JPH0711301A - Production of permanent magnet powder material - Google Patents

Abstract

PURPOSE:To form the alloy powder of a ferromagnetic phase by executing mechanical ironing to induce a solid phase reaction in place of the process for production of MnAlC magnet powder by the conventional casting-solution treatment-hot extrusion process or gas atomizing-hot extrusion process requiring a melting stage which requires a large quantity of heat energy or a casting stage which generates segregation. CONSTITUTION:The ferromagnetic powder consisting of the MnAlC alloy is produced by realizing alloying by the mechanical ironing to induce the solid reaction by executing the milling using various kinds of ball mills, such as planetary gear ball mills, rolling mills or attrition mills, with a powder mixture composed of constituting unit elements of the MnAlC alloy consisting of pure Al, pure Mn, pure carbon, pure Ni, etc. The ferromagnetic powder is further executed to a heat treatment after the mechanical ironing described above in order to enhance the content of the ferromagnetic phase, by which the diffusion of the elements is activated and the formation of the quasi-stable ferromagnetic tau phase is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a permanent magnet powder material used for producing an MnAlC alloy magnet.

[0002]

2. Description of the Related Art In MnAlC alloys, it is the metastable phase that exhibits ferromagnetism. In order to produce this ferromagnetic phase, it is usually controlled by cooling during melting after solidification or by isothermal annealing after cooling. Either method is performed.

As an industrial manufacturing method of this magnet as a permanent magnet, a process of casting-solution-warm extrusion after melting the mother alloy at a high temperature of 1500 ° C. or more is used in recent years, and recently, As a powder process, a process of gas atomizing powder of mother alloy-warm extrusion is mainly used to produce a rapidly cooled powder after melting at 1500 ° C. as in the above process. However, in any of these processes, a melting step that requires a large amount of heat energy is inevitable. Further, in the former case, there is a point that industrial improvement is necessary in principle in which segregation of constituent components cannot be avoided in the casting process after melting.

[0004]

As described above, according to the conventional casting-solution-warm extrusion process or gas atomization-warm extrusion process that requires a melting process requiring a large amount of heat energy or a casting process that causes segregation. Instead of the manufacturing method of the MnAlC-based magnet powder, the alloy powder of the ferromagnetic phase is to be generated by the solid-phase reaction without such a problem.

[0005]

[Means for Solving the Problems] A mixed powder obtained by mixing elemental constituent elements of an MnAlC-based alloy composed of pure Al metal, pure Mn metal, pure carbon, etc. to the magnet alloy composition ratio is used as a starting material, and a planetary ball mill and rolling mill are used. Milling is performed by using various ball mills such as a mill or an attrition mill, and mechanical alloying that causes a solid-phase reaction is performed to realize alloying, thereby producing a ferromagnetic powder in an MnAlC alloy. Further, in order to further increase the content rate of the ferromagnetic phase, heat treatment is further performed after the mechanical alloying to activate diffusion of the element and generate a metastable ferromagnetic phase.

[0006]

In the method for producing a permanent magnet material of the present invention,
Segregation during solidification, that is, primary crystal and residual liquid coagulation part, because mechanical alloying using a ball mill, that is, solid-phase reaction, produces the target powder containing ferromagnetism In principle, the compositional difference of the main components cannot be caused, and the permanent magnet manufactured by the method of the present invention has a single composition. Also, the present invention does not require a large amount of heat energy because it has no melting step.

[0007]

EXAMPLES Table 1 summarizes various implementation conditions such as the composition ratio of the constituent elemental elements of the permanent alloy magnet material powder, mechanical alloying conditions and heat treatment conditions in Examples 1 to 5 described below of the present invention. Show.

[0008]

[Table 1]

Embodiment 1. The powders of pure Mn, pure Ni, pure Al and pure carbon shown in FIG. 1 were Mn: 68 wt%, C:
0.4 wt%, Ni: 0.8 wt%, Al: bal. The total amount of 50 g was weighed so that the ratio became, and set in a planetary ball mill, and milled at 200 rpm for up to 50 hours. All the balls and pots used were made of agate, 100 balls were 10 mm in diameter, and the pot capacity was 250.
It was cc. During the milling, the ball mill was appropriately stopped and the sample powder was sampled to measure changes in the external shape and magnetic characteristics with temperature. The external shape is shown in FIG. Fig. 3 shows the change in magnetic properties depending on the alloying time. Figure 3
It can be seen from the results that the Curie point does not change depending on the alloying time, and the generated ferromagnetic τ phase is the same. Example 1 above
FIG. 4 shows the X-ray diffraction result of the powder obtained by further heat-treating the powder mechanically alloyed with. In FIG. 4, together with α-Mn that is a starting material, β-Mn of a stable phase that is a generated material, and carbide (Mn ₃ AlC) that is a precipitated phase, the τ phase of a metastable phase that is ferromagnetic is X-ray-like. Confirmed.

Embodiment 2. Powders of pure Mn, pure Ni, pure Al and pure carbon are Mn: 70 wt% and C: 0.4 wt.
%, Ni: 0.8 wt%, Al: bal. The total amount of 75 g was weighed so that the ratio became, and set on a planetary ball mill, and milled at 250 rpm for 10 hours. All the balls and pots used were made of agate, 100 balls were 10 mm in diameter, and the pot capacity was 250 cc. After milling, take out the powder from the container and 1000 in Ar gas atmosphere.
After heat treatment at ℃ 10 minutes, water-cooled, further heated to 650 ℃ 3
Heat treatment was performed for 0 minutes. The magnetic properties and thermomagnetic properties are shown in FIGS. 5 and 6.

