Soft and Hard magnetic materials

SOFT AND HARD MAGNETIC MATERIALS  -  EXAMPLES & USES

Soft magnetic materials

The materials which can be easily magnetised and demagnetised are called Soft magnetic materials

Hard magnetic materials

The materials which are very difficult to magnetise and demagnetise are called hard magnetic materials.

Differences between Soft and Hard magnetic materials:

Soft

1. They can be easily magnetised and demagnetised.

2. Movement of domain wall is easy and hence even for a small applied field large magnetisation occurs.

3. The Hysteresis loop is very narrow as shown in Fig..

4. Loop area is less and hence the hysteresis loss is minimum.

5. Susceptibility and permeability are high

6. Retentivity and Coercivity are small

7. They have low eddy current loss.

8. These materials are free from irregularities like strain or impurities.

9. Examples: Iron, silicon alloys, Ferrites, Garnets etc.

10. Uses: It is used to make the temporary magnets. They are also used in switching devices, electro‒magnets, matrix storage of computers.

Hard

1. They cannot be easily magnetised (or) demagnetised.

2. Movement of domain wall is not easy due to the presence of impurities and hence large field is required for magnetisation.

3. The Hysteresis loop is very broad as shown in Fig.

4. The loop area is large and hence the hysteresis loss is maximum.

5. Susceptibility and permeability are low.

6. Retentivity and Coercivity are large.

7. They have high eddy current loss.

8. These materials have large amount of impurities and lattice defects.

9. Examples: Carbon steel, Tungsten steel, Chromium steel, Cu‒Ni‒Fe (Cunife), Cu‒Ni‒Co (Cunico), Al‒Ni‒Co (Alnico)

10. Uses: It is used to make the permanent magnets which is used in magnetic detectors, microphones and magnetic separators.