JPH05247601A - Alloy for corrosion resistant permanent magnet and method for producing permanent magnet therefrom - Google Patents

Abstract

PURPOSE: To obtain a permanent magnet having high magnetic properties and corrosion resistance by magnetically arraying alloyed particles essentially consisting of Na-Fe-B, compacting them, executing heating and cooling at specified temps. and thereafter aging the same.

CONSTITUTION: An alloy for a permanent magnet consisting essentially of Nd- Fe-B and having a compsn. in which the main part has Nd₂Fe₁₄B type permanent magnet phases, and, containing, by weight, 2.5 to 20% Co, 0.1 to 1.2% Al and 0.5 to 3% Zr is formed. The particles obtd. by pulverizing the alloy having this compsn. are magnetically arrayed and compacted, which is furthermore sintered to form a perfectly dense magnet object. This magnet object is heated at 850 to 950°C for about 30 to 120 min and is cooled to about 440 to 550°C at a cooling rate of about 5 to 50°C/min. After that, it is subjected to aging treatment in the range of about 500 to 750°C. In this way, the permanent magnet in which intrinsic coercive force is maintained or improved and inherently resists to corrosion can be produced.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy for permanent magnets and a method for producing permanent magnets therefrom, which gives an improved combination of corrosion resistance and intrinsic coercivity without compromising remanence and energy products. It is a thing.

[0002]

2. Description of the Prior Art Permanent magnets of one or more rare earth elements, iron and boron, in particular neodymium, iron and boron permanent magnets with most of the famous Nd ₂ Fe ₁₄ B magnetic phase, are notable magnetically. It is known to exhibit properties. However, magnets of these compositions are susceptible to corrosion, especially in hot, humid applications. Poor corrosion resistance is attributed to the rare earth-rich phase, which is particularly susceptible to oxidation in humid environments. During use, the corrosion of these magnets results in deterioration of their magnetic properties, producing contaminants that may be harmful to the magnetic circuit in which they are used. Various coating techniques and surface treatments have been proposed to improve the corrosion resistance of these magnets. Although these treatments are somewhat successful, the high oxidative properties of these magnet alloys result in deleterious corrosion in the presence of slight defects or discontinuities in any protective surface coating.

[0003]

Therefore, the first object of the present invention is to obtain a remanence (Br) and an energy product (BH _max ).
To provide an alloy for permanent magnets that retains or improves the intrinsic coercivity (H _ci ) without sacrificing heat resistance and inherently resists corrosion. Another object of the invention is to provide a method for producing permanent magnets from the alloys of the invention, which will result in the desired permanent magnet properties described below without the need for complicated heat treatment processes.

[0004]

SUMMARY OF THE INVENTION Generally, the invention provides:
The permanent magnet alloy contains a typical Nd-Fe-B composition having a predominantly Nd ₂ Fe ₁₄ B type magnetic phase. According to the invention, this general composition is modified by the addition of cobalt, aluminum, zirconium, combinations thereof to the alloy.
By weight, cobalt is present in the range 2.5 to 20%, preferably 2.5 to 15% and aluminum is 0.1 to 1.2.
% Range, preferably 0.2 to 1.2%, more preferably
0.2 to 0.6% present, zirconium 0.5 to 3.0%
Is present, preferably 0.5 to 2%. Dysprosium will exist as an additional rare earth element replacing some of the neodymium. The amount of Dy that does not exceed 5% is (Nd-D
y) It will be present in most permanent magnet phases that are ₂ Fe ₁₄ B. Oxygen is 1.0% or less, preferably 0.8% or less,
Should be suppressed as a residual element.

