Influence of milling conditions on magnetic properties of Sm/sub 2/Fe/sub 17/N/sub 3/ particles

Ball milling conditions were examined for the preparation of fine Sm/sub 2/Fe/sub 17/N/sub 3/ particles. The milling process with high ball/bottle volume ratio produced Sm/sub 2/Fe/sub 17/N/sub 3/ particles with low /sub i/H/sub c/ and 4 /spl pi/I/sub r/. The decrease in 4 /spl pi/I/sub r/ and /sub i/H/sub c/ were attributed to particle aggregates formed during the milling. The addition of a surfactant (e,g. polystearic acid) prevented aggregation in the ball milling, and yielded high-performance Sm/sub 2/Fe/sub 17/N/sub 3/ particles (4 /spl pi/I/sub r/: 14.1 kG, /sub i/H/sub c/: 9 kOe, (BW)max: 34 MGOe); cf. (BH)max=20 MGOe for typical epoxy-bonded magnets.