Iron-nickel based soft magnetic alloys with 30-90% nickel content is collectively referred to as Permalloy. Permalloy is invented in 1914 by physicist Gustav Elmen at Bell Telephone Laboratories and then became a distinguished name of magnetism. Permalloy is notable for its very high magnetic permeability which makes it useful as magnetic core material and magnetic shielding material under the weak magnetic field. Besides high permeability, its other magnetic properties are including low coercivity, near zero magnetostriction, and significant anisotropic magnetoresistance. Grades of Permalloy are typically specified by Arabic numerals 1 + letter J +two numbers. Arabic numerals 1 stand for soft magnet. Letter J that follows represent the precision alloy. The two numbers tagged on the end determine the nickel content in the alloy. The commonly used grades include 1J50, 1J79 and 1J85. In addition to composition range, magnetic performance of Permalloy also can be adjusted by the heat treatment process.
Electromagnetic Properties of Permalloy
| Grade | Condition | Level | Thickness/Diameter | Initial magnetic permeability μ0.08 (mH/m) | Maximum permeability μmax (mH/m) | Coercivity Hc (A/m) | Saturated magnetic flux density Bs (T) |
| 1J50 | Tape | II | 0.10-0.19 | ≥3.8 | ≥43.8 | ≤12 | 1.5 |
| 0.20-0.39 | ≥4.4 | ≥56.3 | ≤10.4 | ||||
| 0.35-0.50 | ≥5.0 | ≥65 | ≤8.8 | ||||
| 0.51-1.00 | ≥5.0 | ≥50 | ≤10 | ||||
| 1.10-2.50 | ≥3.8 | ≥44 | ≤12 | ||||
| I | 0.05-0.20 | ≥12.5 | ≥75 | ≤4.8 | 1.52 | ||
| Bar | – | 10-100 | 3.1 | 31.3 | 14.4 | 1.5 | |
| 1J79 | Tape | II | 0.005 | 15 | 75 | 4.8 | 0.75 |
| 0.01 | 20 | 110 | 3.2 | ||||
| 0.02-0.04 | 25 | 125 | 2.4 | ||||
| 0.05-0.09 | 25 | 150 | 1.6 | ||||
| 0.10-0.19 | 28 | 190 | 1.2 | ||||
| 0.20-0.34 | 31 | 250 | 1.2 | ||||
| 0.35-1.00 | 38 | 280 | 1 | ||||
| 1.10-2.50 | 31 | 230 | 1.2 | ||||
| III | 0.01 | 25 | 150 | 2.4 | 0.73 | ||
| 0.02-0.04 | 31 | 190 | 1.6 | ||||
| 0.05-0.09 | 38 | 250 | 1.2 | ||||
| 0.10-0.19 | 38 | 250 | 1.2 | ||||
| 0.20-0.34 | 38 | 280 | 1 | ||||
| 0.35 | 44 | 310 | 1 | ||||
| Bar | – | 10-100 | 25 | 125 | 2.4 | 0.75 | |
| 1J85 | Tape | II | 0.02-0.04 | 37.5 | 137.5 | 2.4 | 0.70 |
| 0.05-0.09 | 50 | 175 | 1.6 | ||||
| 0.10-0.19 | 62.5 | 225 | 1.2 | ||||
| 0.20-0.34 | 75 | 250 | 1 | ||||
| 0.35 | 68.8 | 325 | 0.7 | ||||
| Bar | – | 10-100 | 37.5 | 125 | 1.6 |
| Grade | Condition | Maximum permeability μmax (mH/m) | Squareness ratio Br/Bm | Coercivity Hc (A/m) | Saturated magnetic flux density Bs (T) |
| 1J34 | Tape | ≥137.5 | ≥0.87 | ≤8 | 1.5 |
| 1J51 | ≥50.0 | ≥0.85 | ≤18 | 1.5 | |
Note:
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| Grade | Condition | Magnetic flux density B under 8000A/m | ||||
| -20℃ | 20℃ | 40℃ | 60℃ | 80℃ | ||
| 1J30 | Tape | 0.40-0.60 | 0.20-0.45 | – | 0.02-0.13 | – |
| 1J31 | 0.60-0.85 | 0.40-0.65 | – | 0.15-0.45 | – | |
| 1J32 | 0.80-1.10 | 0.60-0.95 | – | 0.40-0.75 | – | |
| 1J33 | – | 0.40-0.70 | – | – | 0.10-0.40 | |
| 1J38 | 0.25-0.42 | 0.05-0.24 | -0.015-0.120 | – | – | |
| Note: The above-mentioned data of electromagnetic properties are given based on the tape with a thickness of 0.1-1.00mm. | ||||||