Preparation and magnetic properties of MnBi alloy and MnBi /Fe hybrid magnets

Abstract MnBi alloys were prepared using arc melting with different atomic proportions between Mn and Bi and then heated at 573 K for 30 h. MnBi /Fe hybrid magnets were also prepared by modulating MnBi content. The microstructure evolution, the content of ferromagnetic low temperature phase MnBi, and the magnetic properties of MnBi alloys and MnBi /Fe hybrid magnets were studied systematically. Results showed that the composition and heat treatment had obvious influences on the saturation magnetization of MnBi alloy, where the saturation magnetization increased quickly following the heat treatment. The saturation magnetization initially increased and then decreased with increasing the content of Mn, which was consistent with the change of mass percentage of the LTP MnBi. The MnBi alloy with 50 at% Mn exhibited maximum magnetization as 62.0 emu/g with 30 KOe applied field at 300 K. The ratio of the content between Fe and MnBi had a remarkable effect on the magnetic performance. The saturation magnetization of MnBi/Fe hybrid magnets increased obviously with increasing the content of Fe. Meanwhile, the coercivity of the composite magnet increased dramatically with increasing the content of MnBi