Effects of the substitution of B for P on structure and magnetic properties of FePB amorphous alloys are investigated by first-principle molecular dynamics. Our analysis shows that Fe-centered polyhedra are mainly distorted icosahedral structures, and P- or B-centered polyhedra are mainly icosahedrons and triangular prisms. It is found that Fe₈₀P₅B₁₅ amorphous alloy has the most 15xx bond pairs and higher local five-fold symmetry. With the increase of B atoms, magnetic moment of the amorphous alloy gradually increases, which is in good agreement with the experiments. Due to higher local symmetry, Fe₈₀P₅B₁₅ amorphous alloy produces a larger splitting exchange energy and hence a higher magnetic moment. Fe atoms are easy to lose electrons to be positively charged, but B or P atoms are easily to gain electrons and are negatively charged. In addition, on account of the small radius of B atoms, more Fe atoms are aggregated locally in Fe₈₀P₅B₁₅ amorphous alloy. The more the number of neighboring Fe atoms, the largrer the magnetic moment of Fe atoms is, which makes magnetic moment in amorphous alloys gradually increases. These findings provide intentional guidance for the development of new soft magnetic materials.

采用第一性原理分子动力学研究了B代替P对FePB非晶合金结构和磁性能的影响。我们的分析表明，以Fe为中心的多面体主要是扭曲的二十面体结构，而以P或B为中心的多面体主要是二十面体和三棱柱。发现Fe ₈₀ P ₅ B ₁₅非晶合金具有最多的15xx键对和较高的局部五重对称性。随着B原子的增加，非晶合金的磁矩逐渐增大，与实验结果吻合较好。由于较高的局部对称性，Fe ₈₀ P ₅ B ₁₅非晶合金产生较大的分裂交换能，因此产生较高的磁矩。Fe原子易失电子带正电，而B或P原子易得电子带负电。此外，由于B原子半径小，Fe ₈₀ P ₅ B ₁₅非晶合金中局部聚集的Fe原子较多。相邻Fe原子的数量越多，Fe原子的磁矩越大，这使得非晶合金中的磁矩逐渐增大。这些发现为新型软磁材料的开发提供了有意的指导。