Fundamental properties of melt-spun stoichiometric Y2Fe14B alloy and the advantages of Nd substitution

Abstract

Here we investigate the effects of wheel speed and heat treatment on the melt-spun ternary Y2Fe14B alloy, aiming to clarify its structure, phase precipitation and magnetic properties. For directly quenched alloys, the optimum magnetic properties can be achieved when the wheel speed is within a relatively wide range of 30–40 m/s. The Y2Fe14B alloy prepared at 36 m/s shows the highest coercivity of 149 kA/m and remanence of 0.88 T with the maximum energy product (BH)max of 6.8 MGOe due to the single hard magnetic phase structure. For the amorphous ribbons prepared at 50 m/s, when the annealing temperature increases from 773 to 1073 K, the α-Fe phase precipitates first accompanied by the appearance of Y2Fe14B phase and a small quantity of Fe-B phase. The magnetic properties of annealed samples are much lower than those of the optimized as-spun alloys. The effects of Nd substitution for Y on the structure, magnetic properties and thermal stability of (Y1-xNdx)2Fe14B (x = 0–1) alloys have been systematically investigated. The Hcj and (BH)max exhibit almost linear increase with the increasing Nd substitution. Relatively low temperature coefficients can be obtained in the Nd substituted alloys. The current results are important for exploring high performance and low cost Y­based rare earth permanent magnets with improved thermal stability.