Hydrogen disproportionation phase diagram and magnetic properties for Nd15Fe79B6 alloy

作者：Szymanski Mateusz^*; Michalski Bartosz; Jezierska Elzbieta; Leonowicz Marcin; Miazga Zbigniew

来源：Journal of Rare Earths, 2016, 34(8): 843-849.

DOI：10.1016/S1002-0721(16)60104-7

• Nd15Fe79B6
• rare earths recycling
• hydrogenation disproportionation desorption and recombination (HDDR)
• ordered phase
• superlattice

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 degrees 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 degrees C. Remanence anisotropy was induced along an alignment direction when the temperature of the HDDR process was increased up to 800 degrees C and 850 degrees C for < 100 mu m and 100-160 mu m particles, respectively. Simultaneously, a small drop in coercivity was observed in the direction of alignment for < 100 mu m particles, but no for 100-160 m particles. Furthermore, probably an ordered phase was found by TEM microstructure analysis in the bulk sample dis-proportionated at 850 degrees C under 150 kPa of hydrogen. Grains with antiphase domains were observed and corresponding electron diffraction patterns were resolved, likely indicating superlattice structures.

• 出版日期2016-8