HARDNESS AND RESIDUAL STRESSES IN TiN-Ni NANOCOMPOSITE COATINGS DEPOSITED BY REACTIVE DUAL ION BEAM SPUTTERING

Abstract. Nanocomposite coatings of nc-TiN/a-Ni were deposited using an ultrahigh vacuum dual ion beam sputtering technique, which consist in sputtering a composite Ti-Ni target with 1.2 keV Ar+ ions while the growing film is bombarded with a mixture of 50 eV Ar+-N2+-N+ ions during depo-sition. Coatings hardness was measured using a nanoindenter equipped with a Berkovich dia-mond pyramid. The residual stress in the coatings was determined using XRD analysis and crys-tallite group method that is adapted to textured coatings and films. The results are compared to the conventional sin2ψ method. Our results show that for the films deposited at 573K the increase in Ni content results in a decrease of coating residual stresses. For films deposited at room tempera-ture residual stresses remain nearly constant, except around 5 at. % Ni where significant reduction is observed. For both temperatures, the hardness increases and exhibits a maximum in the range 5 to 10 at. % Ni. Our results show that the hardness enhancement in TiN-Ni nanocomposite coat-ings is not correlated with residual stresses, but rather to intrinsic nanostructure. 1