Using the Barkhausen Effect to Measure the Microstructure of Ferromagnetic Materials

Speaker:
Nolting, Volkmar; Vaal University of Technology; South Africa

Authors:
Nolting, V.; Vaal University of Technology; South Africa
Mabuza, B.R.; Vaal University of Technology; South Africa

ID: ECNDT-0387-2018
Download: PDF
Session: Magnetic Methods - Barkhausen 2
Room: R2
Date: 2018-06-11
Time: 15:40 - 16:00

The paper seeks to illustrate the usefulness of the Barkhausen effect in measuring the microstructure of ferromagnetic materials. The magnetization of a ferromagnetic materials, as determined from standard models of magnetism, makes a couple of theoretical assumptions that are not fulfilled in a real lattice. One consequence of this is the Barkhausen effect which experimentally verifies the existence of ferromagnetic domains. Barkhausen noise is strongly related to strain at grain boundaries confirming the dependence of magnetoacoustic emission on magnetostriction.

From the energy of the domain wall, its thickness, the energy per unit area, the restoring force and the coercitivity are determined and compared with experimental data. Magnetization curves are plotted along both the hard and easy axis of a ferromagnetic solid. The magnetic anisotropy effect is discussed in this paper.
This observation turns out to be useful in applications to Nondestructive evaluation to monitor microstructural features and defects in the material. The magnetoacoustic emission signal can detect flaws even in the bulk of the material while Barkhausen emission measurements are limited to surface defects only. The findings are presented and discussed.