Permeability and Hysteresis Loop Measurements of Amorphous and Annealed Samples of Fe73.5-xCrxCu1Nb3Si13.5B9 Alloys

Permeability and coercivity are the most important parameters for the evaluation of soft magnetic materials. The criteria for the softest magnetic materials demand very high permeability and / or extremely low coercivity and these properties necessitate the anisotropy energy and the magnetoelastic energy tend towards zero. These unique demands are fulfilled when the FINEMET type of nanocrystalline materials are thermally treated around there primary crystallization temperature which facilitates the evolution of nanometric size of the Fe(Si) grains (10-12 nm) that are exchanged couple through the remaining thin residual amorphous interface. In order to correlate the microstructural features with soft magnetic properties of the alloys and initial permeability of the toroidal shaped samples annealed at different temperatures are measured at room temperature with an applied ac field of 10 Oe. Magnetic hysteresis is a useful attribute of permanent magnetic material in which we wish to store a large metastable magnetization. On the other hand, a large class of applications requires small hysteresis losses per cycle. These include applications as inductors, low and high frequency transformers, alternating current machines, motors, generators and magnetic amplifiers. Present paper focuses on the measurement of permeability and hysteresis loops of samples both their amorphous and nanocrystalline states.