By the method of the invention, the alloy for permanent magnets according to the above will be produced as prealloyed particles. The pre-alloyed particles will be produced by existing methods, either inert gas atomization or milling of the casting. The particles are magnetically aligned, consolidated, such as cold equilibrium compression, and sintered at temperatures in the range of 950 ° C. to 1100 ° C., resulting in a completely dense magnetic body. The sintered magnet body is heated at a temperature of 850 ° to 950 ° C. for 30 to 120 minutes and 400 to 5 at a cooling rate of 5-50 ° C./min.
It is cooled to 50 ° C. and then aged at a temperature in the range 500 to 750 ° C., preferably at a temperature of 550 ° to 700 ° C. Prior to compacting the particles, the particles should be mixed with a carbon-containing lubricant such as a metal fatty acid compound such as zinc stearate or a lubricant of a hydrocarbon compound and milled to reduce its size. Let's do it. Zinc stearic acid will be mixed in an amount of about 0.1%.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sample materials and magnets used in the experiments, and the specific examples of the invention described below, were prepared by powder metallurgy from induction melting permanent magnet alloys. The alloy contained at least neodymium or a combination of neodymium with minor amounts of other rare earth elements along with iron, cobalt, zirconium, aluminum and boron. Other transition elements such as vanadium or niobium have also been added in some alloys instead of zirconium. The alloy was produced by vacuum induction melting of a pre-alloyed charge to produce a molten mass of the desired alloy composition. The melt mass was poured into molds or atomized into fines using an argon gas jet for atomization. Casting ingot or atomized powder is 1 to 30
Hydrogenated at atmospheric pressure. The cast ingot was crushed and crushed to coarse particles. The coarse particles or atomized powder was then milled to reduce size by jet milling with argon or nitrogen gas. The milled powder portion and the atomized powder were mixed with zinc stearate to improve the jet mill micronization operation.
Additional powder samples were jet milled without mixing with zinc stearate. The average particle size of the jet milled powders was determined by the Fisher sub-sieves.
ve) Size measurement ranged from 1 to 4 microns.

The pre-alloyed powder prepared as described above was placed in a rubber bag, aligned in a magnetic field and molded by cold equilibrium compression. Then the cold compression molded product is
Completely sintered to theoretical density in a vacuum furnace at 950 ° C to 1100 ° C for 2 hours. The obtained sintered magnet was further heat-treated at about 900 ° C. for 1 hour, gradually cooled to 500 ° C. at 20 ° C./minute, and then rapidly cooled by blowing gas.
The magnet was then aged at a temperature within the range of 550 ° C to 700 ° C. The aged magnet was broken into a cylindrical shape.

The magnetic properties of the magnet were measured by a hysteresigraph. The resulting accelerated corrosion test, reported below, was carried out in an autoclave at a temperature of 110 ° C to 115 ° C and a vapor pressure of 0.35 to 0.7 kg / cm ² (5 to 10 psi). These tests are for rare earth,
It is art-accepted to provide accurate and reliable data on the long-term corrosion behavior of iron and boron magnets. After this autoclave test, the weight loss of the samples was measured by a balance after removing the corrosion products from the samples, and the frequency of the corrosion degree of each sample was obtained. As shown in Table 1, four alloy compositions for permanent magnets were produced, and magnets were produced from each of these compositions by the method described above.

[0009]

[Table 1]

Temperature of 110 ° C to 115 ° C, 0.35 to 0.7
The corrosion rate was evaluated by measuring the weight loss of the magnet 96 hours after the autoclave test with a vapor pressure of kg / cm ² (5-10 psi).

[0011]

[Table 2]

As shown in Table 2, sample magnets containing zirconium, vanadium, or niobium with cobalt and aluminum show substantially reduced weight loss. In these samples, only cobalt, aluminum and zirconium containing magnets showed near zero weight loss. Two other magnets containing vanadium or niobium and cobalt and aluminum showed small weight loss,
Nevertheless, corrosion was observed on the surface.

The intrinsic coercivity was substantially increased by the combined addition of vanadium, columbium or zirconium with dysprosium, cobalt and aluminum. However, the remanence and energy products were substantially reduced for vanadium-containing magnet samples. These test results show that only the Nd-Dy-Fe-Co-B-Al-Zr magnet sample satisfies the requirements of high performance magnetic properties and excellent corrosion resistance. Since the Nd-Dy-Fe-Co-B-Al-Zr alloy produced a magnet with a combination of high magnetic properties and excellent corrosion resistance, the magnetic properties and corrosion resistance were
The effects of aluminum and zirconium in the -Dy-Fe-Co-B based alloys were investigated with the three alloy compositions reported in Table 3.

