多重扩散阻挡效应的双相多主元合金中间层用于p型方钴矿热电材料电界面

Dual-phase multi-principal element alloy with syner-gistic diffusion barrier for p-type skutterudite ther-moelectric interfaces

摘要:

p型方钴矿及其电连接界面较差的热稳定性，严重制约了方钴矿基热电器件的可靠性。本文设计并制备了一种双相多主元合金中间层（CoFeNiMo0.75），通过Mo合金化，在保持热膨胀匹配的同时，构筑了多重扩散阻挡效应。固溶于面心立方（FCC）基体中的Mo加剧了晶格畸变，从而有效抑制了元素的扩散。而弥散分布的枝晶状富Mo的析出相（μ相）则表现出较低的反应活性，并显著增加了有效扩散路径的曲折度。得益于这种双相协同机制，CoFeNiMo0.75/La0.8Ti0.1Ga0.1Fe3.3Co0.7Sb12 界面表现出优异的热稳定性。在823 K下600 h热老化实验后，界面接触电阻率从仅约2.51 μΩ·cm2增加至3.22 μΩ·cm2，其演变遵循抛物线动力学规律，且具有极低速率常数（约为0.028 μΩ·cm2·h-1/2）。同时，界面剪切强度基本保持稳定（约16 MPa）。上述结果表明，双相策略在为下一代热电界面构建稳固、多层级的扩散阻挡层方面具有巨大潜力。

Abstract:

The inferior thermal stability of p-type skutterudites and their electrical contacts has severely limited the reliability of skutterudite-based thermoelectric devices. In this work, a dual-phase multi-principal element alloy interlayer, CoFeNiMo0.75, is engineered via adequate Mo alloying to establish a multiple diffusion barrier effect while maintaining thermal expansion matching. Mo dissolved in the FCC matrix intensifies lattice distortion to hinder elemental diffusion, while the dispersed dendritic Mo-rich μ-phase precipitates exhibit weak reactivity and increase the effective diffusion-path tortuosity. Owing to this dual-phase synergistic mechanism, the CoFeNiMo0.75/La0.8Ti0.1Ga0.1Fe3.3Co0.7Sb12 interface demonstrates exceptional thermal stability. After aging at 823 K for 600 h, the interfacial contact resistivity increased only from ~2.51 μΩ·cm2 to ~3.22 μΩ·cm2, following parabolic kinetics with an ultralow rate constant of ~0.028 μΩ·cm2·h-1/2, while the shear strength remained largely stable at ~16 MPa. These results showcase the potential of the dual-phase strategy in achieving robust, multi-level diffusion barriers for next-generation thermoelectric interfaces.