Abstract This work presents a study on the thermoelectric properties of ultrafine grained Hf–Ti dual-doped VFeSb half-Heusler (HH) alloys treated by spark plasma sintering (SPS) at different temperatures. The concerned alloys were successfully synthesized by arc/induction melting and mechanical alloying (MA). Thermoelectric (TE) properties of Fe(V0.8Hf0.2)1-xTixSb (x = 0.0, 0.2, 0.4) HH samples were studied over the temperature range from 100 to 900 K. Hf and Ti as heavy elements were used as dopants to create point defects aiming to reduce the material's thermal conductivity by enhancing the phonon scattering. Since the transport properties of HH alloys are sensitive to heat treatment, the effect of sintering temperature is studied as well. It was found that the power factor is significantly improved by increasing the sintering temperature. As a result, the figure of merit was enhanced by ∼10% for the Fe(V0.8Hf0.2)0.8Ti0.2Sb sample and by ∼30% for the Fe(V0.8Hf0.2)0.6Ti0.4Sb sample which were sintered at 1123 K, compared to those sintered at 1023 K. The maximum value was recorded at 0.33 for the sample Fe(V0.8Hf0.2)Sb. This value is higher than that of the singly doped FeV0.9Hf0.1Sb sample with a maximum zT value of 0.08. Also, it is higher than the reported value of the FeVSb doped with Ti which shows maximum ZT of 0.174 calculated for FeV0.7Ti0.3Sb at 658 K.

中文翻译：

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放电等离子烧结对提高Hf-Ti掺杂VFeSb半赫斯勒合金热电性能的影响

摘要 这项工作研究了在不同温度下通过放电等离子烧结 (SPS) 处理的超细晶粒 Hf-Ti 双掺杂 VFeSb 半赫斯勒 (HH) 合金的热电性能。通过电弧/感应熔化和机械合金化（MA）成功合成了有关合金。在 100 到 900 K 的温度范围内研究了 Fe(V0.8Hf0.2)1-xTixSb (x = 0.0, 0.2, 0.4) HH 样品的热电 (TE) 特性。 Hf 和 Ti 作为重元素用作掺杂剂创建点缺陷，旨在通过增强声子散射来降低材料的热导率。由于 HH 合金的传输性能对热处理很敏感，因此也研究了烧结温度的影响。结果表明，提高烧结温度可以显着提高功率因数。结果，Fe(V0.8Hf0.2)0.8Ti0.2Sb 样品的品质因数提高了约 10%，而 Fe(V0.8Hf0.2)0.6Ti0.4Sb 样品的品质因数提高了约 30%。与在 1023 K 下烧结的那些相比，它们在 1123 K 下烧结。样品 Fe(V0.8Hf0.2)Sb 的最大值记录为 0.33。该值高于单掺杂 FeV0.9Hf0.1Sb 样品的值，最大 zT 值为 0.08。此外，它高于掺杂 Ti 的 FeVSb 的报告值，显示在 658 K 下对 FeV0.7Ti0.3Sb 计算的最大 ZT 为 0.174。该值高于单掺杂 FeV0.9Hf0.1Sb 样品的值，最大 zT 值为 0.08。此外，它高于掺杂 Ti 的 FeVSb 的报告值，该值显示在 658 K 下对 FeV0.7Ti0.3Sb 计算的最大 ZT 为 0.174。该值高于单掺杂 FeV0.9Hf0.1Sb 样品的值，最大 zT 值为 0.08。此外，它高于掺杂 Ti 的 FeVSb 的报告值，该值显示在 658 K 下对 FeV0.7Ti0.3Sb 计算的最大 ZT 为 0.174。