Motion of Domain Walls in Ferromagnetic Steel Studied by TEM – Effect of Microstructural Features

Abstract

In a time-varying magnetic field, microstructural features inhibit the movements of the magnetic domain walls (DWs) in ferromagnetic materials. This leads to discontinuous changes in the magnetization generating a signal called Barkhausen noise (BN). A magnetic BN measurement is an important non-destructive testing (NDT) method in industry. In the varying magnetic field, a DW motion is hindered by microstructural features called pinning sites such as grain boundaries, voids, precipitates, and dislocations. To reveal the connection between microstructural features and BN, we studied and visualized the DW motion in ferromagnetic steel by TEM.