Consolidation of Fe-Co-Nd-Dy-B glassy powders by spark-plasma sintering and magnetic properties of the consolidated alloys

Abstract

Consolidation of Fe67Co9.5Nd3Dy0.5B20 glassy powders has been tried by spark-plasma sintering (SPS) at around the glass transition temperature in order to synthesize a hard magnetic bulk material with a nanocomposite structure. The glassy powders were consolidated into bulk forms with relative densities above 97% by the sintering at 788 K and over. The sample sintered for 420 s at 788 K had a nearly full density of 99.1% and still kept a glassy single phase. The increase in the sintering temperature and time caused by crystallization and the formation of Fe3B phase. These as-sintered samples exhibited soft magnetic characteristics, but the soft magnetism changed to a hard type by annealing to form Nd2Fe14B, Fe3B and α-Fe phases. The remanence, coercivity and maximum energy product for the bulk compact sintered for 420s at 788 K, followed by annealing for 600 s at 913 K were 1.03 T, 277 kA/m and 83.1 kJ/m3, respectively.