Lennart Karlsson

Self-organized nanostructures in the Ti-Al-N system

The phenomenon of age hardening could be evidenced in thin film applications. A model system, Ti1-xAlxN was chosen as such coatings are known for their excellent wear resistance enabling improved m ...

Thermal stability of arc evaporated high aluminum-content Ti1−xAlxN thin films

The thermal stability of Ti1−xAlxN films deposited by arc evaporation from Ti–Al cathodes with 67 and 75 at. % aluminum, respectively, has been investigated. The microstructure of as-deposited and ...

ION INDUCED STRESS GENERATION IN ARC-EVAPORATED TIN FILMS

The influence of Ti ion bombardment on the intrinsic stress and microstructure of TiN films during deposition by arc evaporation of Ti in pure N2 has been investigated. Ions with an average charge of +1.6 were accelerated from the arc discharge by a negative substrate bias Vs between 5 and 540 V which yielded a steady‐state substrate temperature between 300 and 600 °C, respectively. The compressive intrinsic stresses in the films, as determined by the x‐ray‐diffraction (XRD) sin2 ψ method after subtracting the thermal stress contribution at room temperature, changed abruptly from 1.9 to a maximum of 6.5 GPa as Vs increased from 5 to 100 V. The compressive stress then decreased monotonically to ∼1.6 GPa as Vs increased to 540 V. Broadening of XRD peaks (β) showed accompanying inhomogeneous strain with a maximum values for Vs=100 V. Cross‐sectional transmission electron microscopy showed a dense columnar film microstructure. Electron microdiffraction showed a distorted structure within the same columns for ...

Growth, microstructure, and mechanical properties of arc evaporated TiCxN1-x (0 <= x <= 1) films

TiCxN1-x films with x ranging from 0 to 1 were grown by arc evaporation by varying the flow ratio between the reactive gases. The substrates were cemented carbide inserts (WC-6 wt.% Co) which were negatively biased at 400 V, resulting in a deposition temperature of similar to 550 degrees C. The film composition, as measured by glow discharge optical emission spectroscopy, was found to vary almost linearly with the gas flow ratio. Cross-sectional transmission electron microscopy in combination with X-ray diffraction (XRD) showed that the films were of single-phase NaCl-structure with a dense columnar microstructure. The intrinsic stress analyzed using the XRD sin(2)psi method, was found to have a maximum of - 5.9 GPa in the composition range of 0.4 less than or equal to x less than or equal to 0.7 which correlated with a maximum in XRD peak broadening due to inhomogeneous strains. The hardness and Youngs modulus of the as-deposited TiCxN1-x films were measured by the nanoindentation technique. A maximum in hardness of 45 GPa was found at the same composition range (0.4 Ix I 0.7) as the intrinsic stress maximum. The hardness for x = 0 (TiN) and x = 1 (TiC) were found to be 28 and 36 GPa, respectively. The Youngs modulus was constant similar to 610 GPa for films with compositions up to x = 0.6, thereafter it decreased to 540 GPa at x = 1. The increase in intrinsic stress with increasing carbon content is suggested to be due to increased stability of defects created from the collision cascade or/and by a change in the defect structure itself. The fact that hardness showed a maximum at the same composition as residual stress and FWHM indicates that obstruction on dislocation movement has a major influence on the hardness of these films

Microstructural investigation of droplets in arc-evaporated TiN films

Abstract The microstructure and composition of macro particles (droplets) in TiN films deposited by arc evaporation on cemented-carbide substrates were investigated using a combination of scanning electron microscopy, cross-sectional transmission electron microscopy (TEM) including lattice resolution TEM, X-ray diffraction (XRD), energy-dispersive X-ray analysis and electron energy loss spectroscopy. The apparent surface number density of droplets, with diameters of 0.1–10 μm, was found to be about 10 7 cm −2 . Droplets were incorporated in the film at various distances from the substrate surface. In between the droplets, the TiN films exhibited a dense columnar microstructure. On top of the incorporated droplets, the TiN films grew in a pronounced columnar structure with a column diameter close to the droplet diameter. The core of the droplets consisted of equiaxed grains of an α-Ti superstructure containing approximately 3–5 at.% N whereas the rim of the droplets had increasing nitrogen content up to 50 at.% XRD showed evidence for the presence of Ti 2 N possibly at the rim of the droplets. Beneath each droplet a large voided region was observed with the shape of a flattened torus as a consequence of droplets being incorporated in the solid state and subsequent shadowing of the Ti flux to the film.

Thermally enhanced mechanical properties of arc evaporated Ti0.34Al0.66N/TiN multilayer coatings

Cubic metastable Ti0.34Al0.66N/TiN multilayer coatings of three different periods, 25+50, 12+25, and 6+12 nm, and monoliths of Ti0.34Al0.66N and TiN where grown by reactive arc evaporation. Differe ...