Effect of Fe doping on the magnetic properties of MnBi alloy

Structure and magnetic properties of Fe-doped MnBi alloy with a range of Fe concentrations were systematically investigated. The coercive field and saturation magnetization (M-s) were drastically changed according to the fabrication methods and Fe contents. The addition of Fe element could enhance the coercivity (H-c) of the MnBi-based alloy, and the increased H-c of 1.76 T was reached in the Mn55Bi45-Fe (15 wt%) ball-milled ribbon. Moreover, a high remanence ratio (M-r/M-s) of 97.0% was achieved in the Mn55Bi45-Fe (7.5 wt%) ball-milled ingot. In addition, as the concentration of Fe increases from 0 to 15 wt%, the Curie temperature (T-c) was increased from 635 to 652 K. This demonstrates that Fe-doped MnBi rare-earth permanent magnets could be a promising candidate for high-temperature applications. The relationship between magnetic properties and intermetallic lattice variations were discussed with precise Rietveld refinement analysis. (C) 2020 Elsevier B.V. All rights reserved.