The influence of grain size and impurities on the magnetic properties of the soft magnetic alloy 47.5% NiFe

An attempt has been made to equate quantitatively the coercive force as a function of the grain size and the concentration of nonmagnetic inclusions. It was found that the coercive force Hcof recrystallized 47.5% nickel-iron can be completely described, independent of the final anneal temperature, by the grain size dKand the inclusion content NF. Only nonmagnetic inclusions of sub-micron size (0.02- 0.5 μm) were found to be of significance. A definite correlation between the coercive force of 47.5% nickel-iron and those inclusions visible using an optical microscope (> 1μm) was not observed. Furthermore, there was no clear dependence of the coercive force on the sulfur and oxygen content. The grain size term HcKwas found to be in good agreement with the theory of A. Mager [1]. Surprisingly, there was no difference between the low-angle grain boundaries of strip with cube texture and the large-angle grain boundaries of un-textured strip with respect to HcK.