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| PRODUCT DATA of Mumetal |
| Material | Mumetal |
| Product Datasheet | hyNu80 |
| General Information | MuShield high permeability magnetic shielding material is a non-oriented 80% nickel-iron-molybdenum alloy which offers extremely high initial permeability and maximum permeability with minimum hysteresis loss. The high permeability makes mu-metal very effective at screening static or low-frequency magnetic fields, which cannot be attenuated by other methods. |
| Use in Spacecraft | Mumetal shields are often made of several enclosures one inside the other, each of which successively reduces the field inside it. |
| Processing and Assembly | Mu-metal parts require heat treatment after forming — annealing in a magnetic field in hydrogen atmosphere, which reportedly increases the magnetic permeability about 40 times. The annealing alters the material's crystal structure, aligning the grains and removing some impurities, especially carbon, which obstruct the free motion of the magnetic domain boundaries. Bending or mechanical shock after annealing may disrupt the material's grain alignment, leading to a drop in the permeability of the affected areas, which can be restored by repeating the hydrogen annealing step. |
| Precautions | In order to achieve shielding at cryogenic temperatures it would be necessary to have a special layer made of cryogenic mumetal. The permeability decreases as the temperature drops, because of reduced molecular mobility. |
| Chemical Composition | 80Ni-4.2Mo-0.5Mn-0.35Si-0.02C-rem Fe |
| Name of Manufacturer | Mumetal
PO Box 5045, Manchester, New Hampshire, 03108-5045 603.666.4433 603.666.4013 info@mumetal.com http://www.mumetal.com Carpenter Technology 101 West Bern Street, Reading PA 1960, USA 800-654-6543 877-356-2225 webmaster@cartech.com http://www.cartech.com Carpenter Technology (UK) Ltd. 3 Adams Way, Arden Forest Industrial Estate, Springfield Business Park, Alcester, Warwickshire, UK +44 (0)1789 767340 +44 (0)1789 767341 webmaster@cartech.com |
| EXPERIENCE IN PRACTICE |
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| Development Status | Commercial Product |
| Equivalent Designations | HYMu 80 HyMy80 permaloy mu-metal |
| Space Experience | Good |
| PHYSICAL PROPERTIES |
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| Specific Gravity | 8.74 |
| Magnetic Properties | Ferromagnetic |
| Curie Temperature | 460 °C |
| ELASTIC PROPERTIES |
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| Tensile Modulus | 230 GPa |
| Poisson Ratio | 0.29 |
| ELECTRICAL PROPERTIES |
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| Electrical Volume Resistivity | 5.8e-7 ohm.m |
| THERMAL PROPERTIES |
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| Thermal Conductivity | 34.6 W/m.K |
| Thermal Expansion Coefficient | 10.8 to 12.4 μstrain/°C |
| Specific Heat | 0.494 J/g.K |
| Melting Range | 1450 °C |
| RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY |
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| Stress Corrosion Status | Class 3
according to ECSS-Q-ST-70-37C Data Quality: Preliminary Design Data |
| EMF vs SCE | -0.26 V |
| Machinability | Good. Cutting by EDM or waterjet is recommended. |
| Welding | Good, but must be fully heat treated after welding. |
| SPECIAL RECOMMENDATIONS |
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| Special Recommendations | Coercive force from H=1.0 Oe, Oersted 0.008 to 0.02 Hysteresis loss from H=1.0 Oe, erg/cm3 per cycle 18 to 24 |