The effect of the addition of M element (M=Zr, Nb, V, Si and Ga) on the microstructural and magnetic properties of nanocomposite alpha-Fe/Nd_2Fe_(14)B and Fe_3B/Nd_2Fe_(14)B magnets

摘要

Two types of nanocomposite permanent magnets, i.e., a-Fe/Nd_2Fe_(14)B and Fe_3B/Nd_2Fe_(14)B, have been extensively studied to achieve high coercivity and high maximum energy product. The magnetic properties of these nanocomposite magnets strongly depend on the exchange-coupling between the hard magnetic phase (Nd_2Fe_(14)B) and the soft magnetic phase (alpha-Fe or Fe_3B), which is closely related to the microstructure. Both the micromagnetic modeling work and experimental studies have shown that the coercivity and maximum energy product can be increased by refining the microstructure of the constituent phases, which can be achieved by adding a small amount of transition metals and metalloids. However, some other studies revealed that the change in the coercivity could not be related to the change in the grain size, suggesting that some other factor controls the magnetic properties. In this paper, we present our work on the effects of the addition of Zn Nb, V; Si and Ga to both the a-Fe/Nd_2Fe_(14)B and Fe_3B/Nd_2Fe_(14)B nanocomposites on the microstructure and magnetic properties using atom probe field ion microscopy (APFIM), transmission electron microscopy (TEM), and vibrating sample magnetometry.