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 ceme nted 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 co lumnar microstructure. The intrinsic stress analyzed using the XRD sin(2)ps i 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 har dness and Young's 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 maxim um. The hardness for x = 0 (TiN) and x = 1 (TiC) were found to be 28 and 36 GPa, respectively. The Young's 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 i s suggested to be due to increased stability of defects created from the co llision 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 inf luence on the hardness of these films. (C) 2000 Published by Elsevier Scien ce S.A. All rights reserved.