High damping in Fe-Ga-La alloys: Phenomenological model for magneto-mechanical hysteresis damping and experiment

Abstract

Ferromagnetic high damping (FHA) alloys with a wide temperature range from -150 °C to 300 °C have unique application value in extreme environments. In the present work, the damping behaviors of Fe-21Ga-xLa (x = 0.12 wt.%, 0.24 wt.%, 0.47 wt.%, 1.18 wt.%, and 2.33 wt.%La) alloys have been studied in detail, and a new phenomenological model has been proposed. With the increase of La content, the Laves phase (LaGa2) in the matrix increases gradually, and the resistance opposing the domain movement increases as well. Combined with the results of synchrotron radiation X-ray diffraction, neutron diffraction, and magnetic domain observation, the resistance mainly comes from three parts: the average stress related to the lattice distortion of the matrix, the average stress related to the increasing area energy of domain walls (DWs), and the average stress related to the increasing demagnetization energy induced by the Laves phase. Different from the traditional method of reducing internal stress through annealing to improve the damping capacity, the proper internal stress barriers are necessary to Barkhausen jumps to dissipate energy. Therefore, proper doping to balance resistance and mobility of DWs is a reliable way to improve damping capacity. Meanwhile, for Fe-Al and Fe-Cr based Alloys, the new model also has a good fitting effect. This study provides a theoretical and experimental reference for improving the functional properties of ferromagnetic alloys.