Ion implantation processing of sub-stoichiometric titanium nitrides and carbonitrides: Chemical structural and micromechanical investigations

Sub-stoichiometric titanium nitrides TiNx (x = 0.25, 0.45 and 0.61) and carbonitride TiNxCy (x = 4 = 0.35) were synthesized at the titanium surface by multiple energy (180, 100, 50 and 20 keV) ion implantation. The in-depth distributions of carbon and nitrogen deduced from RBS and SIMS spectra were compared with TRIM calculations. From the X-ray grazing incidence we observed the following structures: (i) An NaCl type structure for TiN0.35C0.35 and TiN0.25, the latter is commonly known as delta-titanium nitride; (ii) A nitrogen solid solution in an alpha-Ti structure for TiN0.25, and a mixture of both structures for TiN0.45 In the case of the NaCl structures, the layers were composed of very small strained crystallites (nanocrystals). X-ray photoelectron spectroscopy of C 1s, N 1s and Ti 2p levels, as well as the valence band spectrum, show that the carbon and the nitrogen are fully bonded to titanium. Nanoindentation measurements show an elastoplastic behavior for the layers. The hardness and Young's modulus were derived from load-displacement curves. The results were discussed in the light of the published work.