Permalloy 80
Permalloy 80 is a highly magnetic nickel-iron-molybdenum alloy, with roughly 80% nickel and 15% iron and 5% molybdenum content. It's useful as a magnetic core material in electrical and electronic equipment. Commercial permalloy alloys typically have relative permeability of around 100,000, compared to several thousand for ordinary steel. It provides maximum magnetic permeabilities and minimal core losses at low field strengths. This vacuum-melted product also offers the advantages of small size and weight in magnetic core and shielding materials for the applications shown below. Other magnetic properties are near zero magnetostriction, and significant anisotropic magnetoresistance.
Permalloy 80 provides high initial and maximum permeabilities with low coercive force, low hysteresis loss, low eddy-current losses, and low magnetostriction, which is critical for industrial applications, allowing it to be used in thin films where variable stresses would otherwise cause a large destructive variation in magnetic properties. Typical applications for this material are:
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Transformer laminations
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Relays
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Recording Heads
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Deflection and Focusing Yokes
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Amplifiers
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Loudspeakers
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Shielding
MAGNETIC PROPERTIES*
Typical D.C. Magnetic Properties:
Saturation Flux Density: 7,500 gausses
Coercive Force from H = 1 oersted: 0.015 oersted
Residual Induction: 3,700 gausses
Hysteresis Loss from Saturation: 9 ergs/cm3/cycle
Permeability @ B = 100: 75,000
Maximum Permeability: 300,000
Minimum Magnetic Permeabilities:
(B = 40 gauss @ 60 Hz)
Thickness μ
.001" 50,000
.002" 55,000
.004" 65,000
.006" 55,000
.014" 50,000
All specimens were ring laminations.
*After appropriate anneal - see below
NOMINAL PHYSICAL PROPERTIES:
Density:
g/cm3 8.74
lb./in3 0.316
Electrical Resistivity:
microhm-cm 58
ohm/cer mil-ft 349
Specific Heat:
cal/g/oC 0.12
Thermal Conductivity:
cal/cm3/sec/oC 0.047
BTU/in/ft2/hr/oF 136
Thermal Expansion:
Coefficient: in/in/oC
(-70 to +200 oC) 12.0 x 10-6
TYPICAL CHEMICAL COMPOSITION:
Nickel 80%
Molybdenum 4.4%
Silicon 0.3%
Manganese 0.5%
Iron Balance
TYPICAL MECHANICAL PROPERTIES:
Cold 'Magnetic'
Rolled Annealed Annealed*
Tensile Strength(ksi): 150 90 80
Yield Strength(ksi): 135 35 30
% Elongation in 2": 2 40 40
*The maximum magnetic properties of Permalloy 80 are best achieved by annealing for 4 hours at 1120oC to 1160oC in a pure dry hydrogen atmosphere (-40oC dew point). Cooling in the 700oC to 300oC range at 3oC to 7oC per minute is recommended. In order to retain the maximum properties this anneal should be done after all manufacturing of the part is completed.
ESPI Metals does not sell Permalloy 80 products in the 'magnetic' annealed condition.