Study on the diffraction patterns of alpha ''-Fe16N2 with Jack-1 and Jack-2 structural parameters

Two body centered tetragonal (bct) crystal structures of alpha"-Fe16N2 with x=0.25, z=0.3125 (Jack-1) and x=0.222, z=0.306 (Jack-2) respectively, were analyzed theoretically with EMS software package. The simulation of diffra ction patterns indicates that both diffraction patterns of the same axis in these two structures obey bcc extinction rule. The conclusion is also obta ined from the analyses of the diffracted waves. alpha"-Fe16N2 precipitates in the diffusion layer of ion-nitrided alpha-iron have been studied with tr ansmission electron microscope (TEM). We have distinctly observed the elect ron diffraction patterns of alpha"-Fe16N2 in [100], [111], [110], [011], [2 10], [021], [311], [113], [331] and [133] zone axes with perfect symmetry, which indicate the parallel orientation relationship with alpha matrix: <00 1>(alpha")//<001>(alpha), {100}(alpha")// {100}(alpha). The analyses of dif fraction patterns, which obey bcc extinction rule, verify the bet structure of alpha"-Fe16N2 discovered by X-ray diffraction.