Post-treatment of titanium nitride by ion implantation

The properties of titanium nitride and the effects of a post-treatment by ion implantation on coatings made of it are first considered in terms of data available from the scientific literature; 70 references are cited. Data obtained in the present work are then combined with these to offer an explanation of the process mechanisms and structural effects involved. The present work covers monolithic TiN coatings, deposited onto cemented carbide by chemical vapor deposition or steel by physical vapor deposition, and implanted with gas or metal ions at different doses and acceleration energies. The results considered together confirm that large changes in the residual stress and the strain distributions are introduced into the implanted zone (IZ) and extend well beyond forming an implantation affected zone (IAZ) which extends to a depth of several microns The surface of the IZ is amorphized softened by non-metallic implants but not by metallic ions which increase the hardness. The residual stress in the IZ is high, tensile or compressive depending on whether vacancy generation and atom peening effects dominate and is accompanied by concomitant high, irregular, distributions of strain caused by a high dislocation density and/or grain comminution and include high fractions of lattice vacancies. The forward momentum of the ions introduces a dense dislocation network and high residual stress in the IAZ corresponding to the so-called long range effect. The dislocation density increases and the residual stress becomes more compressive with increasing ion momentum.