We present a detailed investigation of the role of the disorder degree on magnetic properties for melt spun and die cast intermetallic Nd-Fe-Al-based alloys. For melt spun alloys, the roll speed was varied between 30 m/s and 5 m/s, which resulted in a clear dependence of coercivity on increasing roll speed, showing a steep decrease (from 250 kA/m to 10 kA/m). The results are interpreted in terms of a gradual transition from fully disordered microstructure (30 m/s sample) to short range ordered one (i.e., a clustered microstructure at 5 m/s), which is a consequence of a diminished cooling rate. On the other hand, die-cast alloy affords cluster formation due to this very low cooling rate compared with the melt spinning process and in consequence, coercivity values of 284 kA/m were observed. Further alloying addition (B, Cu, Dy) on the original Nd-Fe-Al composition, exhibited coercivity enhancement (up to 388 kA/m) due to the presence of small Nd-based crystallites, which act as pinning centers.
Email your librarian or administrator to recommend adding this journal to your organisation's collection.