A rare earth permanent magnet material Pr2Fe 14 Method for improving phase stability of C

Abstract

Pr2Fe, a rare-earth permanent magnet material that can reduce the harm of residual carbon 14 A method for improving the phase stability of C relates to the field of permanent magnet materials technology. It consists of a substance with the following stoichiometric ratio: (Pr,RE)₂Fe 14 C; where RE = Sm, Gd; the preparation process includes batching, smelting, rapid melt quenching, and annealing. Rapid melt quenching is performed in a vacuum rapid quenching furnace with a copper roller speed of 20 ≤ V ≤ 40 m / s under a protective atmosphere. Annealing is performed in an annealing furnace at 500–1100°C under a protective atmosphere. In this invention, Sm₂Fe 14 C and Gd2Fe 14 The high stability of the C phase is achieved by replacing Pr₂Fe with Sm and Gd atoms. 14 Some Pr atoms in C extend Pr2Fe 14 In the stable region of the C phase, pure phase (Pr,RE)2Fe was prepared. 14 Type C rare earth permanent magnet material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of rare earth permanent magnet materials, and in particular to a method for improving the phase stability of Pr2Fe 14 C permanent magnet material. BACKGROUND

[0002] In recent years, with the development of electronic terminal products, higher requirements are put forward for the shape and performance of electronic component products dominated by permanent magnet materials. The traditional preparation method is difficult to meet the demand on one hand, and also brings great waste of rare earth resources on the other hand. Therefore, how to efficiently produce small and special-shaped magnets is a technical problem to be solved. In recent years, metal powder injection molding (MIM) and 3D printing technology have developed rapidly, and their process characteristics are suitable for producing special-shaped devices and can greatly save resources. The introduction of MIM and 3D printing technology in the forming process of rare earth permanent magnet materials can greatly improve the preparation efficiency and resource utilization efficiency of magnets. The key process step of MIM and 3D printing rare earth permanent magnet material is to mix the binder with the rare earth permanent magnet powder and form at high temperature. However, the binder with good performance is mostly organic material, and the carbon element contained therein is difficult to completely remove. The residual carbon will bring great harm to the performance of the permanent magnet material. Therefore, the development of a kind of rare earth permanent magnet material which is not sensitive to residual carbon in performance can greatly improve the applicability of MIM and 3D printing technology in the preparation of permanent magnet materials, and greatly improve the manufacturing capacity of complex shape magnets.

[0003] Pr2Fe 14 C permanent magnet material has the same crystal structure as the main phase Nd2Fe 14 B of Nd-Fe-B permanent magnet, and the Pr2Fe 14 C magnetic anisotropy field is larger, and it is easier to realize magnetic hardening. This means that this kind of material can be used to prepare high-coercivity permanent magnets without heavy rare earths. More importantly, this kind of material itself is a carbide, which has natural insensitivity to residual carbon in the MIM and 3D printing process. Therefore, this material is an ideal candidate for MIM and 3D printing rare earth permanent magnet material. However, the stability of Pr2Fe 14 C phase is low, and must be obtained through slow solid phase transformation within a specific temperature range, which is not conducive to large-scale production. In order to overcome this difficulty, it is necessary to design new composition and process to accelerate the solid phase transformation process of Pr2Fe 14 C, so as to efficiently obtain stable single phase. SUMMARY

[0004] The purpose of the present application is to provide a method for rapidly and stably obtaining pure Pr2Fe 14 C phase, and the Pr2Fe14 C material or Pr2Fe 14 C material has high phase stability.

[0005] To achieve the above-mentioned purposes of the application, the application provides the following technical solutions.

[0006] The application provides a scheme for improving the Pr2Fe 14 C phase stability, the composition of Pr2Fe 14 C alloy is adjusted by using medium and heavy rare earth elements to improve the phase stability, and the scheme is characterized by having the following chemical composition:

[0007] (Pr, RE)2Fe 14 C (formula 1) and is a pure phase structure of 2:14:1.

[0008] In the formula 1, RE is a medium and heavy rare earth element such as Sm and Gd.

