Speaker
Description
This study examines the nanoindentation behavior of polycrystalline hafnium carbide (HfC) and tantalum carbide (TaC) ceramics and validates the results through finite element (FE) simulation. The ceramics were synthesized via ball milling and a two-step Spark Plasma Sintering (SPS) process, producing uniform, single-phase samples. Electron backscatter diffraction (EBSD) was used to study orientation-dependent mechanical properties on the {001}, {101}, and {111} planes at room temperature.
HfC showed higher hardness on the {101} and {111} planes (~32 GPa) compared to {001} (~30 GPa), while TaC exhibited maximum hardness on the {111} plane (~23 GPa) and slightly lower values on {001} and {101} (~22 GPa). An axisymmetric FE model with a 70.3° conical indenter was used to simulate the indentation process. Simulated load-displacement curves aligned well with experimental data, supporting the observed trends. The orientation-dependent hardness variations were linked to active slip systems typical of rock-salt carbides. Minor discrepancies between simulation and experiment were negligible.
Hafnium carbide (HfC) and tantalum carbide (TaC) are ultra-high-temperature ceramics known for their exceptional thermal stability, hardness, and electrical conductivity. Although non-magnetic, they play a crucial role in magnetic applications under extreme conditions. In magnetic confinement fusion devices like tokamaks, they are used as plasma-facing materials due to their ability to endure intense thermal and particle flux without interfering with magnetic fields. Their chemical inertness and non-magnetic nature help maintain plasma stability and confinement. Recent studies have explored various ceramics for such applications [1,2]. Despite lacking magnetism, HfC and TaC are key to advancing magnetic technologies. This study specifically focuses on hardness, a fundamental characteristic necessary for withstanding extreme environment.
Acknowledgements
This research was supported by the Slovak Grant Agency for Science via the projects APVV-19-0497 and APVV-22-0493 and by the Slovak Academy of Sciences via the projects: Seal of Excellence - Strengthecs and IMPULZ IM-2022-67.
References
[1] A. Yehia, R. Vaßen, R. Duwe, and D. Stöver, “Ceramic SiC/B4C/TiC/C composites as plasma facing components for fusion reactors,” Journal of Nuclear Materials, vol.233-237, pp,1277-1270, 1996. https://doi.org/10.1016/S0022-3115(96)00155-9
[2] J. Linke, J. Du, T. Loewenhoff, G. Pintsuk, B. Spilker, I. Steudel and M. Wirtz, “Challenges for plasma-facing components in nuclear fusion,” Matter and Radiation at Extremes, vol. 4, no. 5, Art. no. 056201, Sep, 2019. https://doi.org/10.1063/1.5090100
