COMPOSITION AND MICROSTRUCTURE OF TITANIUM NITRIDE FORMED ON TI6AL4V BY NITROGEN PLASMA IMMERSION ION-IMPLANTATION

Ti6Al4V has been treated with nitrogen Plasma Immersion Ion Implantati on (PIII). Implantations with high-voltage pulses have been carried ou t at 50- and 400-Hz pulse repetition rates for varying process limes i n a nitrogen plasma generated by electron cyclotron resonance (ECR) mi crowave excitation. Due to the different power input at these repetiti on rates, the corresponding sample temperature reached 200 and 450 deg rees C, respectively. Nitride formation was studied in relation to the retained dose. The composition of the modified surface layer was dete rmined by elastic recoil detection analysis (ERD), and the structure a nd morphology were studied by means of X-ray diffraction (XRD) and cro ss-section transmission electron microscopy (XTEM). The nitrogen conte nt increases with total pulse number irrespective of the pulse repetit ion rate. Nitride formation could be proved by the presence of the (20 0) TiN reflection. A homogeneous fine crystalline TiN layer was built up, exhibiting a strong crystallographic orientation relationship to t he substrate grains. (C) 1998 Elsevier Science S.A.