Microstructural effects on indentation failure mechanisms in TiN coatings: Finite element simulations

Titanium nitride (TiN) coatings offer improvements in resistance to wear and environmental degradation. TiN films produced by physical vapour deposition tend to exhibit columnar grain structures, with attendant anisotropies in elastic and fracture properties that influence mechanical behaviour during instrumented indentation. However, computational simulations of indentation behaviour to date have treated TiN films as homogeneous and isotropic. In the present study, nanoindentation of TiN coatings on ductile substrates is simulated and resultant deformation and damage mechanisms are predicted. Intergranular sliding that occurs due to the columnar grain structure is incorporated into the model via anisotropic property definitions and nodal coupling. Substrate and coating properties are calibrated by comparison with previously obtained experimental results. Effects of coating thickness, substrate ductility and residual stresses on coating deformation processes and failure mechanisms are established.