Magnetic hardening of mechanically alloyed NdFe12−xVx (1⩽x⩽2) and their nitrides

The structure and permanent magnetic properties of isotropic powders of NdFe12-xVxNdelta compounds mere investigated by using mechanical alloying. It was found that heat treatment of as-milled powders at 700-900 degrees C resulted in the formation of Nd(Fe,V)(12) phase except for the sample with x = 1, for which the crystallization was not complete and a large amount of alpha-Fe(V) was present at temperatures lower than 750 degrees C. After nitrogenation, the volume expansion was about 5% and the Curie temperature enhancements were 140 to 160 degrees C. In NdFe12-xVxNdelta the values of T-c fall in the range 469-485 degrees C. It has been found that the intrinsic coercivities strongly increased with increasing V content. The maximum coercivity of H-i(c) = 10.96 kOe is achieved at 750 degrees C with x = 2.00. The difference between the coercivities of the mechanical alloyed Nd(Fe,V)(12)N-delta powders with different V content is attributed to their different crystallization behavior and phase stability during nitrogenation. (C) 1998 Elsevier Science B.V. All rights reserved.