An overstoichiometric Nd–Fe–B hard magnetic material

A commercial Nd-rich Nd–Fe–B-based hard magnetic material was studied. The obtained results were compared before and after recording of the thermomagnetic curve up to 800 °C. The curve itself showed clearly besides Curie points of the Nd2Fe14B phase and α-Fe also another critical temperature. Mössbauer spectroscopic (MS) phase analysis and X-ray diffraction analysis (XRD) showed in addition to the commonly known phases Nd2Fe14B and NdFe4B4 also some paramagnetic and ferromagnetic iron atoms (MS) and Fe17Nd2 intermetallics (XRD). During the exerted thermal treatment, the content of the Nd2Fe14B and NdFe4B4 phases remained almost unchanged, while iron atoms from remnant minor phases built a separate α-Fe phase. The XRD pattern also showed the presence of some minor Nd phase. The results of Squid magnetic measurements suggest a nanocrystalline decoupled structure of the Nd-rich alloy in the optimized magnetic state. Measurement of the magnetization loop showed, in spite of small changes in the phase composition, that magnetic properties of the quality material deteriorated during the thermal treatment

Polymer-Bonded Magnetic Materials with Various Nd-Fe-B Filler Content

One of the more important developments in magnetic materials, polymer bonded magnets, have opened a new world of application opportunities. The Nd-Fe-B/polymer composite materials offer an excellent combination of strong magnetic and dynamical-mechanical properties. However, the transition temperatures of filler and matrix should be selected carefully considering the future application. Uniform particle distribution and good adhesion between Nd-Fe-B powder particles and polymer are essential for the quality of the composite, while stiffness of polymer matrix is one of the influencing factors as well. The damping properties of Nd-Fe-B/polymer composites with 15 wt.%, 50 wt.% and 75 wt.% of Nd-Fe-B powder were studied by dynamic mechanical analysis and compared with a pure polymer sample. Thermal stability was analyzed using a simultaneous differential scanning calorimetric and thermogravimetric analysis technique.11th Annual Conference of the Materials-Research-Society-of-Serbia (YUCOMAT 2009), Aug 31-Sep 04, 2009, Herceg Novi, Montenegr

Electrodeposition of Co-Ni-MoxOy Powders: Part I. The Influence of Deposition Conditions on Powder Composition and Morphology

The Co-Ni-MoxOy powders were obtained electrochemically at a constant current density from ammonia electrolyte. Ni and Co were anomalously deposited, inducing Mo deposition, which cannot be deposited separately from aqueous solutions. The obtained Co-Ni-MoxOy powders were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electon microscope (SEM) methods. Based on the obtained experimental results, it was concluded that the particle size of deposited powders is influenced by the chemical composition of the electrolyte and current density imposed. XRD results suggested that obtained powders were of amorphous structure, although a Co3Mo compound can be formed if certain experimental conditions are applied

Phase composition and magnetic properties of multiphase melt-spun Nd4.3Fe76.2B19.5 alloy

Phase transformations and magnetic properties of multiphase Nd4.3Fe76.2B19.5 alloy were investigated in the temperature range of heat treatment 600-700 degrees C. The influence of different heat treatment regimes was observed by correlation of phase composition and measured magnetic properties. The heat treatment regime, which provided the microstructure that improves exchange interactions between grains of soft and hard magnetic phases and consequently enhances magnetic properties, was defined and discussed. For optimized magnetic alloy grain size of the present phases Fe3B, Nd2Fe14B and alpha-Fe was calculated by size-strain analysis of X-ray powder diffraction data. Calculated mean grain size was on a nanoscale, below 30 nm.Research Trends in Contemporary Materials Science, 8th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 04-08, 2006, Herceg Novi, Montenegr

The comparative study of Nd-Fe-B magnetic materials with different Nd content

For the purpose of better understanding of the effect of different Nd content on the magnetic properties of three types of commercial Nd-Fe-B alloys with 10-12 wt% Nd (Nd-low), 21-25 wt% (Nd-stoich.), and 26-29 wt% Nd (Nd-rich) were simultaneously analyzed using X-Ray and Fe-57 Mossbauer spectroscopy analysis. The observation was based on correlation of starting chemical composition with phase composition and magnetic properties of the alloys in optimized magnetic state

The comparative study of Nd-Fe-B magnetic materials with different Nd content

For the purpose of better understanding of the effect of different Nd content on the magnetic properties of three types of commercial Nd-Fe-B alloys with 10-12 wt% Nd (Nd-low), 21-25 wt% (Nd-stoich.), and 26-29 wt% Nd (Nd-rich) were simultaneously analyzed using X-Ray and Fe-57 Mossbauer spectroscopy analysis. The observation was based on correlation of starting chemical composition with phase composition and magnetic properties of the alloys in optimized magnetic state

The comparative study of Nd-Fe-B magnetic materials with different Nd content

For the purpose of better understanding of the effect of different Nd content on the magnetic properties of three types of commercial Nd-Fe-B alloys with 10-12 wt% Nd (Nd-low), 21-25 wt% (Nd-stoich.), and 26-29 wt% Nd (Nd-rich) were simultaneously analyzed using X-Ray and Fe-57 Mossbauer spectroscopy analysis. The observation was based on correlation of starting chemical composition with phase composition and magnetic properties of the alloys in optimized magnetic state