Permalloy 80

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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:

  • Transformer laminations

  • Relays

  • Recording Heads

  • Deflection and Focusing Yokes

  • Amplifiers

  • Loudspeakers

  • 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.