Explain Soft magnetic materials.

Soft magnetic materials -They contain small enclosed area of hysteresis loop, high permeability low eddy current losses and high saturation value that is achieved using laminated cores and less residual magnetism. Soft magnetic materials keep their magnetism as long as they are energised through an external magnetic field; illustration: Alpha iron, silicon ferrite and super permalloy (Ni-Fe-Mo). Soft magnetic materials are utilized for the construction of cores for transformers, electrical machines, cores of audio frequency couplings and electromagnets reactors and matching transformers in telecommunication.

Hard Magnetic materials-have a slowly rising magnetization curve along with large hysteresis loop area and therefore large energy losses. They contain high value of coercivity, high value of retentivity and low permeability. For saturating the hard magnetic materials, a high magnetizing force is needed. Hard magnetic materials have the property of retaining their magnetism still after the magnetising field is eliminated. Illustration: Alnico (Al-Ni-Co), retaining similar and Cobalt steel for a long time. Because of this property they are utilized in manufacture of permanent magnets.

B-H curves for soft and hard magnetic materials