HYMu80 Permalloy

HYMU 80 is a FeNi soft magnetic alloy with very high initial permeability. HyMu 80 is suitable for a wide range of applications. The material's high permeability and low hysteresis loss and its shielding properties make it a suitable choice for protecting electronic components from stray or low frequency magnetic fields. HYMU 80 is widely used in magnetic shielding applications to isolate electronic components from magnetic interference for optimal functionality

Hymu 80 is a nickel-iron-molybdenum alloy containing 80% nickel, with very high starting permeability and maximum permeability with minimal hysteresis loss. It is mainly used for high performance magnetic shielding, current sensing magnetic rings, etc. HYMU 80 shielding alloy Permalloy, HY MU 80, MAG 7904, MIL N 14411 C, COMP. 1 OR ASTM A753-78 Applications Hymu 80 is primarily used to make transformer cores with wound toroids and laminations to meet compatibility and weight requirements. It is also used as a shield to protect electrical components from stray magnetic fields. Physical properties (annealed state) Specific gravity: 8.74 g/cm Density: 0.316lb/in3 Average specific heat: 0.1180 Btu/lb/°F Curie temperature: 860 F (461 C) Melting Distance: 2650°F (1472°C) Coefficient of resistance: 21.1°C 580.0 micro-ohm-mm 70°F, 349.0 ohm-cir-mil/ft Thermal conductivity: 34.60 W/m/K Coefficient of Thermal Expansion: 13 cm/cm/degree C x 10-6 between 30 & 204 C Modulus of elasticity: 871°C annealed, tensile state 31.4*103 ksi Cold drawn, tensile condition 33.7*103 ksi 1177°C, hydrogen annealed, in tension 33.3*103 ksi Magnetic properties Coercive magnetic force: 0.637 to 1.59 A/m Maximum magnetic flux: 200000 Maximum magnetic permeability: 200000 Residual magnetic induction: 0.3500 T Hysteresis loss: 1.80E-6 to 2.40E-6 J/cm³/cycle Shielding properties Because of its extremely high magnetic permeability and very low resistance to magnetism (coercivity), HYMU 80 is particularly suitable for magnetic shielding applications. The annealed, deep-stamping quality strip is processed into shields by bending, stamping and spinning processes. Spot welding or tungsten gas welding can be used where connections are required. Welding can be done with or without a base metal welding rod. For optimum shielding performance, the shield needs to be exposed to a temperature of 1900°F (1040°C) or higher after fabrication. (1040°C) or higher (see Heat Treatment section for details). In general, the higher the annealing temperature, the better the material permeability and shielding performance. To determine the shielding capability of the material: The material is machined into an open cylinder shield. A magnetic sensor is placed in the center of a uniform magnetic field, such as that generated by a Helmholtz coil. The attenuation rate A is the ratio of the reading E1 of the magnetic sensor to the reading E2 with the shield added, i.e. A = E1/E2 This is the shielding effect measured under specific test conditions. The shielding effect is affected by the shield thickness, the shield length to diameter ratio and the Helmholtz coil diameter. The detailed measurement method is described in ASTM A698, "Variable Current Test Methods for Magnetic Shielding". Heat Treatment Intermediate Annealing: To remove stress and restore material to suitability for stamping, spinning, forming, bending or similar operations, anneal at 1450/1850°F (788/1010°C) for not more than one hour. Because of its high nickel content, HYMU 80 readily absorbs carbon, sulfur, oxygen and other contaminants from the heat treat furnace gases. Intermediate annealing should be performed in a dissociated ammonia, hydrogen, vacuum or inert gas furnace. Hydrogen annealing: To achieve the softest and optimum magnetic properties, as well as electrical properties, HYMU 80 should be annealed in a dry, all-hydrogen atmosphere without oxygen and with a dew point below -40°F (-40°C) at 2050/2150°F (1121/1177°C) for 2 to 4 hours. The furnace is cooled to 1100°F (593°C). From 1100 to 700°F (593 to 371°C), cooling at 350 to 600°F (194 to 334°C) per hour. Oil, grease, lacquer and all other contaminants must be removed prior to annealing. Individual parts should be separated from each other by inert holding powders (magnesium and aluminum oxides) during the full hydrogen annealing process. Vacuum heat treatment can also be used, although overall it is slightly inferior in terms of magnetic properties compared to a dry all-hydrogen atmosphere. Hymu80 is mainly used to make transformer cores with wound toroidal coils and iterations to meet compatibility and weight requirements. It is also used as shielding to protect electrical components from stray magnetic fields.