JPS62164849A - Rare earth ferrous permanent magnet - Google Patents

Abstract

PURPOSE:To develop a small-sized magnet having high performance and high quality by adding a specific ratio of Al to a ternary magnet alloy consisting of rare earth-iron-boron. CONSTITUTION:Powder, sized 3-5mum diameter, of the alloy composed of the compsn. consisting of 8-20% R (at least >=1 kinds of rare earth elements contg. Y), 3-12% B, 0.01-4.0% Al, and the balance Fe is formed and the molding thereof is formed by exerting pressure thereto in the magnetic field direction and perpendicular direction in a magnetic field of 10,000 oersted in the stage of producing the small-sized high-performance magnet to be used for small-sized speakers, peripheral terminals of computers, step motors of analog electronic timepieces, etc. Such molding is sintered for 1-2hr at 1,050-1,150 deg.C in a vacuum and further, the gaseous atmosphere is replaced with Ar at the same time, then the molding is subjected to additional sintering for 2hr and is cooled down to a room temp. at a cooling rate of 50 deg.C/hr. The squareness characteristic at the Curie point and in the demagnetization curve is improved, by which the stable permanent magnet having the decreased fluctuation of magnetic force by an environmental temp. change and shape change is obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to the improvement of a rare earth-iron-boron ternary magnet alloy, which can be used as one of the materials related to various industrial and consumer electronic/electric appliances. used in

Specifically, it is used in a wide range of fields, including small speakers, computer peripheral terminals, and various motors such as step motors for analog electronic watches.

The present invention focuses on the use of small magnets, which require higher performance and higher quality.

(Prior Art) Japanese Unexamined Patent Publication No. 59-46008 discloses a method for manufacturing a ternary rare earth iron boron alloy magnet.

(Problems to be Solved by the Invention) Conventional rare earth iron boron ternary alloy permanent magnet materials contain a large amount of iron (more than 60 wt%) to improve performance. The temperature dependence of the residual magnetic flux is low at around 350° C., and the demagnetization curve of the conventional samarium cobalt permanent magnet is poor.

In order to improve these drawbacks, the present invention improves the squareness of the single point and demagnetization curve without significantly impairing the magnetic properties, and reduces fluctuations in magnetic force due to environmental temperature changes and permeance changes (shape changes). The purpose is to provide stable permanent magnets.

(Means for Solving the Problems) In order to solve the above problems, the present invention proposes that a method using additive elements is effective for improving the Curie point and magnetic properties in rare-transition metal alloys. Considering that this is one of the most effective methods, we prepared a number of composition systems based on the rare iron boron system and attempted experimental studies.

As a result, this invention is based on the discovery that the composition shown in the above-mentioned claims contributes to improving the Curie point and squareness in the demagnetization curve. Furthermore, M4
．． Since addition of 0% or more causes a significant decrease in residual magnetic flux density, it is limited to 4.0% or less.

(Example) Praseodymium 5-6 at%, neodymium 9-1 Qat%,
Boron 6-8 at%, Aluminum 1-2 at%, balance [
A button-shaped ingot 1- is produced in an arc melting furnace by weighing so as to have the composition of e. After this, 1M with Show Crusher
Crushed to R angle, 50-100I with a disc mill
Coarse pulverization is carried out up to IIR, and finally powder with a particle size of 3 to 5JJ11 is obtained using a vibrating ball mill. Next, in order to impart orientation to the magnetic powder, a pressure of 2 tons/= is applied in a direction perpendicular to the direction of the magnetic field in a magnetic field of 10,000 oersteds to form a molded body. Next, in order to achieve high density, sintering was performed at 1050 to 1150°C for 1 to 2 hours in a vacuum of about 10'Torr, and then the atmosphere was replaced with Ar gas at the same temperature and sintered for an additional 2 hours. It was cooled to room temperature at a gradient of about 50°C per hour.

Sample measurement is performed by cutting out a block and horizontal coaxial compensation 4πI
The magnetic properties were determined from the demagnetization curve obtained by measurement using a coil. Also, one Curie is VSM (Vibrat)
ing Sample Magnetometer).

The results are shown below for the praseodymium-neodymium mixed crystal system.

However, the squareness ratio is defined in the text using the following formula.

It can be seen that compared to the conventional ternary system, the Curie point improved by a maximum of 40 degrees Celsius, and the squareness ratio improved by a maximum of about 3%.

(Effects of the Invention) As explained above, the present invention achieves the Curie point and demagnetization curve by adding M as the fourth element to the R-Fe-83 element alloy or by using it as a quaternary alloy. By improving the squareness ratio, a stable magnet with small residual magnetic flux fluctuations due to environmental temperature changes and permeance changes has been achieved. Its industrial significance is not small.

Claims (1)

[Claims] 8 to 20% R (R is at least one kind of rare earth element including Y), 3 to 12% B (boron) in atomic percentage
, 0.01-4.0% Al (aluminum), balance F
A permanent magnet alloy characterized by being an alloy having a composition consisting of e (iron).