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The deformation mechanisms of a range of TiN coatings with different thicknesses, deposited on a V820 steel substrate following nanoindentation were characterized using focused ion beam (FIB) cross-sectioning and imaging, as well as cross-sectional transmission electron microscopy (TEM) of the indented region. Four TiN coatings were examined, including a cathodic arc evaporation (CAE) coating with a thickness of ∼ 0.7 μm and low voltage electron beam (LVEB) evaporation coatings with thicknesses of ∼ 2.0, ∼ 3.7 and ∼ 4.0 μm. Based on a model developed by Xie et al., the intercolumnar shear stresses were calculated to be approximately 2.20, 3.05, 3.50 and 3.55 GPa in the ∼ 0.7, ∼ 2.0, ∼ 3.7 and ∼ 4.0 μm thick TiN coatings respectively, that is, increasing as the coating thickness increases. Columnar cracking and shear steps at the coating/substrate interface were observed more frequently in the thinner TiN coatings indicated that these coatings deformed predominantly by shear along the columnar grain boundaries. In contrast, inclined cracking was the more dominant fracture type in the thicker TiN coatings. It is suggested that increased grain boundary strength occurs together with a lack of direct crack path along the grain boundaries through the thicker coatings due to the more equiaxed grain structure. Clearly, the grain structure and/or thickness of the TiN coating play a highly significant role in the deformation mechanisms. © 2009 Elsevier B.V. All rights reserved.

A TiN thin film coating, approximately 4 μm in thickness, deposited on a ductile steel substrate, was subject to surface deformation via nanoindentation using a spherical indenter, 5 μm in radius, with loads up to 500 mN. Pop-ins were observed during loading, which are characteristic of the onset of cracking and the formation of shear steps at the coating-substrate interface. Focused ion beam microscopy was used to prepare cross-sections through the indentation that revealed the presence of both intercolumnar and inclined cracks. Three-dimensional reconstructions of the deformation zone beneath the indentation were performed using a dual-beam focus ion beam instrument. These constructions provided more detailed images of the morphology of cracks, which were observed to be consistent with theoretical models of plastic deformation of such brittle coatings. © 2006 Elsevier B.V. All rights reserved.

The deformation mechanisms and mechanical properties of both TiN and TiAlN coatings on a V820 nitridable steel substrate have been investigated. Deformation was induced by nanoindentation, and the microstructures of the indented regions were studied using various techniques, including focused ion beam (FIB) and transmission electron microscopy (TEM). Two coatings deposited using a cathodic are process were investigated: a thicker (1.1 mu m) TiAlN-TiN dual-layer coating and a slightly thinner (0.7 mu m) TiN coating. Hardness was measured using nanoindentation using a 5-mu m-radius spherical indenter. A model developed by Korsunsky et al. was used to obtain the hardness of the coatings, accounting for both the thickness of the coating and the influence of the substrate. Hardnesses of 30 and 24 GPa were obtained for the TiAlN and TiN coatings, respectively. Both coatings exhibited broadly similar mechanisms of deformation. Columnar cracking and shear steps at the coating-substrate interface indicated that coatings deform predominantly by shearing along the columnar grain boundaries; however, significant lateral edge cracking was also observed, especially in the case of the TiAlN coating. The interface between the TiAlN and TiN in the dual-layer coating did not appear to affect the deformation behaviour.

The deformation mechanisms operating during nanoindentation of TiN coatings on steel substrates were investigated using FIB cross-sectioning and imaging, as well as cross-sectional transmission electron microscopy of the indented region. Two coatings were investigated: a relatively thick (3.7 μm) coating deposited using a low voltage electron beam system, and a thinner (0.7 μm) coating deposited using a cathodic arc process. Load displacement data from nanoindentation displayed clear pop-ins as the load increased. Cracks were observed at the boundaries between the columnar grains, and steps were observed at the coating/substrate interface. A comparison of the load displacement data and the microscopic observations indicated that deformation occurs primarily by shear sliding along the columnar grain boundaries. © 2004 Elsevier B.V. All rights reserved.

The microstructure and surface morphology of a TiN hard, wear resistant coating on a V820 nitridable alloy ductile steel substrate following nanoindentation have been characterized using focused ion beam (FIB) milling. ATiN coating, ∼0.6 (xm in thickness, was deposited on a ductile steel substrate using a cathodic arc evaporation (CAE) technique. Pop-in events were observed in the load-displacement curves and correlated to the observed microstructural features. Following nanoindentation with a 1 μm radius spherical indenter at loads of 100 mN and 500 mN, circumferential cracks were observed inside the indentation. Observations of nanoindented cross-sections prepared using FIB revealed both columnar cracks in the coating and shear steps at the coating-substrate interface. These structural features were observed at higher resolution using a transmission electron microscope (TEM). © 2004 Elsevier B.V. All rights reserved.

TiN and TiAlN/TiN PVD coatings deposited onto as-ground surfaces have been characterised via direct cross-sectional imaging and transmission electron microscopy with the aid of a focused ion beam system. Cross-sections showed that the coatings exhibit consistent coverage, even in sheltered areas such as at the base of grooves resulting from prior grinding. A columnar grain structure was observed in all coatings. A number of defects were observed such as seams and voids resulting from coating onto the as-ground surface and macroparticles which were shown to be deposited during the metal ion etching stage. Cross-sections through nanoindents revealed that the coatings deform by through-thickness shear cracking. The combination of the excellent coverage provided by PVD and the deformation mechanisms, which are related to the microstructure, contribute to the excellent performance of these coatings that has lead to their widespread application.