Crystallization behavior of Nd–Fe–B-based alloys

Abstract

Minor alloying additions to Nd–Fe–B significantly alter the crystallization kinetics of the alloy. The crystallization behavior of stoichiometric Nd 2Fe 14B displayed conventional behavior, with an Avrami exponent, n, close to 3. TiC additions stabilized the glassy phase and contributed to a more uniform crystallized grain structure. The time to complete crystallization was extended, implying a change in crystallization kinetics. The kinetic behavior and microstructural evolution implied growth-controlled crystallization. However, substitution additions to form a nine-component alloy displayed anomalous crystallization behavior (large n). EDS results, which showed partitioning of Ti and C, interfacial enrichment of the rare-earth elements, and interfacial depletion of Fe, suggested that diffusion processes may be important in this system, while microstructural development suggested that the transformation was dominated by a rapidly changing nucleation rate.