Process for producing rare earth permanent magnet material
A technology of permanent magnets and magnets, applied in the direction of magnetic materials, magnetic objects, inorganic materials, etc., can solve the problems of difficulty in preparing magnetic and heat-resistant R-Fe-B ultrafine magnet bodies, inapplicability, etc., and achieve excellent magnetic properties. and heat resistance, magnetic recovery effect
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[0037] Master alloys are prepared by melting metal or alloy raw materials in a vacuum or an inert gas atmosphere, preferably in an argon atmosphere, and casting the melt into flat or hinged molds or strip casting. A possible alternative is the so-called dual-alloy process, which involves the separate preparation of R 2 Fe 14 Alloys composed of B compounds and R-rich alloys acting as liquid phase aids at sintering temperatures were crushed, weighed and mixed. It is worth noting that, if necessary, the alloy with a composition close to the main phase should be homogenized in order to increase the R 2 Fe 14 The amount of the B compound phase because α-Fe may remain depending on the cooling rate during casting and the composition of the alloy. The homogenization treatment is a heat treatment at a temperature of 700-1200° C. for at least 1 hour in vacuum or in an argon atmosphere. The so-called melt quenching technique and the aforementioned casting technique can be applied to ...
Embodiment 1 and comparative example 1
[0074] A thin plate-shaped alloy is prepared by using neodymium, iron, cobalt, and aluminum metals and iron-boron with a purity of at least 99% by weight, weighing a predetermined amount of the above-mentioned substances, high-frequency melting them in an argon atmosphere, and then pouring the melt onto copper single chill rolls (strip casting technology). The alloy consists of 12.5 atomic % neodymium, 1.0 atomic % cobalt, 1.0 atomic % aluminum, 5.9 atomic % boron and the balance iron. Name it Alloy A. Alloy A was machined into a coarse powder of less than 30 mesh by the so-called hydrogenation comminution technique, which involves hydrogenating the alloy and heating to 500° C. while evacuating the chamber to partially decompose the hydrogenation.
[0075] Separately, the alloy is prepared as follows: using neodymium, dysprosium, iron, cobalt, aluminum and copper metals and iron boron with a purity of at least 99% by weight, weighing a predetermined amount of the above substa...
Embodiment 2 and comparative example 2
[0083] Using the same composition and procedure as in Example 1, a 10 mm x 20 mm x 15 mm thick sintered block was prepared. The sintered block is machined to a specific surface area S / V of 24mm using an inner blade cutting machine -1 A cuboid of predetermined size. The as-machined sintered body was washed sequentially with alkaline solution, deionized water, acid and deionized water, and then dried.
[0084] Then, dysprosium oxide with an average particle size of 1 μm, dysprosium fluoride with an average particle size of 5 μm, and ethanol were mixed in weight fractions of 25%, 25% and 50%, and the magnet body was immersed therein for 1 minute and ultrasonic waves were applied. The magnet body is removed and immediately dried with hot air. At this time, dysprosium oxide and dysprosium fluoride occupy a space at an average distance of 16 micrometers from the surface of the magnet, and the filling factor is 50% by volume.
[0085] according to figure 1 The procedure shown, HD...
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