In situ neutron diffraction study of the nitrogenation process applied to NdFe10.5V1.5 alloys

The RFe12−XMX compounds (R = Pr, Nd; M = Ti, V, Cr, Mn, Mo, Nb), known as the 1:12 phases, are interesting as potential permanent magnets due to their high magnetisation level. For example, the NdFe10.5V1.5Ny phase present higher intrinsic magnetic properties than the Nd2Fe14B phase when the compound is fully and homogeneously nitrogenated. The in situ neutron diffraction allowed us to identify two different mechanisms for the nitrogenation reaction of NdFe10.5V1.5 samples that can account for the necessary temperature optimisation of the nitrogenation step. Two different behaviours observed on nitrogenation of annealed or HDDR-processed powders also suggest that the starting microstructure of the powder is a key parameter in the nitrogenation process.