Magnetic performance enhancement of Sn substitution MnBi rare-earth-free melt-spun ribbons

The effects of Sn dopant on microstructure and magnetic properties of MnBi 1 − x Sn x (x = 0; 0.05; 0.10; 0.15; 0.20; 0.25) melt-spun ribbons were systematically investigated. With increasing Sn content, the MnBi LTP fraction within the prepared ribbons exhibited a decreasing trend, associated with the formation of the Mn 3 Sn phase. The doped Sn atoms also affected the quenching process, altering the ribbons’ microstructures from the grain-like to rod-shaped. The optimized composition was found to be MnBi 0.95 Sn 0.05 , which was used to fabricate MnBi-based magnets. Maximum energy products of 12.9 MGOe, 8.1 MGOe, and coercivities of 14.8 kOe, 6.7 kOe were obtained in MnBi 0.95 Sn 0.05 melt-spun annealed ribbons and the magnets prepared from them, respectively.