The influence of microstructure on magnetic properties of nanocrystalline Fe–Pt–Nb–B permanent magnet ribbons

Abstract

A FePt-based hard-magnetic nanocomposite of exchange spring type was prepared by isothermal annealing of melt-spun Fe52Pt28Nb2B18 (atomic percent) ribbons. The relationship between microstructure and magnetic properties was investigated by qualitative and quantitative structural analysis based on the x-ray diffraction, transmission electron microscopy, and F57e Mössbauer spectrometry on one hand and the superconducting quantum interference device magnetometry on the other hand. The microstructure consists of L10-FePt hard-magnetic grains (15–45 nm in diameter) dispersed in a soft magnetic medium composed by A1 FePt, Fe2B, and boron-rich (FeB)PtNb remainder phase. The ribbons annealed at 700 °C for 1 h exhibit promising hard-magnetic properties at room temperature: Mr/Ms=0.69; Hc=820 kA/m and (BH)max=70 kJ/m3. Strong exchange coupling between hard and soft magnetic phases was demonstrated by a smooth demagnetizing curve and positive δM-peak in the Henkel plot. The magnetic properties measured from 5 to 750 K reveals that the hard characteristics remains rather stable up to 550 K, indicating a good prospect for the use of these permanent magnets in a wide temperature range.

Impact of Antisymmetric Anisotropy on Magnetisation of Ultra-Hard Nanocrystalline Alloys

“…New and continuously increasing requirements can be fulfilled by modern nanostructured magnetic composites containing different phases characterized by different magnetic properties. In the field of hard magnets, interactions between the phases are especially important and can lead to an appearing of new and unique properties [1,2]. Recently, we reported ultrahigh coercivity (about 3.6 T) in Fe-Nb-B-Tb type of bulk nanocrystalline alloys prepared by vacuum suction casting technique [3].…”

Influence of Cooling Rate on Magnetic Properties of (Fe_{80}Nb_{6}B_{14})_{1-x}Tb_{x} Type of Bulk Nanocrystalline Alloys

“…Among well known permanent magnets, such as CoSm, Fe-Pt or Fe-B-Tb types of alloys and compounds [1,2], the Fe-Nb-B-Tb alloy family plays an important role [3]. Recently we have reported that the (Fe 80 Nb 6 B 14 ) 1−x Tb x bulk nanocrystalline series of alloys can be considered as high coercive materials [4].…”

Magnetic Properties of the Rapidly Solidified Bulk Alloy: Fe61Co10B20Y8-xWyPtx (where: x=1,2; y=0,1)

“…In recent years, intensive research has been conducted into Pt-based alloys [2,5,6,7]. In most scientific studies, the Pt additive comprises more than 5% of the investigated material, which leads to significant magnetic hardening of the described alloys; also, most of these studies were conducted on rapidly-cooled tape or ribbon samples [2,5,6,7]. A two-phase magnetic structure in Pt-tapes can be obtained as a result of thermal treatment [5,7].…”