Production and Characterization of Nanostructured Powders of Nd[sub.2]Fe[sub.14]B and Fe[sub.90]Al[sub.10] by Mechanical Alloying

The objective of this work is to evaluate the applicability of exchange coupling between nanoparticles of Nd[sub.2] Fe[sub.14] B (hard magnetic material) and Fe[sub.90] Al[sub.10] (soft magnetic material), as permanent magnets produced by surfactant-assisted mechanical alloying. The obtained powders were then mixed with 85% of the Nd[sub.2] Fe[sub.14] B system and 15% of the Fe[sub.90] Al[sub.10] system and subsequently sintered at 300 °C, 400 °C and 500 °C for one hour. The results obtained by Mössbauer spectrometry (MS) show a ferromagnetic behavior with six magnetic sites represented by sextets (16k1, 16k2, 8j1, 8j2, 4c and 4e), characteristic of the Nd[sub.2] Fe[sub.14] B system. X-ray diffraction (XRD) results show a tetragonal and BCC structure for the Nd[sub.2] Fe[sub.14] B and FeAl systems, respectively. The results obtained by vibrating sample magnetometry (VSM), for mixtures of the Nd[sub.2] Fe[sub.14] B and Fe[sub.90] Al[sub.10] sy stems sintered at 300 °C, 400 °C and 500 °C, allow for the conclusion that the coercive field (Hc) decreases drastically with temperature and the percentage of soft phase at values of Hc = 132 Oe compared to the coercive field values reported for Nd[sub.2] Fe[sub.14] B Hc = 6883 Oe, respectively. Images obtained by transmission electron microscopy (TEM), for the Fe[sub.90] Al[sub.10] system, show a tendency for the nanoparticles to agglomerate.