ON THE RESIDUAL-STRESS PROFILE DEVELOPED IN TITANIUM NITRIDE BY ION-IMPLANTATION

The effect of gas and metal ion implantation on the residual stress an d the strain distribution has been studied using glancing incidence pa rallel beam X-ray diffraction. Monolithic TiN coatings were chosen wit h very low residual stress as made by chemical vapor deposition onto c emented carbide. Implants of nitrogen, Ni-Ti dual and Y were made at d ifferent doses and acceleration energies. The results showed that the residual stress in the implanted zone was in the range 0.5 GPa tensile down to -2 GPa compressive, with very large distributions of strain c orresponding to high dislocation densities or gain comminution, With o ne exception, the residual stress below the implanted zone became tens ile up to 1 GPa down to depths of about 2 mu m with some increase in s train distribution. In the sample implanted with Y at high dose and en ergy the residual stress is highly compressive (-4 GPa), with a very h igh degree of strain broadening corresponding to a high degree of diso rder. Below this zone a tensile stress is developed associated with mo derate dislocation densities corresponding to a hardening of the mater ial. At high implantation doses and energies, the high compressive str ess and high dislocation density may correspond to a condition of over -implantation causing mechanical damage to the lattice.