What is permalloy?

Permalloy: A Soft Ferromagnetic Alloy

Permalloy is a nickel-iron ferromagnetic alloy, with about 80% nickel and 20% iron content. It is notable for its very high magnetic permeability, low coercivity, near zero magnetostriction, and significant anisotropic magnetoresistance.

• Composition: Typically 80% Nickel (Ni) and 20% Iron (Fe). Variations in composition can affect its magnetic properties.

• Magnetic%20Permeability: Permalloy exhibits exceptionally high magnetic permeability, meaning it can easily concentrate magnetic flux. This makes it ideal for applications requiring efficient magnetic shielding or core materials.

• Coercivity: It has a very low coercivity, indicating that it is easily magnetized and demagnetized. This is crucial for applications where the material needs to respond quickly to changes in the magnetic field.

• Magnetostriction: Permalloy has near-zero magnetostriction. Magnetostriction is the property of a ferromagnetic material that causes it to change its shape or dimensions during magnetization. The absence of this property in permalloy is important in applications where dimensional stability is crucial.

• Anisotropic%20Magnetoresistance: Permalloy exhibits anisotropic magnetoresistance, meaning its electrical resistance changes depending on the angle between the current and the magnetization direction. This property is utilized in magnetic sensors.

• Applications: Due to its unique magnetic properties, permalloy is widely used in:

  • Magnetic shielding to protect sensitive electronic components from external magnetic fields.
  • Transformer cores.
  • Magnetic recording heads.
  • Magnetic sensors.
  • Compass needles.
  • Thin film magnetic memories.

• Forms: Permalloy is often used in thin films, which can be deposited onto substrates to create desired magnetic properties in microelectronic devices. It can also be produced in bulk form.

• Processing: The magnetic properties of permalloy are very sensitive to heat treatment. Annealing in a magnetic field is often used to optimize its magnetic permeability and minimize coercivity.