Influence of the dislocation structures on the magnetic and magnetomechanical properties of high-purity iron

The influence of dislocation structures on the motion of magnetic domain walls (DW) was investigated in high-purity polycrystalline iron by measuring the magnetomechanical damping and the magnetic properties (coercive field and parameters of the Rayleigh law). The dislocation structures created by strain-hardening were observed by high-voltage (800 kV), transmission electron microscopy (TEM). As the flow stress increases from 25 to 128 N.mm-2, the four quantities under study exhibit three successive stages related to different dislocation distributions. They reflect different weighted averages of the DW interactions with isolated dislocations (stage I), dislocation tangles (stage II), and dislocation cells (stage III).