Nd–Fe–B-based anisotropic nanocrystalline hard magnetic alloys

Abstract

Nd 10.5 Fe 83.5−x Ga x B 6 (x=1.5, 3 and 4.5) ribbons were prepared by melt-spinning method with various wheel speeds from 5 to 40 m s −1. Strong crystallographic texture with c-axis of Nd 2 Fe 14 B crystallites along normal of the ribbon surface was observed. The texture degree can be enhanced by decreasing the quenching rate during solidification of the melt and by increasing the concentration of Ga. Preferred orientation of the nanocrystallites with their size of 10–30 nm is obtained not only by controlling the quenching rate of the melt during solidification but also by appropriately annealing the over-quenched ribbons. The texture of microstructure clearly affects magnetic anisotropy of the ribbons. With increasing concentration of Ga, the magnetic anisotropy of the ribbons is considerably increased. The coercivity above 6.5 kOe and maximum energy products larger than 15 MGOe can be achieved on the ribbons with Ga-concentration of 1.5%.

Phase Formation and Magnetic Properties of Melt Spun and Annealed Nd-Fe-B Based Alloys with Ga Additions

“…Another important question linked to the formation of a highly coercive state is the alloying of the Nd-Fe-B system. For the last 30 years or more of the investigation of the Nd 2 Fe 14 B compound, the influence of a large number of alloying components has been studied, but the most interesting effect can be observed with Ga addition [13][14][15][16][17]. The influence of Ga on the formation of the texture during the quenching process from the liquid state was studied by Nguyen et al [13].…”

“…For the last 30 years or more of the investigation of the Nd 2 Fe 14 B compound, the influence of a large number of alloying components has been studied, but the most interesting effect can be observed with Ga addition [13][14][15][16][17]. The influence of Ga on the formation of the texture during the quenching process from the liquid state was studied by Nguyen et al [13]. Since the main drawback of materials obtained by the extreme effects methods is the isotropy of their properties, the formation of the texture could greatly increase (BH) max and surpass the sintered magnets in terms of properties.…”