ℃ for 1.5 hours, heated to 1150 ℃ for diffusion reaction, held at 2 hours, and the reaction-completed material was treated by the method of example 1 to obtain 1048 g of alloy powder containing 29% Dy, 70.6% Fe, 0.15% of Ca and 0.14% of O. The Dy-Fe alloy is made of Fe₂Dy intermetallic compound and iron (Fe).

Example 8

660 g of alloy powder in example 5 is utilized, 22 kg of neodymium iron boron alloy is smelted in a 25 kg vacuum induction furnace, and the neodymium iron boron magnet is prepared through the working procedures of ingot casting, crushing, profiling, sintering, heat treatment and the like, and the magnetic property measurement result of Beijing Steel research institute is that the magnetic property is as follows: br ═ 12.56 Kgs; hej ═ 17.96 KOe; (BH) max ═ 34.18 MGOe. Slightly higher than the magnetic performance of the standard magnets of the same grade.

Claims

1. Fe existing in the form of intermetallic compound₂The preparation method of Dy alloy powder adopts a metallic calcium reduction diffusion method, and is characterized in that: directly prepared from two metal oxides (Dy)₂O₃，Fe₂O₃) Dysprosium iron (Fe) containing 30-60 wt% dysprosium is prepared by calcium reduction diffusion₂Dy) alloy powder.

The ingredients are calculated according to the following chemical reaction equation:

the dosage of the reducing agent Ca is 1 to 2 times of the theoretical dosage, the reduction reaction temperature is 900 to 1100 ℃, the holding time is 1 to 2 hours, the diffusion reaction temperature is 1100 to 1200 ℃, the holding time is 2 to 3 hours, and after the reaction is finished, the materials after the reaction are cooled to below 50 ℃.

2. RightsThe method for producing an alloy powder according to claim 1, characterized by: after the reaction is finished, the cooled material is placed in water again for soaking, and is washed repeatedly by 2% NH₄Washing with Cl + 1% HAC (acetic acid) water solution for 3 times, washing with distilled water to neutral, washing with anhydrous ethanol for 2-3 times, oven drying in vacuum drying oven for 2 hr, and vacuum packaging.

3. The method for preparing an alloy powder according to claim 1, wherein: rare earth oxide (Dy)₂O₃) The dosage of the dysprosium iron alloy can be less than the theoretical dosage, and the dysprosium iron alloy prepared by the method is made of Fe₂Dy intermetallic compound and iron.