Assessment of different X-ray stress measuring techniques for thin titanium nitride coatings

Three different X-ray stress measuring techniques have been applied to thin titanium nitride coatings: the classical d-sin(2)psi method, a low inciden t-beam-angle method and the crystallite-group method. The results are used for a comparison of the three methods. The influence of the crystallographi c texture is studied by considering a set of coatings with a strong (111) f ibre texture and another set with a weaker and mixed fibre texture. It is s hown that no significant differences in the stresses in the latter coatings are found using the three methods, whereas the coatings with strong (111) fibre texture exhibit compressive stresses that are significantly higher wh en the crystallite-group method is used. This is explained by the fact that (111)-oriented grains sustain stresses that are about 30% higher than thos e of the grains that show a deviation of 10 degrees from this orientation. Non-linearities in the d-sin(2)psi curves are reported that cannot be expla ined by means of linear elastic theories. (C) 2000 International Union of C rystallography Printed in Great Britain - all rights reserved.