Structure and magnetic properties of low-neodymium Nd-Fe-B powders by mechanical alloying

Low-neodymium Nd/sub 15-x/Fe/sub 77-2x/B/sub 8+3x/ powders were prepared by a mechanical alloying process using commercial Nd-Fe-B and Fe-B ingots as starting materials. Several iron boride phases, including Fe/sub 3/B, Fe/sub 2/B, and FeB, were observed to coexist with the Nd/sub 2/Fe/sub 14/B phase for the low-Nd compositions. Different process parameters are required to prepare low-Nd powders with optimum coercivity and microstructure. Coercivity of 10.5 to 4.5 kOe was obtained for x=0.0 to 4.5. The squareness ratio is close to an isotropic value of 0.5 for the studied compositions, indicating the interaction between nanoscale Nd/sub 2/Fe/sub 14/B and iron boride phases is not strong.