Moessbauer Study of the Fe_3B/Nd_2Fe_(14)B Nanocomposite Magnet by the Addition of Co

摘要

The addition of Co to Nd_4Fe_(77.5-x)Co_xHf_(0.5)Ga_(0.5)B_(18.5) (0 ≤x≤5) was found to enhance the magnetic properties of Fe_3B/Nd_2Fe_(14)B nanocomposite magnets. The enhancement resulted from the fact that Co tends to retard the formation of Fe_3B from the amorphous matrix but to accelerate that of Nd_2Fe_(14)B. The decreased interval between the crystallization temperature of Fe_3B and Nd_2Fe_(14)B led to a uniform grain size distribution of both phases during the annealing treatment. The additive Co was confirmed to partition mainly to Nd_2Fe_(14)B crystals rather than to Fe_3B which was traced by XRD and Moessbauer spectroscopy as well. About 72 vol.% of Fe_3B, 27 vol.% of Nd2Fe_(14)B, and a small amount of Fe around 1 vol.%, respectively, were found to form. However, the volume fraction of each phase did not vary by the addition of Co up to 5 at.%.