ORIENTATION RELATIONS OF NITRIDES IN IRON MADE BY ION-IMPLANTATION

The texture of the ion nitrides alpha '', epsilon-Fe2N1-x and gamma'-F e4N produced by N implantation into single-crystal iron has been deter mined by X-ray diffraction. By using two different single-crystal orie ntations, (111) and (001), the influence of substrate orientation coul d be determined. In the (111) Fe single crystal the close-packed plane s (CPPs) of the nitrides are always parallel to those CPPs of the iron which are perpendicular to the surface. In the (001) crystal the CPPs are almost but not exactly parallel to those CPPs of the iron which s tick out from the surface plane. A similar behaviour is observed for t he closed-packed directions (CPDs). The general observation for all ni trides is that CPPs and CPDs of the nitrides prefer to be parallel to CPPs and CPDs of the iron. In this way the interface energy is minimiz ed. Furthermore, slip occurs most easily along the CPPs and CPDs. Slip is needed to accommodate the volume expansion caused by the nitride f ormation. Finally, implant temperature and implant direction have no i nfluence on the texture of the epsilon-nitride. Knowing these relation s, it is possible to control the texture of iron nitrides by choosing the appropriate Fe substrate.