[0014]

[Table 3]

The alloy was made into a magnet by the powder metallurgy method described above. Some of the alloy powders were mixed with 0.1% zinc stearate prior to jet mill micronization and others were jet milled without zinc stearate. To obtain anisotropy, when these magnets are aligned by the use of a magnetic field,
Coils different from those used in the arrangement of samples in Table 1 were used. Compared to the samples in Table 1, this resulted in higher fields and higher remanence. After sintering the compression molding at 1000 ° C., the magnet was heat treated at 890 ° C., gradually cooled at 20 ° C./min to 500 ° C., then rapidly → gas cooled. The magnet sample was then aged at 610 ° C for 1 hour. As shown in Table 4, magnets made from pre-alloyed powder particles mixed with 0.1% zinc stearate have a lower weight loss than magnets made from unmixed particles. showed that.

[0016]

[Table 4]

Also, the coercivity of these alloys increased slightly as a result of mixing with zinc stearate. 0.35
% When aluminum is added to the Nd-Dy-Fe-Co- B alloy, the coercivity is increased about 2KO _e, corrosion resistance was slightly improved. When both aluminum (0.35%) and zirconium (1.0%) were added to the same alloy composition, both coercivity and corrosion resistance were significantly improved. This is Nd-Dy
It shows the importance of zirconium when added to the -Fe-Co-B alloy composition. To determine the effect of cobalt and aluminum on both coercivity and corrosion resistance, Nd-Fe-B alloys containing zirconium were made by varying the cobalt and aluminum additions. These compositions are shown in Table 5.
Is shown in.

[0018]

[Table 5]

The weight loss as a function of corrosion resistance and the magnetic properties of the magnet samples of Table 5 after autoclave testing, as affected by cobalt and aluminum content and zinc stearate mixing, are shown in Table 6. Nd-Fe-B magnets containing zirconium or a combination of zirconium and aluminum show relatively low coercivity and clearly good corrosion resistance. Cobalt Nd-Fe
Simultaneous addition to the --B--Zr--Al alloy substantially improves both coercivity and corrosion resistance. It contains zirconium
It has been confirmed that cobalt is an important element in Nd-Fe-B permanent magnets. Alloy RT18 (Nd-Fe-B-Al-Zr)
And the corrosion resistance of alloy RT20 (Nd-Fe-B-Zr) is affected by the zinc stearate mixture, but sample RT19
The corrosion resistance of (Nd-Fe-Co-B-Al-Zr) was not affected by the zinc stearate admixture, indicating a significant combination of magnetic properties and corrosion resistance.

[0020]

[Table 6]

As shown in Table 7, Nd-Fe-Co-B-Al
An alloy of -Zr was made for comparison with the same composition without aluminum or zirconium. These compositions are shown in Table 7.

[0022]

[Table 7]

As shown in Table 8, the loss of zirconium or aluminum results in the deterioration of magnetic properties, especially the intrinsic coercivity. When zirconium is shed from the alloy,
Corrosion resistance is also deteriorated. Therefore, it appears that cobalt, zirconium and aluminum must be present in combination in order to obtain the desired combination of magnetic properties and corrosion resistance according to the invention.

[0024]

[Table 8]

Table 9 shows the magnetic properties and corrosion rates of the alloy compositions reported as a function of zirconium content. When the zirconium content is increased from 0 to 1%,
Corrosion rate decreases rapidly with zirconium content of 1% and 2
It can be seen that the weight loss is almost zero, varying between%. When zirconium exceeds 3%, the corrosion rate gradually increases. The corrosion rate is further reduced when the alloy is mixed with 0.1% zinc stearate prior to jet milling. When the zirconium content increases from 0 to 0.5%, the coercivity increases and the zirconium content increases to 0.5.
The maximum is reached when changing between% and 1.5%. When Jirurukoniumu content Kos 2.0%, the coercivity rapidly reduced early, the zirconium content is 3.0% or more, equal to or less than 1 KO _e.

