Spark plasma sintering Nd2Fe14B/α-Fe bulk exchange-spring magnets

The Nd2Fe14B/a - Fe bulk exchange-spring magnets have been prepared by spark plasma sintering melt spun Nd9.8Dy0.4Fe78Co5.6B5.8 flakes under different temperatures and pressures. It was found that higher sintering temperature improved the densification of the magnets, while deteriorated their magnetic properties simultaneously. An increased compressive pressure can restrain the grain growth remarkably and then leads to better magnetic properties and higher density for the magnet at same sintering temperature. XRD analysis showed that with the increase of sintering pressure, some peaks indicating c-axis texture such as (006) and (105) became dominant. As a result, the bulk magnet exhibited higher remanence and maximum energy product than starting powders.