K. S. Jung, R. E. Schacherl, E. Bischoff, E. J. Mittemeijer
May 31, 2013
Specimens of ferritic iron-based Fe-Ti-Cr alloys, containing a total of 0.30 at.% alloying elements, Ti and Cr with varying Ti/Cr atomic ratio (0.45, 0.87 and 1.90), were nitrided in a NH 3 /H 2 gas atmosphere at 580 °C. The microstructure of the nitrided zone was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Nitride platelets (length ≤ 30 nm and thickness ≤ 1 nm) developed in the nitrided zone. Particularly clear for the larger Ti/Cr atomic ratios, a tetragonally distorted ferrite develops next to the cubic ferrite, as evidenced both by XRD and TEM. The absence of separate TiN and CrN diffraction spots in the selected area electron diffraction patterns suggests the development of mixed Ti x Cr 1-x N nitride precipitates. The mixed Ti x Cr 1-x N nitride precipitates are of rock-salt crystal structure type and obey a Bain orientation relationship with the ferrite matrix.