TEM INVESTIGATION OF NITROGEN-IMPLANTED MO FOIL

The synthesis and analysis of molybdenum nitrides formed during nitrog en ion implantation were investigated. Molybdenum foil samples were an nealed in vacuum at 1750 degrees C in order to grow large grains with low index preferential orientations. For comparison purposes, thin spe cimens were also cut from a (110) molybdenum single crystal. These sam ples were implanted with nitrogen at room temperature as well as at an elevated temperature of 370 degrees C. Doses of 1 x 10(17) N+ cm(-2) and 5 x 10(17) N+ cm(-2) were used at accelerating voltages of 50 kV a nd 100 kV. One nitride phase (MoN) and an unidentified phase were obse rved under the prevailing conditions. The morphology and orientation r elationships of nitride precipitates in the Mo lattice were examined b y transmission electron microscopy and electron diffraction. Depending on the surface orientation, both the Bain and the Nishiyama-Wasserman n orientations occurred. Implantation at 100 kV resulted in small miso rientated MoN precipitates that showed recrystallization and reorienta tion after annealing at 900 degrees C. Pulsed electron beam annealing (PEBA) at 0.6 J cm(-2) did not affect the nitride precipitates but res tored implantation damage in the molybdenum lattice. (C) 1998 Elsevier Science S.A.