77NMD – Nickel-Molybdenum Soft Magnetic Alloy
General Characteristics
77NMD is a specialized nickel-based soft magnetic alloy with molybdenum addition, featuring unique combination of:
✔ Exceptionally high initial permeability
✔ Minimal coercive force
✔ Low hysteresis losses
✔ Stable characteristics across wide temperature range
Chemical Composition
| Element | Content (%) |
|---|---|
| Ni | 76-78 |
| Mo | 3.8-4.2 |
| Cu | 4.5-5.5 |
| Fe | Balance |
| Mn | ≤0.6 |
| Si | ≤0.3 |
| C | ≤0.03 |
Magnetic Properties
Initial permeability (μi): 100,000-150,000
Maximum permeability (μmax): up to 400,000
Coercive force (Hc): 0.4-0.8 A/m
Saturation induction (Bs): 0.75-0.85 T
Resistivity: 55-60 μΩ·cm
Physical-Mechanical Properties
Density: 8.7 g/cm³
Melting point: ≈1450°C
Hardness (HV): 120-150
Tensile strength: 400-500 MPa
Elongation: 25-35%
Processing Features
Heat Treatment:
Hydrogen annealing at 1100-1200°C
Slow cooling (50-100°C/hour)
Mechanical Processing:
Excellent stamping characteristics
Capable of thin rolling (down to 0.02 mm)
Suitable for complex machining
Main Applications
Precision Instruments:
Sensitive magnetic field sensors
Ultra-precision transformers
Class 0.1-0.05 measuring devices
Special Equipment:
Navigation system components
High-efficiency magnetic shields
Magnetostrictive devices
Electrical Engineering:
Pulse transformer cores
High-Q inductors
Magnetoelectric system components
Comparison with Alternatives
| Parameter | 77NMD | 50N | Permalloy 80 |
|---|---|---|---|
| μi | 100-150k | 20-50k | 50-100k |
| Hc (A/m) | 0.4-0.8 | 1.2-2.0 | 0.8-1.2 |
| Bs (T) | 0.75-0.85 | 1.5-1.6 | 0.7-0.8 |
| Cost | High | Medium | Very High |
Delivery Forms 77NMD
| 77NMD wheel | Diameter 4-300mm |
| 77NMD sheet | Thickness 0.5-20mm |
| 77NMD Tape | Thickness 0.2-2mm |
| 77NMD strip | Thickness 10-50mm |
| 77NMD wire | Diameter 0.5-9mm |
| 77NMD Tube | – Hot Rolled Round Tube diameter 38 or more up to 244.5 mm, thickness from 3 to 25 mm -Cold drawn round tube diameter from 6 to 219.1mm thickness from 0.9 to 14.2mm |
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