The effect of C content on the mechanical properties of Ti-Zr coatings

In this study, Ti-Zr and Ti-Zr-C coatings were deposited at room temperature via pulsed-DC magnetron sputtering. A 70Ti-30Zr at% target and a 99.99% graphite plate were used to deposit samples. In order to modify C content, coatings were deposited at different target powers such as 50, 75 and 100 W. Changes on the structure, microstructure and mechanical properties due to C addition were studied. Results indicate that the as-deposited coatings were partly crystalline and that an increment on C content stabilized α' phase and inhibited the appearance of ω precipitates. Therefore, Ti-Zr-C alloys with C>1.9 at% showed only α' phase whereas the others alloys exhibited α'+ω structures. Hardness values from 12.94 to 34.31 GPa were obtained, whereas the elastic modulus was found between 181.84 and 298 GPa. Finally, a high elastic recovery ratio (0.69-0.87) was observed as a function of composition. The overall properties of these coatings were improved due to C content increment, martensitic α' phase and nanocrystalline grain size (10-16 nm).