Neodymium Iron Boron (Nd-Fe-B)
Sintered neodymium-iron-boron (Nd-Fe-B) magnets are the most powerful commercialized permanent magnets available today, with maximum energy product ranging from 26 MGOe to 52 MGOe. Nd-Fe-B is the third generation of permanent magnet developed in the 1980s. It has a combination of very high remanence and coercivity, and comes with a wide range of grades, sizes and shapes. With its excellent magnetic characteristics, abundant raw material and relatively low prices, Nd-Fe-B offers more flexibility in designing of new or replace the traditional magnet materials such as ceramic, Alnico and Sm-Co to achieve high efficiency, low cost and more compact devices.
A powder metallurgy process is used in producing sintered Nd-Fe-B magnets. Although sintered Nd-Fe-B is mechanically stronger than Sm-Co magnets and less brittle than other magnets, it should not be used as structural component. Selection of Nd-Fe-B is limited by temperature due to its irreversible loss and moderately high reversible temperature coefficient of Br and Hci. The maximum application temperature is 200 °C for high coercivity grades. Nd-Fe-B magnets are more prone to oxidation than any other magnet alloys. If Nd-Fe-B magnet is to be exposed to humidity, chemically aggressive media such as acids, alkaline solutions salts and harmful gases, coating is recommended. It is not recommended in a hydrogen atmosphere.
| Grade |
Maximum
Energy
Product
BHmax |
Residual
Induction
Br |
Minimum
Intrinsic
Coercivity
Hci |
Coercivity
Hc |
Maximum
Operating
Temp
Tmo |
Curie Temp
Tc |
Coefficient
Induction
20-150 °C]
α |
Coefficient
Coercivity
20-150 °C]
β |
| MGOe |
kG |
kOe |
kOe |
°C |
°C |
% / °C |
% / °C |
| N5211 |
52 |
14.5 |
11 |
10.6 |
50 |
310 |
-0.12 |
-0.65 |
| N5011 |
50 |
14.3 |
11 |
10.6 |
50 |
310 |
-0.12 |
-0.63 |
| N4811 |
48 |
13.9 |
11 |
10.6 |
50 |
310 |
-0.12 |
-0.63 |
| N4511 |
45 |
13.6 |
11 |
10.5 |
50 |
310 |
-0.12 |
-0.63 |
| N4812 |
48 |
14.0 |
12 |
11.4 |
80 |
310 |
-0.12 |
-0.63 |
| N4512 |
45 |
13.5 |
12 |
11.3 |
80 |
310 |
-0.12 |
-0.63 |
| N4212 |
42 |
13.5 |
12 |
11.2 |
80 |
310 |
-0.12 |
-0.63 |
| N4012 |
40 |
12.8 |
12 |
11.1 |
80 |
310 |
-0.12 |
-0.63 |
| N3812 |
38 |
12.4 |
12 |
10.9 |
80 |
310 |
-0.12 |
-0.63 |
| N3512 |
35 |
12.0 |
12
|
10.8 |
80 |
310 |
-0.12 |
-0.63 |
| N5014 |
50 |
14.2 |
14 |
12.6 |
80 |
310 |
-0.12 |
-0.63 |
| N4814 |
48 |
13.9 |
14 |
12.4 |
80 |
310 |
-0.12 |
-0.63 |
| N4514 |
45 |
13.6 |
14 |
12.3 |
80 |
310 |
-0.12 |
-0.63 |
| N4214 |
42 |
13.1 |
14 |
12.1 |
80 |
310 |
-0.12 |
-0.63 |
| N4014 |
40 |
12.8 |
14 |
11.8 |
80 |
310 |
-0.12 |
-0.63 |