[0009] The application provides a preparation method of the (Pr, RE)2Fe 14 C phase described in the above scheme, and the method comprises the following steps.

[0010] (1) Melting a mixture including RE, Pr, Fe and C to obtain an ingot, and during batching, Pr and RE are additionally increased by 1-5% to compensate for loss, and preferably, the nominal composition of Pr6RE9Fe 14 C is batched according to the following formula 1; 79 C6.

[0011] (2) Rapidly quenching the ingot in a melt to obtain a rapidly quenched ribbon.

[0012] (3) Annealing and quenching the rapidly quenched ribbon under argon protection to obtain a (Pr, RE)2Fe 14 C type rare earth permanent magnet material.

[0013] In step (1), the mass of Fe and C corresponds to the theoretical mass in formula 1, and the mass of Pr and RE is increased by 1-5% based on the theoretical mass of Pr and RE calculated according to formula 1.

[0014] In step (2), the melting is performed in a high-frequency induction melting furnace.

[0015] In step (2), the melt rapid quenching is performed in a melt rapid quenching furnace, and during the rapid quenching process, the rotating speed of the copper roller is 20-40 m / s, the diameter of the quartz tube nozzle is 0.5-2 mm, and the distance from the bottom of the quartz tube to the copper roller is 2-4 mm.

[0016] In step (3), the annealing temperature is 500-1100 ℃, and the time is 0.01-1 h.

[0017] The annealing in step (3) is carried out in a semi-open environment filled with protective gas.

[0018] Preferably, the annealing in step (3) comprises: placing a quartz tube with one end closed and one end open in a heating furnace, passing in argon at a speed of 10 L / min, and heating the furnace to a temperature of 500-1100 ℃; after 10-30 min, placing the quenched ribbon obtained in step (2) in a crucible or a tantalum foil, preheating the mouth of the quartz tube, and after 5-10 min, pushing the sample into the bottom end of the quartz tube for annealing. The annealing time is 0.01-1 h.

[0019] Preferably, the quenching in step (3) is carried out by ice water quenching.

[0020] The application provides a (Pr, RE)2Fe 14 The C-type rare earth permanent magnet material is formed by a substance with a chemical composition shown in formula 1: (Pr, RE)2Fe 14 C (formula 1); in formula 1, RE is a medium or heavy rare earth element such as Sm and Gd. The application uses the high stability of the RE2Fe 14 C phase formed by Sm and Gd and the like to replace Pr elements, thereby improving the phase stability of (Pr, RE)2Fe 14 C.

[0021] The application provides a (Pr, RE)2Fe 14 The application provides a preparation method of a C-type rare earth permanent magnet material, which comprises the following steps: smelting a mixture containing RE, Pr, Fe and C to obtain an ingot; carrying out melt quenching on the ingot to obtain a quenched ribbon; annealing and quenching the quenched ribbon under argon protection to obtain a (Pr, RE)2Fe 14 C-type rare earth permanent magnet material; the mass of Fe and C corresponds to the theoretical mass in formula 1, and the mass of Pr and RE is increased by 1-5% based on the theoretical mass of Pr and RE calculated according to formula 1. The application uses the high stability of the RE2Fe 14 C phase formed by Sm and Gd and the like to replace Pr elements, thereby improving the phase stability of (Pr, RE)2Fe 14 C; after annealing, a (Pr, RE)2Fe 14 C pure phase is obtained; then quenching is carried out to ensure that the (Pr, RE)2Fe 14 C pure phase does not decompose in the cooling process.

[0022] The main advantages of the present application relative to other prior art are: mixed use of rare earth elements is conducive to balanced use of rare earth resources; middle and heavy rare earth substitution is conducive to improving Curie temperature of Pr2Fe 14 C; middle and heavy rare earth substitution is conducive to expanding stable interval of Pr2Fe 14 C phase; middle and heavy rare earth substitution is conducive to improving temperature stability of Pr2Fe 14 C permanent magnet material. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD pattern of the sample of Example 1;

[0024] Figure 2 XRD pattern of the sample of Example 2;

[0025] Figure 3 XRD pattern of the sample of Comparative Example 1.

