Magnetic properties and phase constitution of rapidly quenched nanocrystalline Gd-Fe-B alloys with various Gd contents

Abstract

To fully understand the performance of nanocrystalline ternary Gd-Fe-B alloys, an detailed investigation on the phase precipitation and magnetic properties of Gd10+xFe84-xB6 alloys (x = 0, 2–6) were carried out. The enhanced remanence Jr of 0.62 T and maximum energy product (BH)max of 37 kJ/m3 were obtained for Gd10Fe84B6 alloy. The coercivity significantly increased from 145 to 453 kA/m with the increase of Gd content from 10 to 16 at.% due to the formation of continuously distributed intergranular phase. Compared to many other RE-Fe-B alloys, Gd-Fe-B alloys show superior magnetic stability to withstand alternating temperature, demonstrated by lower irreversible loss. For the rapidly quenched amorphous Gd-Fe-B alloys, after annealing treatment, in addition to the Gd2Fe14B phase, the α-Fe, FexB, and GdFe2 phases also precipitated from the amorphous matrix for the alloys with x = 0, 2, and 4, respectively. Interestingly, the crystallized alloys annealed at optimum temperature exhibit similar hard magnetic properties as those of the optimized as-spun alloys, suggesting that the properties of Gd-Fe-B alloys are not sensitive to the process.