Phase formation and magnetic properties of annealed mechanical alloying Nd-Fe-V-Ti alloys and their nitrides

Phase formation in annealed mechanical alloyed NdFe10.5+x V1.5(1-x) Ti-x and magnetic properties of the consequent phases and their nitrides were investigated by using X-ray diffraction and magnetic measurement. From the X-rap diffraction patterns we have constructed a phase formation diagram as a function of Ti content x and annealing temperature. The demarcation curve between 1:7 and 1:12 phases moves to higher annealing temperatures with increasing Ti content. In the NdFe11 Ti alloy the ThMn12 structure is obtained by annealing the as-milled powder at temperatures above 950 degrees C. The nitrides NdFe10.5+0.5x V1.5(1-x) TixNy retain the same structure as their parent compounds. The nitride with high V content is more stable than that with low V content. Upon nitrogenation, the Curie temperature is enhanced from 150 degrees C to 180 degrees C. In NdFe10.5+0.5x V1.5(1-x) TixNyTc the values fall in the range 450-480 degrees C. The hard magnetic properties of NdFe10.5+0.5x V1.5(1-x) TixNy magnets have been assessed. (C) 1998 Elsevier Science S.A.