Hydrogen disproportionation phase diagram and magnetic properties for Nd15Fe79B6 alloy
来源期刊：JOURNAL OF RARE EARTHS2016年第8期
论文作者：Mateusz Szymański Bartosz Michalski El?bieta Jezierska Marcin Leonowicz
文章页码：843 - 849
摘 要：Transformation-temperature-hydrogen pressure phase diagram was constructed for a Nd15Fe79B6 alloy in order to estimate appropriate conditions for hydrogenation, disproportionation, desorption and recombination reaction（the HDDR）. Optimised recombination time（the highest coercivity） was found to be 10 min. for 5 g samples processed at 740 oC. Several HDDR processes were carried out at 30 kP a of hydrogen pressure at various temperatures. No correlation between magnetic propertiec and a direction of measurement was observed for the samples processed at 740 oC. Remanence anisotropy was induced along an alignment direction when the temperature of the HDDR process was increased up to 800 oC and 850 oC for <100 μm and 100–160 μm particles, respectively. Simultaneously, a small drop in coercivity was observed in the direction of alignment for <100 μm particles, but no for 100–160 μm particles. Furthermore, probably an ordered phase was found by TEM microstructure analysis in the bulk sample disproportionated at 850 oC under 150 kP a of hydrogen. Grains with antiphase domains were observed and corresponding electron diffraction patterns were resolved, likely indicating superlattice structures.
Mateusz Szymański1，Bartosz Michalski1，El?bieta Jezierska1，Marcin Leonowicz1
1. Faculty of Materials Science and Engineering, Warsaw University of Technology
摘 要：Transformation-temperature-hydrogen pressure phase diagram was constructed for a Nd15Fe79B6 alloy in order to estimate appropriate conditions for hydrogenation, disproportionation, desorption and recombination reaction（the HDDR）. Optimised recombination time（the highest coercivity） was found to be 10 min. for 5 g samples processed at 740 oC. Several HDDR processes were carried out at 30 kP a of hydrogen pressure at various temperatures. No correlation between magnetic propertiec and a direction of measurement was observed for the samples processed at 740 oC. Remanence anisotropy was induced along an alignment direction when the temperature of the HDDR process was increased up to 800 oC and 850 oC for <100 μm and 100–160 μm particles, respectively. Simultaneously, a small drop in coercivity was observed in the direction of alignment for <100 μm particles, but no for 100–160 μm particles. Furthermore, probably an ordered phase was found by TEM microstructure analysis in the bulk sample disproportionated at 850 oC under 150 kP a of hydrogen. Grains with antiphase domains were observed and corresponding electron diffraction patterns were resolved, likely indicating superlattice structures.
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