Nitrogen ordering and ferromagnetic properties of ε-Fe3N1+x (0.10≤x≤0.39) and ε-Fe3(N0.80C0.20)1.38

The epsilon -phase iron nitrides epsilon -Fe3N1+x with x=0.10, 0.22, 0.30, 0.33, 0.39 and a carbonitride epsilon -Fe-3(N0.80C0.20)(1.38) were investigated by neutron diffraction, In these phases the non-metals occupy octahedral interstices in an hcp arrangement of Fe. Type and degree of occupational order of N and N+C, respectively were determined as a function of composition and temperature. The ordering of N is closely related to that of the epsilon -Fe3N 'ideal' structure (space group P6(3)22). Neutron diffraction data on epsilon -Fe3N1.22 revealed lowered symmetry (P312). An earlier proposed epsilon -Fe2N type ordering P (3) over bar 1m was not observed for the iron nitride samples but it was found for epsilon -Fe-3(N0.80C0.20)(1.38). Magnetisation data show that the nitride and carbonitride phases are soft ferromagnetic materials and confirmed magnetic structure data as derived from neutron diffraction. (C) 2001 Elsevier Science B.V. All rights reserved.