[0026] The upper left corner of the figure is the nominal composition, and the corresponding upper right corner is the corresponding pure phase structure. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with specific embodiments, but the present application is not limited to the following embodiments.

[0028] Example 1

[0029] (1) The pure Sm, Pr, Fe elements with a purity of 99.9% and the Fe-C alloy raw material with a mass fraction of 5% were mixed according to the stoichiometric ratio Pr6Sm9Fe 79 C6.

[0030] (2) The prepared raw material was placed in a vacuum arc melting furnace and melted under an argon atmosphere to obtain an alloy ingot. The melting was repeated 4 times, and after the sample was completely cooled, it was taken out of the furnace for use.

[0031] (3) The melted ingot was crushed and loaded into a quartz tube with a nozzle diameter of 0.5-2mm at the bottom; the quartz tube was loaded into a melt rapid quenching furnace, and the bottom of the quartz tube was 2-4mm away from the copper roller; when the ingot was remelted in the quartz tube, the copper roller was opened and adjusted to a rotation speed of 40m / s, and the liquid obtained by remelting was vertically sprayed onto the copper roller to obtain a rapid quenching ribbon.

[0032] (4) The quenched ribbon is annealed and quenched under argon protection. The annealing step is as follows: a quartz tube with one end closed and a gas tube are put into a muffle furnace and argon is blown for 10 minutes. The quenched ribbon is wrapped with a specially-made tantalum sheet, put into the quartz tube for preheating for 10 minutes, and then the sample wrapped with the tantalum sheet is pushed into the bottom end of the quartz tube for isothermal annealing at 850°C for 1 hour. Subsequently, the sample is quenched in ice water. The annealing and quenching processes are always carried out in an argon-blowing environment.

[0033] Example 2

[0034] (1) The pure Gd, Pr and Fe elements with a purity of 99.9% and the Fe-C alloy raw material with a mass fraction of 5% are mixed according to the stoichiometric ratio Pr6Gd9Fe 79 C6.

[0035] (2) The prepared raw materials are put into a vacuum arc melting furnace and melted under an argon atmosphere to obtain alloy ingots. The melting is repeated for 4 times, and the sample is taken out from the furnace after completely cooling.

[0036] (3) The melted ingot is crushed and put into a quartz tube with a nozzle diameter of 0.5-2 mm at the bottom end. The quartz tube is put into a melt quenching furnace, and the bottom end of the quartz tube is 2-4 mm away from the copper roller. When the ingot is remelted in the quartz tube, the copper roller is opened and adjusted to a rotating speed of 40 m / s, and the liquid obtained by remelting is vertically sprayed onto the copper roller to obtain a quenched ribbon.

[0037] (4) The quenched ribbon is annealed and quenched under argon protection. The annealing step is as follows: a quartz tube with one end closed and a gas tube are put into a muffle furnace and argon is blown for 10 minutes. The quenched ribbon is wrapped with a specially-made tantalum sheet, put into the quartz tube for preheating for 10 minutes, and then the sample wrapped with the tantalum sheet is pushed into the bottom end of the quartz tube for isothermal annealing at 850°C for 1 hour. Subsequently, the sample is quenched in ice water. The annealing and quenching processes are always carried out in an argon-blowing environment.

[0038] Comparative Example 1

[0039] (1) The pure Pr and Fe elements with a purity of 99.9% and the Fe-C alloy raw material with a mass fraction of 5% are mixed according to the stoichiometric ratio Pr 15 Fe 79 C6.

[0040] (2) The prepared raw materials are put into a vacuum arc melting furnace and melted under an argon atmosphere to obtain alloy ingots. The melting is repeated for 4 times, and the sample is taken out from the furnace after completely cooling.

