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MnBi forms peritectically at ∼450 °C. Preparation of MnBi employing conventional techniques such as arc melting and induction melting results in the segregation of manganese. In order to avoid this segregation, we followed the procedure recommended by Guo et al. [X. Guo, A. Zaluska, Z. Altounian, and J. O. Strom-Olsen, J. Mater. Res. 5, 2646 (1990)] and prepared a low-temperature phase of MnBi by melt spinning, followed by heat treatment. Fine powder of MnBi was prepared by ball milling the melt-spun ribbons for various lengths of time. Magnetic properties of these powders were determined. In particular, the temperature dependent coercivity was studied from room temperature to 360 °C for the powders ball milled for 2 and 10 h. The coercivity is found to increase with the increase in temperature reaching a maximum of 25.8 kOe at 280 °C and then decrease as the temperature is increased further. We also found that a peak in coercivity is observed for the samples milled for 10 h. MnBi shows a first-order transition to a paramagnetic phase at 360 °C. In an attempt to increase this transition temperature, an alloy of composition Mn0.75Ni0.25Bi0.5Sb0.5 was made by induction melting. The transition temperature increases from 360 °C for MnBi to 400 °C for Mn0.75Ni0.25Bi0.5Sb0.5.