Microholes processing in (TiZrHfNbTa)C high-entropy carbide ceramics via femtosecond laser: precision control and surface evolution mechanisms

(TiZrHfNbTa)C high-entropy ceramics are ideals for applications in ultra-high temperatures, corrosive, and high-irradiation environments due to their excellent thermal stability and mechanical properties. However, their exceptional hardness and inherent brittleness pose significant challenges to the fabrication of high-precision microholes via conventional machining techniques. In this study, femtosecond laser technology was employed to machine microholes in (TiZrHfNbTa)C ceramics, and the influence of processing parameters on the morphology and quality of microholes was thoroughly investigated. The results demonstrated that femtosecond lasers could create microholes with a diameter of 0.5 mm while producing minimal heat-affected zones around the holes. Dual-scanning protocol significantly reduced powder residue and decreased the microhole taper down to 0.004. After parameter optimization (5 W power, double scanning), the dimensional deviation between the hole entrance and exit was less than 1.7 %, resulting in an ultra-low taper of 0.001 and highly precise microholes. Furthermore, by combining surface plasmon excitation interference theory with the cold ablation characteristics of the material, this study elucidated the formation mechanism of periodic subwavelength laser-induced fringes and the principle of low thermal damage during processing. This study provides theoretical support and process optimization techniques for precision microstructure machining of high-entropy ceramics.