[0026]

[Table 9]

[0027]

[Table 10]

Table 10 shows the magnetic properties and corrosion rates of the reported alloys as a function of cobalt content. The magnet samples in Table 10 were made from powder mixed with 0.1% zinc stearate. With a small amount of cobalt, such as 2.5%, the corrosion rate of the sample decreases rapidly. When the cobalt content is in the range of 2.5% to 25%, the reported weight loss is almost zero. Cobalt content from 0
The coercivity rapidly increases with increasing 2.5% and 5.0%. Further increases in cobalt content up to 15% do not significantly change the coercivity. Within the range of 2.5% to 15%, the remanence does not change. When the cobalt content exceeds 20%, the remanence is somewhat reduced, and the intrinsic coercivity is dramatically reduced.

[0029]

[Table 11]

Table 11 shows the magnetic properties and corrosion rates of the reported alloys as a function of aluminum content. The magnet samples were made from powder mixed with 0.1% zinc stearate. Regardless of aluminum content
The corrosion rate of the sample is close to zero weight loss. However, the magnetic properties of the alloy samples are highly dependent on the aluminum content. When aluminum was increased from 0 to 0.2%, the coercivity increased rapidly and then the aluminum content was further reduced to 0.2%.
Increasing gradually up to 5%. Increasing the aluminum further to 1.2% slightly reduces the coercivity. The remanence and energy product are the same when the aluminum content is in the range of 0 to 0.6%. Further increases in aluminum begin to reduce remanence and energy products. Aluminum is 1.2
Beyond%, the remanence and energy product are substantially reduced.

[0031]

[Table 12]

The neodymium, iron and boron magnets with cobalt, zirconium and aluminum additives according to the invention were made by replacing some of the neodymium with dysprosium. These magnet samples were made from powder mixed with 0.1% zinc stearate. As can be seen from Table 12, the corrosion rate of the alloy is not affected by the dysprosium content. However, the dysprosium content is 0
To 3%, the intrinsic coercivity increases at a rate of about 3 KO _e / 1 wt% dysprosium. This indicates that a very high coercivity magnet can be made by adding a small amount of dysprosium to this alloy composition. The remanence and energy product did not change until dysprosium was increased to 2%. Further increases in dysprosium begin to reduce remanence and energy products.

[0033]

[Table 13]

The effects of oxygen, carbon and nitrogen on magnetic properties and corrosion resistance were investigated for the particular compositions shown in Table 13. These alloys were jet mill micronized in the presence and absence of 0.1% zinc stearate. Some of the magnet samples were made from the jet milled powder and others were made from the powder that had been oxidised by air bleeding for 4 hours. The magnet samples were measured for magnetic properties and tested for corrosion in an autoclave environment for 240 hours.

[0035]

[Table 14]

As shown in Table 14, the coercivity number of zirconium-containing magnets is significantly affected by the oxygen content, while that of magnets without zirconium is not affected by the oxygen content. In particular, when the oxygen content exceeds 0.5%, the RT18 magnet sample shows a significant loss of coercivity,
The T30 sample showed more than half the loss of coercivity. This indicates that high oxygen content is detrimental to the magnetic properties of these zirconium containing magnets. With a zirconium-free magnet (RT25), an increased oxygen content of about 0.5% is beneficial as it improves corrosion resistance without degrading magnetic properties. Addition of zinc stearate prior to diet mill micronization generally increases carbon content and improves corrosion resistance. The remanence is also improved. Intrinsic coercivity is initially increased and begins to decrease gradually when the carbon content exceeds 0.1%.

[0037]

[Table 15]

[0038]

[Table 16]

However, a Zr-containing magnet containing no Co (R
T18) has lost most of its coercivity value, but when the oxygen content increased above 0.5% in the magnet, 5% Co and 1%
It is noted that the Zr containing magnet (RT30) lost only about half its coercivity value. This suggests that increased Co would reduce the deleterious effects of oxygen in Zr-containing magnets. Therefore, as shown in Table 15, two alloys were made with increased Co contents of 7.5 and 10%. The alloy was jet milled with or without the addition of 0.1% zinc stearate. The jet-milled powder bleedi air for 8 and 16 hours prior to molding.
ng) to oxidize. As shown in Table 15, by air breathing into the powder, the oxygen content was 0.
It was increased from 1% to 0.2% to 0.6% to 0.8%.

