Residual stress in coated low-z films of TiC and TiN: II. correlation of residual stress with microstructure

Abstract

The correlations of the residual stresses with microstructures of TiC and TiN films deposited onto various substrates were examained by means of observations of SEM micrographs, X-ray back-reflected Debye rangs and diffraction line profile of X-ray spectorometer chart. It was found that specimens with lower residual stress generally show sharp line profile and good separation between K α2 and K α2 diffraction peaks in both TiN and TiC films, indicating better crystalline perfection. PVD coated TiC films on Mo and Inconel substrates show poor separation of K α2 and K α2 peaks, namely due to higher residual stresses in comparison with those of CVD coated TiN and TiC films on Mo or Inconel substrate. In CVD TiC/Pocographite system, with film thickness ranging from 10 to 100μm, the grain size increase with increasing the thickness, except 100μm thick specimen which has the smallest grain size in this group. However, the sharpness of diffraction profile is best in 20μm thick film, and worst in 100μm thick film. This is in good correlation with the amount of residual stress.