[0041] (3) The smelted ingot is broken and loaded into a quartz tube with a bottom nozzle diameter of 0.5-2 mm; the quartz tube is loaded into a melt rapid quenching furnace, and the bottom of the quartz tube is 2-4 mm away from the copper roller; when the ingot is remelted in the quartz tube, the copper roller is opened and the rotating speed is adjusted to 40 m / s, the liquid obtained by remelting is vertically sprayed onto the copper roller, and a rapid quenching ribbon is obtained.

[0042] (4) The rapid quenching ribbon is annealed and quenched under argon protection. The annealing step is as follows: the quartz tube with one end closed and one end open and the gas pipe are placed into a muffle furnace, and argon blowing is opened for 10 min. The rapid quenching ribbon is wrapped with a special tantalum sheet, and is placed at the quartz tube opening and preheated for 10 min, and then the sample wrapped with the tantalum sheet is pushed into the bottom end of the quartz tube for 600-850℃, 1h isothermal annealing. Subsequently, quenching in ice water. The annealing and quenching process is always carried out in an argon blowing environment.

[0043] Figure 1 It is shown that a pure (Pr, Sm)2Fe 14 C phase is obtained in Example 1, and no other impurity phase is present, which shows that the preparation method of the application can obtain a pure phase (Pr, Sm)2Fe 14 C type rare earth permanent magnet material. In contrast, in Comparative Example 1, since no Sm element is added, it cannot obtain (Pr, Sm)2Fe 14 C phase.

[0044] Figure 2 It is shown that a pure (Pr, Sm)2Fe 14 C phase is obtained in Example 2, and no other impurity phase is present, which shows that the preparation method of the application can obtain a pure phase (Pr, Sm)2Fe 14 C type rare earth permanent magnet material. In contrast, in Comparative Example 1, since no Sm element is added, it cannot obtain (Pr, Sm)2Fe 14 C phase.

[0045] Figure 3 It is shown that in Comparative Example 1, since no Sm and Gd elements are added, it cannot obtain (Pr, RE)2Fe 14 C phase.

[0046] Although specific embodiments of the application have been described, it will be apparent to those skilled in the art that other various changes and modifications can be made without departing from the spirit and scope of the application. Therefore, the appended claims are intended to cover all such changes and modifications that fall within the scope of the application.

Claims

1. A rare earth permanent magnet material Pr2Fe that can improve and reduce the harm of residual carbon. 14 The method for C-phase stability is characterized by... Pr2Fe was replaced with medium and heavy rare earth elements. 14 By partially removing Pr atoms from C, a substance with the following stoichiometric ratio is prepared: (Pr,RE)₂Fe 14 C, where RE = Sm, Gd; and is a pure phase structure of 2:14:1; Includes the following steps: The mixture containing RE, Pr, Fe and C is smelted to obtain an ingot; The ingot is subjected to rapid melt quenching to obtain a rapid quenching band; The rapidly quenched strip was annealed and quenched under argon protection to obtain (Pr,RE)2Fe. 14 Type C rare earth permanent magnet materials; The mass of Fe and C corresponds to (Pr,RE)2Fe 14 The theoretical mass in C, the mass of Pr and RE according to the formula (Pr,RE)2Fe 14 The theoretical Pr and RE quality calculated by C are increased by 5% respectively; The rapid quenching of the melt is carried out in a rapid quenching furnace. During the rapid quenching process, the copper roller rotates at a speed of 20-40 m / s, the diameter of the quartz tube nozzle is 0.5-2 mm, and the bottom of the quartz tube is 2-4 mm away from the copper roller. Annealing: Place a quartz tube with one end closed and the other open in a heating furnace, and introduce argon gas at a rate of 10 L / min. The furnace temperature is 500-1100℃. After 10-30 min, place the quenched strip in a crucible or tantalum foil, place it at the mouth of the quartz tube for preheating for 10 min, and then push the sample into the bottom of the quartz tube for annealing. The annealing time is 0.01-1 h.

2. The method according to claim 1, characterized in that, The melting is carried out in a high-frequency induction melting furnace.

3. The method according to claim 1, characterized in that, The annealing is carried out in a semi-open environment filled with protective gas.

4. The method according to claim 1, characterized in that, The quenching method is ice water quenching.

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