Composition and microstructure of titanium nitride formed on Ti6Al4V by nitrogen plasma immersion ion implantation

Ti6Al4V has been treated with nitrogen Plasma Immersion Ion Implantation (PIII). Implantations with high-voltage pulses have been carried out at 50- and 400-Hz pulse repetition rates for varying process limes in a nitrogen plasma generated by electron cyclotron resonance (ECR) microwave excitation. Due to the different power input at these repetition rates, the corresponding sample temperature reached 200 and 450 degrees C, respectively. Nitride formation was studied in relation to the retained dose. The composition of the modified surface layer was determined by elastic recoil detection analysis (ERD), and the structure and morphology were studied by means of X-ray diffraction (XRD) and cross-section transmission electron microscopy (XTEM). The nitrogen content increases with total pulse number irrespective of the pulse repetition rate. Nitride formation could be proved by the presence of the (200) TiN reflection. A homogeneous fine crystalline TiN layer was built up, exhibiting a strong crystallographic orientation relationship to the substrate grains. (C) 1998 Elsevier Science S.A.