Magnetic BiMn-α phase synthesis prediction: First-principles calculation, thermodynamic modeling and nonequilibrium chemical partitioning

[Display omitted] •First-principles calculations with Hubbard U correction and SQSs were employed.•Gibbs free energy function of individual phases was evaluated.•The magnetic field-T−x(Mn) dependent phase selections were predicted.•Single- or multiple-phase microstructure can be controlled by chemical partitioning.•The magnetic properties can be tailored by controlling the microstructures. BiMn-α is promising permanent magnet. Due to its peritectic formation feature, there is a synthetic challenge to produce single BiMn-α phase. The objective of this study is to assess driving force for crystalline phase pathways under far-from-equilibrium conditions. First-principles calculations with Hubbard U correction are performed to provide a robust description of the thermodynamic behavior. The energetics associated with various degrees of the chemical partitioning are quantified to predict temperature, magnetic field, and time dependence of the phase selection. By assessing the phase transformation under the influence of the chemical partitioning, temperatures, and cooling rate from our calculations, we suggest that it is possible to synthesize the magnetic BiMn-α compound in a congruent manner by rapid solidification. The external magnetic field enhances the stability of the BiMn-α phase. The compositions of the initial compounds from these highly driven liquids can be far from equilibrium.