Abstract:Effects of milling and crystallization conditions on microstructure, such as amorphous phase and nanocrystalline phase, were investigated by X-ray diffractometry(XRD), differential scanning calorimetry(DSC), and transmission electron microscopy (TEM), respectively. The results show that nanocomposite Nd2Fe14B/α-Fe powder can be prepared by mechanical milling in argon atmosphere and a subsequent vacuum annealing treatment. The grain sizes of both Nd2Fe14B and α-Fe phase decrease drastically with increasing milling time. After milling for 5 h, the as-milled material consists of α-Fe nanocomposite phases with the grain size of 10 nm, and some amorphous phases, which can be turned into Nd2Fe14B/α-Fe nanocomposite phases by the subsequent annealing treatment. Milling energy of mechanical milling after 5 h by theoretical calculation is 6 154.25 kJ/g.

Key words: mechanical milling; crystallization treatment; Nd2Fe14B/α-Fe; grain size; milling energy