高压扭转后难熔高熵合金的热导率和电导率：电子与声子贡献
Thermal and electrical conductivity of a refractory high-entropy alloy after high-pressure torsion: Electron versus phonon contributions
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中文总结 AI 辅助
研究通过高压扭转处理难熔高熵合金TiZrHfNbTa，探讨纳米结构和缺陷工程对热导率和电导率的影响，分析电子与声子贡献，揭示热导率和电导率随应变的不同演化及原因。
中文摘要 AI 辅助
等原子难熔高熵合金TiZrHfNbTa通过高压扭转（HPT）处理，以研究纳米结构和缺陷工程对热输运和电输运性质的影响。HPT处理引起大量位错积累、晶粒细化至纳米级（平均40nm）以及从BCC相到ω相的部分转变。硬度随处理增加至稳态，比热容呈非单调行为。热导率在低应变时降低，高应变时略有恢复，电导率单调降低至稳态且无恢复。利用维德曼-夫兰兹定律分析表明，电子贡献主导热输运，声子贡献仅11%至23%。热导率和电导率的对比演化归因于从低应变时位错主导振动到高应变时晶界主导振动的转变。
英文摘要
The equiatomic refractory high-entropy alloy TiZrHfNbTa was processed by high-pressure torsion (HPT) to investigate the effect of nanostructuring and defect engineering on thermal and electrical transport properties. Severe plastic deformation (SPD) via the HPT treatment induces substantial accumulation of dislocations, grain refinement to the nanometer level (average: 40 nm), and partial transformation from the BCC phase to the omega phase. While hardness increases to a steady state with processing, the specific heat capacity exhibits a non-monotonic behavior: it decreases at low strains due to the suppression of low-frequency vibrational modes by dislocations, then partially recovers at high strains due to anharmonic vibrations at newly formed high-angle grain boundaries. Thermal conductivity decreases at low strains but shows a slight recovery at high strains, whereas electrical conductivity decreases monotonically to a steady state without recovery. Analysis using the Wiedemann-Franz law reveals that the electronic contribution dominates thermal transport, while the phononic contribution (limited by the scattering of phonons on defects) is only 11 to 23%, depending on the degree of straining. The contrasting evolution of thermal and electrical conductivity is ascribed to the transition from dislocation-dominated vibrations at low strains to grain boundary-dominated vibrations at high strains, which affects phonons and electrons with different efficiencies.