| N3814 |
38 |
12.4 |
14 |
11.5 |
80 |
310 |
-0.12 |
-0.63 |
| N3514 |
35 |
12.0 |
14 |
11.3 |
80 |
310 |
-0.12 |
-0.63 |
| N3314 |
33 |
11.6 |
14 |
10.9 |
80 |
310 |
-0.12 |
-0.63 |
| N4816 |
48 |
13.8 |
16 |
12.9 |
100 |
320 |
-0.11 |
-0.61 |
| N4516 |
45 |
13.7 |
16 |
12.8 |
100 |
320 |
-0.11 |
-0.61 |
| N4216 |
42 |
13.1 |
16 |
12.4 |
100 |
320 |
-0.11 |
-0.61 |
| N3616 |
36 |
12.2 |
16 |
11.6 |
100 |
320 |
-0.11 |
-0.61 |
| N3216 |
32 |
11.4 |
16 |
10.9 |
100 |
320 |
-0.11 |
-0.61 |
| N4517 |
45 |
13.4 |
17 |
12.7 |
120 |
320 |
-0.11 |
-0.60 |
| N4217 |
42 |
13.0 |
17 |
12.4 |
120 |
320 |
-0.11 |
-0.60 |
| N4017 |
40 |
12.8 |
17 |
12.3 |
120 |
320 |
-0.11 |
-0.60 |
| N3817 |
38 |
12.4 |
17 |
11.9 |
120 |
320 |
-0.11 |
-0.60 |
| N3517 |
35 |
12.0 |
17 |
11.5 |
120 |
320 |
-0.11 |
-0.60 |
| N3317 |
33 |
11.6 |
17 |
11.2 |
120 |
320 |
-0.11 |
-0.60 |
| N3017 |
30 |
11.0 |
17 |
10.6 |
120 |
320 |
-0.11 |
-0.60 |
| N4220 |
42 |
13.0 |
20 |
12.5 |
150 |
330 |
-0.11 |
-0.58 |
| N4020 |
40 |
12.8 |
20 |
12.4 |
150 |
330 |
-0.11 |
-0.58 |
| N3820 |
38 |
12.4 |
20 |
12.0 |
150 |
330 |
-0.11 |
-0.58 |
| N3520 |
35 |
12.0 |
20 |
11.6 |
150 |
330 |
-0.11 |
-0.58 |
| N3320 |
33 |
11.6 |
20 |
11.3 |
150 |
330 |
-0.11 |
-0.58 |
| N3020 |
30 |
11.1 |
20 |
10.8 |
150 |
330 |
-0.11 |
-0.58 |
| N4221 |
42 |
13.0 |
21 |
12.5 |
150 |
330 |
-0.11 |
-0.55 |
| N4021 |
40 |
12.8 |
21 |
12.4 |
150 |
330 |
-0.11 |
-0.55 |
| N3821 |
38 |
12.6 |
21 |
12.3 |
150 |
330 |
-0.11 |
-0.55 |
| N3521 |
35 |
11.9 |
21 |
11.5 |
150 |
330 |
-0.11 |
-0.55 |
| N3021 |
30 |
11.1 |
21 |
10.8 |
150 |
330 |
-0.11 |
-0.55 |
| N3825 |
38 |
12.5 |
25 |
12.2 |
180 |
340 |
-0.10 |
-0.55 |
| N3525 |
35 |
12.0 |
25 |
11.6 |
180 |
340 |
-0.10 |
-0.55 |
| N3325 |
33 |
11.6 |
25 |
11.3 |
180 |
340 |
-0.10 |
-0.55 |
| N3025 |
30 |
11.1 |
25 |
10.8 |
180 |
340 |
-0.10 |
-0.55 |
| N2825 |
28 |
10.6 |
25 |
10.4 |
180 |
340 |
-0.10 |
-0.55 |
| N3530 |
35 |
12.0 |
30 |
11.7 |
200 |
360 |
-0.08 |
-0.55 |
| N3330 |
33 |
11.6 |
30 |
11.4 |
200 |
360 |
-0.08 |
-0.55 |
| N3030 |
30 |
11.0 |
30 |
10.7 |
200 |
360 |
-0.08 |
-0.55 |
| N2830 |
28 |
10.7 |
30 |
10.5 |
200 |
360 |
-0.08 |
-0.55 |
| Typical Physical Properties |
| Curie Temperature |
320 - 380°C |
| Coefficient of Thermal Expansion - Perpendicular |
-1.0 - -3.0 x 10-6 °C-1 |
| Coefficient of Thermal Expansion - Parallel |
+5.0 - +8.0 x 10-6 °C-1 |
| Electrical Resistivity |
120 - 160 µΩ·cm |
| Density |
7.4 - 7.8 g·cm-3 |
| Vicker's Hardness |
550 - 650 HV |
| Young's Modulus |
150 - 170 kN·mm-2 |
| Bending Strength |
0.18 - 0.29 kN·mm-2 |
| Compressive Strength |
0.8 - 1.0 kN·mm-2 |
|