SOFT AND HARD MAGNETIC MATERIALS
Depending upon the hysteresis area/loss, the ferromagnetic materials are classified into two types. They are soft magnetic materials and hard magnetic materials.
(i) Soft magnetic materials:
The ferromagnetic materials which are easily magnetised and demagnetised are known as soft magnetic materials. Their properties are given below.
Properties:
(a) Soft magnetic materials have small/steep hysteresis loop.
(b) They have less hysteresis loss.
(c) They can be easily magnetised and demagnetised.
(d) They have high susceptibility and permeability.
(e) They have low coercivity and high retentivity.
(f) They have high resistivity and they requires low magnetic field for magnetization.
Applications: Soft magnetic materials are used in electric devices, magnetic cores of transformers. They are also using in motors, relays, sensors, microwave isolators.
Examples: Iron-Silicon alloy, Nickel- iron alloy, Iron-Cobalt alloys.
(ii) Hard magnetic materials:
The ferromagnetic materials which are difficult to magnetize and demagnetize are known as hard magnetic materials.
Properties:
(a)Hard magnetic materials have large hysteresis loop.
(b)They have more hysteresis loss.
(c)They need high strong magnetic field to magnetize and demagnetize.
(d)They have low susceptibility and permeability.
(e)They have high coercivity and high retentivity.
Applications:
Hard magnetic materials used to make permanent magnets. They are used in the dc
motors, measuring devices, speedometers, sensors in automobiles etc.
Examples: Carbon-steel alloy, Tungtern- steel alloy, chromium-steel alloy, alnico alloy etc.