First-Principles-Informed Modeling of Thermal Transport and Laser-Induced Heating in Ultrahigh-Temperature Carbides
Using first-principles density functional theory and Boltzmann transport calculations, we systematically investigate the electronic structure, lattice and electronic thermal transport, optical response, and laser-induced heating of ultrahigh-temperature carbides (UHTCs), including Group IV (TiC, ZrC, and HfC) and Group V carbides (VC, NbC, and TaC), and SiC. The transition-metal carbides (TMCs) exhibit metallic electronic structures, whereas SiC exhibits semiconducting character. The calculated thermal transport properties reveal distinct contributions from phonons and electrons, with electronic heat transport becoming increasingly important at elevated temperatures in TMCs. The Group V carbides exhibit substantially lower lattice thermal conductivity than their Group IV counterparts, accompanied by pronounced Kohn anomalies and modified phonon dispersions associated with their distinct electronic structures, suggesting a possible connection between Fermi-surface topology, phonon dynamics, and lattice thermal transport. In contrast, SiC exhibits comparatively high lattice thermal conductivity, consistent with its long-lived acoustic phonons, but no electronic contribution due to its semiconducting nature. Optical calculations reveal relatively high reflectivity in the visible and infrared spectral ranges for the metallic carbides, whereas SiC exhibits lower reflectivity in the infrared region. Finally, one-dimensional and three-dimensional continuum heat-conduction models are employed to compare the thermal responses of these materials under specified laser irradiation conditions. The predicted temperature distributions depend on the thermal and optical properties of the materials as well as the specimen geometry.