Sound graphite/graphite joints were obtained using ZrHfNbTa and TiZrHfTa alloys as interlayers using flash Spark Plasma Sintering (SPS) joining and conventional SPS joining. The ZrHfNbTa and TiZrHfTa foils showed a single high entropy phase. The influence of the two different interlayers and heat treatments were investigated. After flash SPS joining for 16 s, the joint structure showed a complete conversion of the ZrHfNbTa alloy interlayer to (Zr-Hf-Nb-Ta)C high entropy carbide due to the reaction between the interlayer and graphite, which resulted in a large residual stress caused by the mismatch of the coefficients of thermal expansion (CTE) between the graphite and joint. While the TiZrHfTa alloy interlayer showed a Hf-Zr rich carbide and Ti-Ta rich alloy structure, which led to an improvement of shear strength from 5.0 ± 2.9 MPa for the ZrHfNbTa joints to 19.3 ± 4.5 MPa for the TiZrHfTa joints, due to a reduction of the residual stress. After conventional SPS joining at 2000 °C for 30 min, both ZrHfNbTa and TiZrHfTa completely converted to (Zr-Hf-Nb-Ta)C or (Ti-Zr-Hf-Ta)C high entropy carbide without melting, and the shear strength reached 16.1 ± 2.8 MPa for the ZrHfNbTa joint and 19.5 ± 4.8 MPa for the TiZrHfTa joint. The relatively slower cooling rate compared to Flash-SPS joining produced a reduction of the residual stresses by annealing. A higher joining temperature or longer holding time had a limited effect on the shear strength when conventional SPS joining process was used.

使用 ZrHfNbTa 和 TiZrHfTa 合金作为中间层，使用闪光火花等离子烧结 (SPS) 连接和传统 SPS 连接获得了良好的石墨/石墨接头。ZrHfNbTa 和 TiZrHfTa 箔显示出单一的高熵相。研究了两种不同中间层和热处理的影响。闪速SPS连接16 s后，由于中间层与石墨的反应，接头结构显示ZrHfNbTa合金中间层完全转变为(Zr-Hf-Nb-Ta)C高熵碳化物，从而产生大量残余物。热膨胀系数不匹配引起的应力(CTE) 石墨与接头之间。而 TiZrHfTa 合金夹层呈现出富 Hf-Zr 碳化物和富 Ti-Ta 合金结构，这导致 TiZrHfTa 接头的剪切强度从 ZrHfNbTa 接头的 5.0 ± 2.9 MPa 提高到 TiZrHfTa 接头的 19.3 ± 4.5 MPa，这是由于减少残余应力。常规SPS连接在2000℃、30min后，ZrHfNbTa和TiZrHfTa均完全转化为(Zr-Hf-Nb-Ta)C或(Ti-Zr-Hf-Ta)C高熵碳化物，且未熔化，剪切强度提高ZrHfNbTa 接头达到 16.1 ± 2.8 MPa，TiZrHfTa 接头达到 19.5 ± 4.8 MPa。与 Flash-SPS 连接相比，冷却速率相对较慢，通过退火减少了残余应力。