Structural, mechanical, optoelectronic and thermodynamic properties of bulk and film materials in Ti–Nb–C system: First-principles and experimental investigations

Both first-principles study of the random TiC–NbC solid solutions and experimental investigation of the films in Ti–Nb–C system were carried out. The mixing energy, electronic and phonon structures, elastic constants and moduli, hardness, Debye temperature, fracture toughness, dielectric function, electron energy-loss spectra and heat capacity of the random Ti1-xNbxC solid solutions were calculated and analyzed depending on composition. The Ti–C, Nb–C and Ti–Nb–C films were deposited by magnetron sputtering. The deposited films were comprehensively studied with XRD, XPS, AFM, EDS, Raman spectroscopy, indentation and tribological tests. The Ti–Nb–C films with equi-atomic composition are found to exhibit the highest Knoop hardness and lowest friction coefficient as compared to those of the parent TiC and NbC carbides. The results obtained were used to establish the mechanism of the stabilization of the TiC–NbC solid solutions, and to predict their structural, mechanical, optical and thermodynamic properties.