About this Abstract |
Meeting |
MS&T21: Materials Science & Technology
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Symposium
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High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond II
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Presentation Title |
Thermal Conductivity Reduction in (Zr<sub>0.25</sub>Ta<sub>0.25</sub>Nb<sub>0.25</sub>Ti<sub>0.25</sub>)C High Entropy Carbide from Extrinsic Lattice Defects |
Author(s) |
Cody A. Dennett, Fei Wang, Bai Cui |
On-Site Speaker (Planned) |
Cody A. Dennett |
Abstract Scope |
Thermal transport in high-entropy ceramics (HECs) is dramatically affected by the chemical disorder which stabilizes simple phases. However, with significant lattice contributions to thermal conductivity, structural defects should also play a meaningful role in the resulting material properties, though available experimental data is scarce. Here, we directly measurement thermal transport in bulk (Zr<sub>0.25</sub>Ta<sub>0.25</sub>Nb<sub>0.25</sub>Ti<sub>0.25</sub>)C which has been subjected to 3 MeV Zr ion beam irradiation at several temperatures to extrinsically impose lattice defects. The thermal conductivity of the defected layer is extracted using a spatial domain thermoreflectance (SDTR) technique and multi-layer thermal modeling. The thermal conductivity of specimens exposed to 8e15 ions/cm<sup>2</sup> is found to drop by ~15% at the lowest exposure temperature. A simple Debye approach to model lattice conductivity is combined with TEM-measured dislocation loop characteristics to quantify the excess reduction resulting from point defects. This work provides a foundation for additional routes to engineer low-conductivity, environmentally stable HECs. |