Production of Nd–Fe–B alloys by the glass slag method

Abstract

The microstructures of the Nd–Fe–B alloy with the stoichiometric composition of ${\mathrm{Nd}}_2{\mathrm{Fe}}_{\mathrm{14}}\mathrm{B}$ produced by the glass slag method were investigated. The Nd–Fe–B melts in the molten slag materials such as lead silicate glass, soda-lime glass, and Pyrex glass experienced a large undercooling over 160 K below solidification. When the Nd–Fe–B melts were solidified either in the molten lead silicate glass or in the molten soda-lime glass, the resultant Nd–Fe–B alloys had coarse dendrites of α-Fe phase together with grains of ${\mathrm{Nd}}_2{\mathrm{F}}_{14}\mathrm{B}.$ On the other hand, the Nd–Fe–B alloys exhibited columnar dendrite grains of ${\mathrm{Nd}}_2{\mathrm{Fe}}_{14}\mathrm{B}$ phase when the Nd–Fe–B melts were solidified in the molten Pyrex glass.