Influence of chemical composition on microstructure and properties of nanocrystalline Nd-Fe-B magnets produced by mechanical alloying

摘要

The nanocrystalline Nd_xFe_(94-x)B_6 (where x = 6, 11, 15 and 18) magnets produced by mechanical alloying were examined. The effect of chemical composition on microstructure applying optical and electron microscopy was studied. Using X-ray diffraction and Mossbauer spectroscopy the differences between equilibrium and real phase compositions were determined. The neodymium content essentially influences the grain size. The increase in the value of remanence associated with lower Nd concentration is ascribed to growing meaning of exchange interactions between grains (so called remanence enhancement effect). Moreover in the frame of micromagnetic theory the demagnetization curves were described in accordance with experimental data. Additionally, basic intrinsic magnetic parameters of nanocrystalline Nd-Fe-B magnet and its constituent phases were determined.