Characterization of nitrogenation of Sm/sub 2/Fe/sub 17/

Abstract

The role of hydrogen treatment before nitrogenation of Sm/sub 2/Fe/sub 17/ and the relation between nitrogenated conditions and nitrogen contents are examined. Many cracks occur in Sm/sub 2/Fe/sub 17/ particles during the hydrogenation process, and it is thought that hydrogen treatment increases the gas-solid reaction area significantly. The lower-temperature and longer-time nitrogenations are effective in reducing the amount of alpha -Fe phase, which decreases the hard magnetic properties. The analysis of nitrogen contents in a particle by EPMA (electron probe microanalysis) and experiments on magnetic properties show that it is important to obtain homogeneous Sm/sub 2/Fe/sub 17/N/sub x/ powder in order to make high-performance magnets. High-coercivity (12 kOe) and high-energy (28 MGOe) products were obtained as fine powders by optimizing the nitrogenation conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>