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PRODUCT DATA of Mumetal
MaterialMumetal
Product DatasheethyNu80
General InformationMuShield 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 SpacecraftMumetal shields are often made of several enclosures one inside the other, each of which successively reduces the field inside it.
Processing and AssemblyMu-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.
PrecautionsIn 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 Composition80Ni-4.2Mo-0.5Mn-0.35Si-0.02C-rem Fe
Name of ManufacturerMumetal
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
Development StatusCommercial Product
Equivalent DesignationsHYMu 80 HyMy80 permaloy mu-metal
Space ExperienceGood
PHYSICAL PROPERTIES
Specific Gravity8.74
Magnetic PropertiesFerromagnetic
Curie Temperature460 °C
ELASTIC PROPERTIES
Tensile Modulus230 GPa
Poisson Ratio0.29
ELECTRICAL PROPERTIES
Electrical Volume Resistivity5.8e-7 ohm.m
THERMAL PROPERTIES
Thermal Conductivity34.6 W/m.K
Thermal Expansion Coefficient10.8 to 12.4 μstrain/°C
Melting Range1450 °C
Specific Heat0.494 J/g.K
RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY
Stress Corrosion StatusClass 3
according to ECSS-Q-ST-70-37C
Data Quality: Preliminary Design Data
EMF vs SCE-0.26 V
MachinabilityGood. Cutting by EDM or waterjet is recommended.
WeldingGood, but must be fully heat treated after welding.
SPECIAL RECOMMENDATIONS
Special RecommendationsCoercive 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