Enhanced magnetic properties in Zr-containing rare earth-rich Didymium (Nd/Pr)-based nanocrystalline hard magnetic alloys

Abstract

A systematic study of the influence of processing conditions and Zr addition on the magnetic properties of RE-rich, Didymium (Nd/Pr) 14Fe 80B 6 (Nd:Pr ratio of 3:1) is reported. For directly quenched alloys, various roll speeds resulted in grain sizes d g within the range 35–50 nm. Increasing remanence J r and maximum energy product (BH) max values were observed as d g decreased (up to 0.86 T and up to 124 kJ/m 3, respectively). Small Zr addition (1 at.%) resulted in improved J r and (BH) max (up to 0.92 T and up to 142 kJ/m 3, respectively). For overquenched and annealed alloys, partial substitution of Fe by Zr (0–4 at.%) indicated a marked dependence of the magnetic properties on Zr content, with an excellent combination of J r, (1.0 T), i H c (1574 kA/m) and (BH) max (149 kJ/m 3) at 2 at.% Zr. Results are interpreted in terms of variations in the scale of the nanostructure and of the effects of Zr substitutions into the 2/14/1 unit cell.