The ball-milled powder is A by X-ray diffraction.
Only the diffraction peaks of 1 and Mn were observed, and the ε phase and τ phase diffraction peaks were not observed. However, as you can see in Figure 6,
After the ball milling, a heat treatment at 1030 ° C. for 30 minutes was performed, and an ε phase was formed. Further, a heat treatment at 650 ° C. generated a ferromagnetic τ phase. As shown in Fig. 5, the generated τ
The Curie point of the phase was 315 ° C.

Embodiment 3. Pure Mn, pure Ni, pure Al, and pure carbon powders were Mn: 73 wt% and C: 0.4 wt.
%, Ni: 1.0 wt%, Al: bal. The total amount of 100 g was weighed so that the ratio became, and set in a planetary ball mill and milled at 250 rpm for 10 hours. The balls and pots used are made of agate, and the balls are 10 mm.
The diameter of 100 pieces and the capacity of the pot were 250 cc. After milling, take out the powder from the container and put it in an Ar gas atmosphere at 100
After heat treatment at 0 ° C for 10 minutes, cool with water, and further raise the temperature to 650 ° C.
Heat treatment was performed for 30 minutes to obtain a ferromagnetic phase.

Embodiment 4. Powders of pure Mn, pure Ni, pure Al and pure carbon were Mn: 66 wt% and C: 0.4 wt.
%, Ni: 0.6 wt%, Al: bal. The total amount of 50 g was weighed so as to be the above ratio, set in a planetary ball mill, and milled at 200 rpm for 15 hours. All the balls and pots used were made of agate, 100 balls were 10 mm in diameter, and the pot capacity was 250 cc. The powder taken out after milling had a ferromagnetic phase.

Example 5. Powders of pure Mn, pure Ni, pure Al and pure carbon are Mn: 70 wt% and C: 0.4 wt.
%, Ni: 0.8 wt%, Al: bal. The total amount of 30 g was weighed so that the ratio became, and set in a planetary ball mill, and milled at 150 rpm for 10 hours. Both the balls and pots used were made of agate, the diameter of the 10 balls was 50, and the pot capacity was 250 cc. The powder taken out after milling had a ferromagnetic phase.

[0015]

As described above, according to the manufacturing method of the present invention, the ferromagnetic phase in the MnAlC alloy magnet can be generated without taking a hot step such as melting and casting, and the constituent components are dispersed in the inside and outside of the powder. It is possible to produce a uniform powder for permanent magnets. Moreover, large-scale production is easy and the industrial value is great.

[Brief description of drawings]

FIG. 1 is a micrograph showing the appearance of raw material powder in the present invention.

FIG. 2 is a photomicrograph showing the appearance of permanent magnet powder produced according to the present invention.

FIG. 3 is a thermomagnetic curve of a permanent magnet powder manufactured according to the present invention.

FIG. 4 is an X-ray diffraction pattern of a ferromagnetic phase of a permanent magnet powder manufactured according to the present invention.

FIG. 5 is a thermomagnetic curve of a permanent magnet powder produced by performing heat treatment after mechanical alloying in the present invention.

FIG. 6 is an X-ray diffraction pattern of a ferromagnetic phase produced by performing heat treatment after mechanical alloying in the present invention.

[Explanation of symbols]

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[Procedure amendment]

[Submission date] January 14, 1994

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a micrograph of a particle structure of a raw material powder according to the present invention.

FIG. 2 is a micrograph of a particle structure of a permanent magnet powder manufactured according to the present invention.

FIG. 3 is a diagram showing a graph of a thermomagnetic curve of a permanent magnet powder manufactured according to the present invention.

FIG. 4 is a view showing a graph of an X-ray diffraction pattern of a ferromagnetic phase of a permanent magnet powder manufactured according to the present invention.

FIG. 5 is a graph showing a thermomagnetic curve of a permanent magnet powder produced by performing heat treatment after mechanical alloying in the present invention.

FIG. 6 is a diagram showing a graph of an X-ray diffraction pattern of a ferromagnetic phase produced by performing heat treatment after mechanical alloying in the present invention.

Claims (3)

[Claims] 1. In the manufacture of a MnAlC-based alloy permanent magnet powder material, after mixing each constituent element powder of the alloy to the magnet alloy composition ratio, a mechanical ironing for causing a solid phase reaction is performed to obtain a ferromagnetic magnet. A method for producing a permanent magnet powder material, which comprises producing a powder. 2. In the manufacture of a MnAlC-based alloy magnet powder material, after mixing each constituent element powder of the alloy to the magnet alloy composition ratio, mechanical ironing for causing a solid phase reaction is performed, and the alloy powder is further added. A method for producing a permanent magnet powder material, which comprises heat-treating to produce a ferromagnetic magnet powder. 3. The mechanical ironing for causing a solid-phase reaction is a milling action by various ball mills such as a planetary ball mill, a rolling mill or an attrition mill, and the like. Manufacturing method of permanent magnet powder material.