Effect of Si content on the properties of TiAl–Si–N films deposited by closed field unbalanced magnetron sputtering with vertical magnetron sources

In this work, a series of TiAl–Si–N films with Si content in the range from 0 to 3.6 at.% were deposited by closed field unbalanced magnetron sputtering (CFUBMS) with vertical magnetron sources. The chemical composition, crystalline structure and morphology of these films were characterized by AES, XRD, XPS and TEM. Also, their mechanical properties as a function of Si content were investigated by nanoindenter and wear tester. From our experimental results, it could be revealed that the present TiAl–Si–N films are nanocomposites, consisting of a nano-scale mixture of crystalline Ti1–xAlxN phase and amorphous Si3N4 phase. The hardness of films was strongly dependent on the Si content and the maximum hardness and elastic modulus of approximately 42 and 490 GPa, respectively, were measured for the film with the Si content of 2.1 at.%. Also, much improved wear resistance was observed compared to that of TiAlN film without Si content.