Thermal dependence of elastic properties of polycrystalline TiC0.97 and TiC0.40N0.60 alloys studied by surface Brillouin scattering

• An investigation of the Young’s modulus (E), shear modulus (G) and bulk modulus (B) of non-textured, non-stoicheometric polycrystalline compounds (TiC0.97 and TiC0.40N0.60) was conducted as a function of temperature, using SBS.
• The dependency of elastic moduli on temperature does not exhibit a quasi-linear behavior predicted by classical quasi- harmonic theory.

Transition metal carbides, nitrides and carbonitrides form an interesting class of compounds having an exceptional combination of physical properties including high melting points, high hardness values, high electrical and thermal conductivities and metallic lustre. Experimental information on the temperature dependence of the elastic properties of titanium carbide and nitride is scanty, and on titanium carbonitrides practically it is non-existent. An investigation of the Young's modulus (E), shear modulus (G) and bulk modulus (B) of these non-textured, non-stoichiometric polycrystalline compounds (TiC0.97 and TiC0.40N0.60) was conducted as a function of temperature, using surface Brillouin scattering (SBS). An approach utilising Rayleigh SAWs and an assumed Poisson's ratio was used to determine the elastic moduli E and B at room temperature as well as at high temperatures up to 700 °C. The variation of the elastic moduli with temperature points to the important influence of the intrinsic phonon–phonon interactions.