Microstructure of mechanically alloyed Nd16Fe76B8-magnets

High resolution electron microscopy and analytical electron microscopy wereused to characterize mechanically alloyed Nd₁₆Fe₇₆B₈ which were previously identified as isotropic and anisotropic magnets. In both samples, two rare earth-oxide phases, NdO and Nd₂O₃, and a boron-rich phase were observed. Two grain boundary phases, the NdFe₂-phase and a non-equilibrium Nd-rich phase, were clearly identified in the isotropic samples and seem to be responsible for their higher coercivity. Due to the alignment of the grains, the anisotropic materials possess a better squareness of the B-H loop and a higher energy product.