Systematic insights into carbon deficiency induced structural characteristics, microstructural evolution and mechanical response in sputter-deposited TiCx films

Abstract

Titanium carbide (TiCₓ) is essential for extreme environments, owing to its exceptional properties that are inherently coupled to its carbon stoichiometry. This study systematically investigates the effect of carbon deficiency on the phase constitution, structural characteristics, microstructural evolution and mechanical properties of magnetron-sputtered TiCₓ films (x = 0.64–0.97). All TiC_x films retained the NaCl-type structure with carbon contents ranging from 39 at.% to 49 at.%. Carbon vacancies activate Raman-active modes, and the acoustic and optical phonons shifted systematically to higher wavenumbers as the C/Ti increases. Meanwhile, all films exhibited a columnar grain structure that gradually refines with increasing carbon content. The regulatory role of carbon content in these growth mechanisms is schematically illustrated and discussed. Among the studied compositions, the maximum value of hardness and modulus is determined to be 19 GPa and 369 GPa for TiC_0.93. This work establishes carbon vacancy engineering as an effective approach to tailor microstructure and mechanical performance.