Investigation of magnetic and magnetomechanical hysteresis properties of Fe–Si alloys with classical and mechanical Barkhausen effects and magnetoacoustic emission

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Grain oriented Fe 3.5% Si sheet samples with a Goss (GO) microstructure and Fe 3.5% samples with nonoriented (NO) grains were tested using two Barkhausen effects, the classical Barkhausen effect (HBE) and the mechanical Barkhausen effect (MBE), as well as the magnetoacoustic emission (MAE). The aim of the work was to present further evidence that the B(H) hysteresis with effects like HBE and MAE, and magnetomechanical hysteresis with MBE are correlated via internal stress barriers pinning domain walls (DWs). In the case of a GO alloy, the long axis of the sample was parallel to the [100], [110], and [111] directions with respect to the rolling direction. The HBE and MAE were measured using a C-core electromagnet supplied with a triangular wave form of current intensity. The MBE intensity was recorded during a monotonous increase of shear stress using a torque machine. The maxima of MBE intensity for the “first load” mode for a NO sample and for three GO samples indicate an internal stress distribution pinning 90° DWs. The MAE plots reveal at least two maxima which are well correlated with H strength values where creation and annihilation of magnetic domains appears. Since the MBE and MAE are associated with abrupt jumps of 90° DW, the existence of MBE and MAE reinforces the fact that such DWs are present in the tested samples. These walls belong mainly to the secondary closure domains at GO alloys and to closure domains at NO alloy.