Internal Demagnetizing Factor in Ferrous Metals

Jenő Takács,György Kovács,Lajos K Varga

doi:10.1155/2012/752871

Jenő Takács, György Kovács + Show 1 more

Open Access

https://doi.org/10.1155/2012/752871

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Abstract

Modelling the saturation major loop of a ferrous metal produces the intrinsic magnetization parameters; fitting the measured commutation curve, however, can yield different results. The relation of the intrinsic loci of the vertices of the minor loops (ND=0) to the experimental curve (ND≠0) is investigated. The two-way transformation between the two curves is formulated in closed mathematical form with the help of the internal demagnetization factor, ND. The method is applied to four ferrous metals, with widely different intrinsic properties (soft nonoriented Fe-Si steel, normalized low carbon steel, and Finemet in nanocrystalline and amorphous state) supporting the predictions of the proposal. The developed relationship is model independent and it is shown that the ND factor depends linearly on coercivity based on experimental evidence.

Highlights

A large number of the measurements of ferrous substances are aimed at finding the intrinsic material properties [1] of the tested ferrous sample
The saturated major hysteresis loop of the sample carries all the intrinsic magnetic parameters directly recoverable from the measured data. Within this loop lie the unhysteretic loci of the vertices of the symmetrical minor loops, the only curve, which belongs to both the ascending and descending branches of the hysteresis loops [5, 6]
The method was subjected to tests on four magnetic materials with widely ranging magnetic properties

Summary

Introduction

A large number of the measurements of ferrous substances are aimed at finding the intrinsic material properties [1] of the tested ferrous sample (as defined by Fiorillo). The most commonly accepted way is to make the sample turn into a closed magnetic circuit, such as a toroid or an Epstein square [1,2,3] These two methods are not completely free from the ever-present internal demagnetization, they suffer the least from it [1]. The saturated major hysteresis loop of the sample carries all the intrinsic magnetic parameters directly recoverable from the measured data Within this loop lie the unhysteretic loci of the vertices of the symmetrical minor loops, the only curve, which belongs to both the ascending and descending branches of the hysteresis loops [5, 6].

The Intrinsic Loci of Vertices

The Effective Field and Its Implications

Experimental Verification

Nd as a Function of Coercivity

Conclusions