Table 16 shows the magnetic properties of high Co content magnets with different oxygen contents. When the oxygen content exceeds 0.6%, the density starts to decrease and the coercivity gradually decreases. Unlike the 5% Co-containing magnets, the detrimental effect of oxygen on the coercivity of the higher Co-containing magnets is not significant. Therefore, in a Zr-containing alloy, when the Co content is 7.5%, the oxygen content is 0.8% without significantly affecting the magnetic properties.
Or it can be increased up to 1.0%. When Co approaches 10%,
The magnetic properties (coercivity) begin to decrease. Tables 13 and 14
As shown in, the corrosion resistance is significantly improved by adding 5% Co to the Zr-containing magnet. Increasing the oxygen content in the alloy containing 5% Co (RT30) does not affect the corrosion resistance. Increasing the Co content up to 7.5% and 10% results in even better corrosion resistance, as shown in Table 10. Therefore, when the Co content is about 7.5% to 10%, the detrimental effect of high oxygen on the magnetic properties of Zr-containing alloys is extinguished and corrosion resistance is still excellent.

[0041]

[Table 17]

[0042]

[Table 18]

The alloys for permanent magnets according to the invention not only exhibit excellent corrosion resistance and magnetic properties, as demonstrated by the data and discussed above, but are also characterized by their ease of processing into permanent magnets. ing. Most neodymium, iron and boron permanent magnet alloys containing cobalt are
In order to obtain the desired high coercivity value, rapid cooling from the sintering temperature and post-sintering heat treatment temperature is required as well as a narrow aging temperature range. The rapid cooling and narrow aging temperature range make it difficult to use conventional manufacturing equipment for mass production of magnets from these compositions. Table 1 for alloy compositions according to the invention
Against normal rapid cooling from sintering and post-sintering heat treatment temperatures, as shown by the data in 7 and 18,
High coercivity was obtained using slow cooling at a rate of about 20 ° C / min. As shown in the data in Tables 17 and 18, the aging treatment is 1, 2 or 3 hours, 580 ° C to 700 ° C.
Coercivity is relatively independent of aging temperature and time when performed in the temperature range of. With these alloys of the invention, due to slow cooling from sintering and heat treatment temperatures, high coercivity will be obtained by aging treatment within a wide temperature range, so these alloys can be produced using conventional production equipment. , Would be easily manufactured into permanent magnets with high magnetic properties and corrosion resistance.

All percentages are by weight unless otherwise noted.
And the temperature is in degrees Celsius. The "Nd" used here
_The term " ₂ Fe ₁₄ B type magnet phase" is defined as the primary phase of a permanent magnet alloy in a primary phase with a tetragonal crystal structure, where Nd is the main rare earth element and is limited to Dy and Pr. Although not included, Fe is a main transition element having any additional rare earth element, and has any additional transition element including but not limited to Co, Al and Zr, and B.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location H01F 1/08 B 41/02 G 8019-5E (72) Inventor Floyd E. Camp Pennsylvania, United States 15085 Trough Aude Junine Coat 102

Claims (43)

