Microstructure and magnetic properties of (Pr,Tb)2(Fe,Nb,Zr)14B/α-Fe nanocomposites

Abstract

The microstructure and magnetic properties of Pr2Fe14B/α-Fe nanocomposites with small amount of Tb, Nb, and Zr additions have been investigated. A c-axis texture in the 2:14:1 phase has been observed in ribbons spun at speeds below 14 m/s. Optimal magnetic properties were found in annealed samples spun at 14–17 m/s. With small additions of Nb and Zr, the coercivity significantly increases. Nb substitution leads to a poor loop squareness, which can be significantly improved with Zr addition due to a refinement in microstructure, resulting in a drastic increase in the energy product. Optimum magnetic properties with a room temperature coercivity of 8.2 kOe, and (BH)m=20.3 MGOe have been obtained in Pr7Tb1Fe87Nb0.5Zr0.5B4 ribbons. Transmission electron microscopy on this sample revealed a much finer and homogeneous microstructure with an average grain size of 20 nm.

Hard magnetic properties in Pr2Fe14B/α-Fe nanocomposite magnets with a combined addition of V and C

“…But the value of room-temperature optimum energy product (BH) max obtained in experiment is about 20 MGOe for nanocomposite melt-spun ribbons [6][7][8][9], much lower than the theoretical calculations. In the previous studies, the nanocomposite Fe 3 B/R 2 Fe 14 B system containing less rare-earth elements (3.5-4.5 at%) and higher B content (18-20 at%) has an enhancement in remanence due to the exchange-coupling effect between two kinds of phases and exhibits a very high remanence ratio ranging from 0.7 to 0.8 [3,4,10], but a low coercivity less than 5 kOe.…”

“…Microalloying prepared by adding one or two elements with an appropriate quantity into master alloys has been shown to effectively refine the microstructure [20,21], although the saturation magnetization J s and remanence B r decrease simultaneously due to the magnetic dilute effect. Based on the above, the best magnetic properties of nanocomposite magnet with a master alloy composition R [8][9] Fe 87-86 B 5-6 may be achieved by microalloying through balancing the remanence and the coercivity of the magnet.…”

Enhancement of the maximum energy product of α-Fe∕Nd2Fe14B nanocomposite magnets by interfacial modification

“…To improve the interfacial structure, in the present study, we produce an interfacial amorphous phase with a volume fraction of 14%-16% in ␣-Fe/ Nd 2 Fe 14 B nanocomposites by a proper addition of Nb in the melt-spun NdPrFeCoB. 4,[7][8][9] Recently, positron annihilation studies show that 10,11 the dominating interfacial structure in nanocomposite magnets has a loosely packed atomic structure with vacancy-sized free volumes, which will weaken the magnetic exchange coupling between the soft-and hard-magnetic grains 12 and reduce the anisotropy constant near grain surfaces, 13 and thus lead to a low energy product for the magnets. 2 Nanocomposite exchange coupled magnets consisting of a fine mixture of hard-and soft-magnetic phases 1 have attracted much attention for the development of permanent magnets since a high maximum energy product above 50 MG Oe would be expected in the magnets.…”

Study on Magnetic Behavior of Nd8Fe84Ti2B6 Nanocomposite by FORC Diagram

“…Hence, the microstructure plays a key role in determining the magnetic behavior. Uniform phase distribution in combination with fine grain sizes is needed for excellent magnetic performance in Nd 2 Fe 14 B /α-Fe composite 4 . Melt spinning method is an effective way to produce Nd 2 Fe 14 B/α-Fe nanocomposite.…”