Magnetic property enhancement of rare-earth-free nanocrystalline LTP-MnBi melt-spun ribbons

Rare-earth-free low-temperature-phase MnBi alloys have attracted extensive attention, but achieving high-purity and high-performance remains a challenge. In this study, a low-temperature phase (LTP) MnBi alloy was prepared through melt spinning and vacuum annealing techniques. The crystalline structure, microstructure, and magnetic properties of MnBi alloys were systematically investigated by x-ray diffraction, scanning electron microscopy, and physical property measurement system. Results showed that roller speed effectively improved the purity and coercivity of MnBi alloys. The optimization of process parameters achieved a high saturation magnetization of 70.7 A m2/kg and a significant coercivity of 2.34 T (at 450 K). It revealed that microstructure and magnetic properties were closely associated with rolling speed processes. This work serves as an exemplar for the fabrication of high-performance LTP-MnBi alloys, exhibiting its potential for high-temperature applications.