[Claims] 1. Most Nd ₂ Fe ₁₄ B type permanent magnet phases, 2.
5% to 20% by weight Co, 0.1% to 1.2% by weight
Al and 0.5 wt% to 3 wt% Zr, essentially Nd-Fe-
An alloy for permanent magnets consisting of B. 2. The alloy for permanent magnets according to claim 1, wherein Zr is in the range of 0.5% by weight to 2% by weight. 3. The alloy for permanent magnets according to claim 1, wherein Co is in the range of 2.5% by weight to 15% by weight. 4. The alloy for permanent magnets according to claim 1, wherein Al is in the range of 0.2% by weight to 1.2% by weight. 5. The alloy for permanent magnets according to claim 1, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 6. Zr is in the range of 0.5% to 2% by weight, Co is in the range of 2.5% to 15% by weight,
The alloy for permanent magnets according to claim 1, wherein Al is in the range of 0.2% by weight to 1.2% by weight. 7. The alloy for permanent magnets according to claim 6, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 8. Most (Nd-Dy) ₂ Fe ₁₄ B type permanent magnet phases, 2.5 wt% to 20 wt% Co, 0.1 wt% to 1.
2 wt% Al and 0.5 wt% to 3 wt% Zr, 5 wt%
An alloy for permanent magnets consisting essentially of Nd-Fe-B with an amount of Dy not exceeding 9. The permanent magnet alloy according to claim 8, wherein Zr is in the range of 0.5% by weight to 2% by weight. 10. The alloy for permanent magnets according to claim 8, wherein Co is in the range of 2.5% by weight to 15% by weight. 11. The alloy for permanent magnets according to claim 8, wherein Al is in the range of 0.2% by weight to 1.2% by weight. 12. The alloy for permanent magnets according to claim 8, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 13. Zr is in the range 0.5% to 2% by weight, Co is in the range 2.5% to 15% by weight, and Al is 0.2% to 1.% by weight. The permanent magnet alloy according to claim 8, which is in the range of 2% by weight. 14. The alloy for permanent magnets according to claim 13, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 15. Most of the Nd ₂ Fe ₁₄ B type permanent magnet phases,
2.5 wt% to 20 wt% Co, 0.1 wt% to 1.2 wt% Al, 0.5 wt% to 3 wt% Zr and oxygen of 1.0 wt% or less, essentially An alloy for permanent magnets consisting of Nd-Fe-B. 16. The permanent magnet alloy of claim 15, wherein Zr is in the range of 0.5% to 2% by weight. 17. The alloy for permanent magnets according to claim 15, wherein Co is in the range of 2.5% by weight to 15% by weight. 18. The alloy for permanent magnets according to claim 15, wherein Al is in the range of 0.2% by weight to 1.2% by weight. 19. The alloy for permanent magnets according to claim 15, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 20. Zr is in the range 0.5% to 2% by weight, Co is in the range 2.5% to 15% by weight, and Al is 0.2% to 1.% by weight. The alloy for permanent magnets according to claim 15, which is in the range of 2% by weight. 21. The alloy for permanent magnets according to claim 20, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 22. Most (Nd-Dy) ₂ Fe ₁₄ B type permanent magnet phases, from 2.5 wt% to 20 wt% Co, from 0.1 wt%
1.2 wt% Al, 0.5 wt% to 3 wt% Zr, and oxygen of 1.0 wt% or less and Dy in an amount not exceeding 5 wt%
An alloy for permanent magnets, which essentially consists of Nd-Fe-B. 23. The alloy for permanent magnets according to claim 22, wherein Zr is in the range of 0.5% by weight to 2% by weight. 24. The alloy for permanent magnets according to claim 22, wherein Co is in the range of 2.5% by weight to 15% by weight. 25. The permanent magnet alloy of claim 22, wherein Al is in the range of 0.2% to 1.2% by weight. 26. The alloy for permanent magnets according to claim 22, wherein Al is in the range of 0.2% by weight to 0.6% by weight. 27. Zr is in the range 0.5% to 2% by weight, Co is in the range 2.5% to 15% by weight, and Al is 0.2% to 1.% by weight. The alloy for permanent magnets according to claim 22, which is in the range of 2% by weight. 28. The permanent magnet alloy of claim 27, wherein Al is in the range of 0.2 wt% to 0.6 wt%. 29. A method of manufacturing a permanent magnet, the method comprising: most Nd ₂ Fe ₁₄ B type permanent magnet phase, 2.5 wt% to 20 wt% Co, 0.1 wt% to 1 wt%. .2 wt% Zr, and 0.5 wt% to 3 wt% Zr, essentially Nd-Fe-B
