Hydrogen disproportionation phase diagram and magnetic properties for Nd15Fe79B6 alloy

Mateusz Szymański , Bartosz Michalski , Elżbieta Jezierska , Marcin Leonowicz , Zbigniew Miazga

Abstract

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 °C. Several HDDR processes were carried out at 30 kPa of hydrogen pressure at various temperatures. No correlation between magnetic propertiec and a direction of measurement was observed for the samples processed at 740 °C. Remanence anisotropy was induced along an alignment direction when the temperature of the HDDR process was increased up to 800 °C and 850 °C 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 °C under 150 kPa of hydrogen. Grains with antiphase domains were observed and corresponding electron diffraction patterns were resolved, likely indicating superlattice structures.

Author Mateusz Szymański (FMSE / DCFM)
Mateusz Szymański,,
- Division of Construction and Functional Materials
, Bartosz Michalski (FMSE / DCFM)
Bartosz Michalski,,
- Division of Construction and Functional Materials
, Elżbieta Jezierska (FMSE / DCFM)
Elżbieta Jezierska,,
- Division of Construction and Functional Materials
, Marcin Leonowicz (FMSE / DCFM)
Marcin Leonowicz,,
- Division of Construction and Functional Materials
, Zbigniew Miazga - PPHU Polblume [P.P.H.U. Polblume Zbigniew Miazga]
Zbigniew Miazga,,
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Journal seriesJournal of Rare Earths, ISSN 1002-0721
Issue year2016
Vol34
Pages843-849
Publication size in sheets0.5
ASJC Classification1600 General Chemistry; 1906 Geochemistry and Petrology
DOIDOI:10.1016/S1002-0721(16)60104-7
Languageen angielski
Score (nominal)25
Score sourcejournalList
ScoreMinisterial score = 25.0, 10-06-2020, ArticleFromJournal
Ministerial score (2013-2016) = 25.0, 10-06-2020, ArticleFromJournal
Publication indicators Scopus Citations = 2; Scopus SNIP (Source Normalised Impact per Paper): 2016 = 1.122; WoS Impact Factor: 2016 = 2.429 (2) - 2016=1.898 (5)
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