To form prealloyed particles of an alloy for permanent magnets, magnetically aligning the particles, and 950 ° C to 1100 ° C.
Consolidation of the particles to produce a completely dense body, including sintering at temperatures in the range of 30 to 120 minutes, 850 ° C to 9 minutes.
The body is heated at a temperature of 50 ° C. and cooled at a rate of 5 ° C.-50 ° C./min to 400 ° C.-550 ° C., then 50
A method for producing a permanent magnet, which comprises aging the object at a temperature within a range of 0 ° C to 750 ° C. 30. The method of claim 29, wherein the aging is at a temperature within the range of 550 ° C to 700 ° C. 31. The method of claim 29 or 30, wherein the particles are mixed with a carbon-containing lubricant and ground to reduce its size prior to said compacting. 32. The method of claim 29 or 30, wherein the particles are mixed with a lubricant of an organometallic compound and milled to reduce its size prior to said compacting. 33. The method of claim 32, wherein the lubricant is zinc stearate. 34. The method of claim 29 or 30, wherein prior to said compacting, the particles are mixed with a hydrocarbon compound lubricant and ground to reduce its size. 35. The alloy for permanent magnets comprises most (Nd-
Dy) ₂ Fe ₁₄ B permanent magnet phase, 2.5 wt% to 20 wt% Co,
0.1 wt% to 1.2 wt% Al, and 0.5 wt% to 3
31. A process according to claim 29 or 30 which consists essentially of Nd-Fe-B with a wt% Zr and an amount of Dy not exceeding 5 wt%. 36. The alloy for permanent magnets comprises most (Nd-
Dy) ₂ Fe ₁₄ B permanent magnet phase, 2.5 wt% to 20 wt% Co,
0.1 wt% to 1.2 wt% Al, and 0.5 wt% to 3
32. The method of claim 31, consisting essentially of Nd-Fe-B with wt% Zr and an amount of Dy not exceeding 5 wt%. 37. The alloy for permanent magnets comprises most of the (Nd-
Dy) ₂ Fe ₁₄ B permanent magnet phase, 2.5 wt% to 20 wt% Co,
0.1 wt% to 1.2 wt% Al, and 0.5 wt% to 3
33. The method of claim 32, which consists essentially of Nd-Fe-B with a weight percent Zr of not more than 5 weight percent Dy. 38. The alloy for permanent magnets comprises most of the (Nd-
Dy) ₂ Fe ₁₄ B permanent magnet phase, 2.5 wt% to 20 wt% Co,
0.1 wt% to 1.2 wt% Al, and 0.5 wt% to 3
34. The method of claim 33 consisting essentially of Nd-Fe-B with an amount of Dy of not more than 5% by weight Zr. 39. The alloy for permanent magnets comprises most of the (Nd-
Dy) ₂ Fe ₁₄ B permanent magnet phase, 2.5 wt% to 20 wt% Co,
0.1 wt% to 1.2 wt% Al, and 0.5 wt% to 3
35. The method of claim 34, which consists essentially of Nd-Fe-B with wt% Zr and an amount of Dy not exceeding 5 wt%. 40. The alloy for permanent magnets comprises most of Nd ₂ Fe.
₁₄ B permanent magnet phase, 2.5% to 20% by weight Co, 0.1% to 1.2% by weight Al, 0.5% to 3% by weight Zr, and 1% by weight or less of oxygen In the following, essentially Nd-Fe-
31. The method of claim 29 or 30 comprising B. 41. The alloy for permanent magnets comprises most of the Nd ₂ Fe.
₁₄ B permanent magnet phase, 2.5% to 20% Co, 0.1% to 1.2% Al, 0.5% to 3% Zr, and 1% or less oxygen. And essentially Nd-Fe-B
32. The method of claim 31, comprising: 42. The alloy for permanent magnets comprises most of the Nd ₂ Fe.
₁₄ B permanent magnet phase, 2.5% to 20% Co, 0.1% to 1.2% Al, 0.5% to 3% Zr, and 1% or less oxygen. And essentially Nd-Fe-B
33. The method of claim 32, which comprises: 43. The alloy for permanent magnets comprises most of the Nd ₂ Fe.
₁₄ B permanent magnet phase, 2.5% to 20% by weight Co, 0.1% to 1.2% by weight Al, 0.5% to 3% by weight Zr, and 1% by weight or less oxygen. And essentially Nd-Fe-
34. The method of claim 33, comprising B.