高熵合金作為一新型合金系統，由於其結構簡單，所以利於分析、加工、合成以及利用，同時還擁有各種優異之物理及化學性質，可應用在各種工業，此外，其生產不需要特別之技術，並且可以很容易地利用現有之技術以及設備大規模來製造，由於上述所述種種原因，使其在各個領域都極具吸引力。但回顧近幾年之文獻，可以發現大家都把中心著重於開如何開發新之高熵合金系統，抑或是觀察添加一些微量元素藉此來提升現有之高熵合金系統的微結構及所需性能，鮮少關注在高熵合金去接合其他材料方面的研究，故本實驗利用已被完善研究之高熵合金：CoCrFeNi之高熵合金，來接合同樣在工業上具有良好之加工及機械性能，也會利用互補之特性來提升所需性能，被美稱為「太空金屬」之鈦，並研究其界面接面的反應，藉此來拓展高熵合金之應用領域。
本研究皆使用純度為99.9 wt.%之金屬，再利用電弧熔煉來製備合金，之後在1000°C之高溫爐持溫72小時作均質化處理，之後利用不銹鋼夾具製作CoCrFeNi/Ti 反應偶於1000-1100°C反應5-10小時。最後利用掃描式電子顯微鏡、能量分散光譜儀、電子微探儀以及X-ray繞射儀觀察其界面擴散層之組成以及各元素擴散之現象。
在CoCrFeNi/Ti 反應偶之結果中，各組持溫時間及持溫溫度反應下界面處所產生擴散層之相均類似，在靠近高熵金屬側均會形成各元素彼此互溶之FCC型之固溶體，整體來說，都沒有金屬間化合物生成。而各擴散層之厚度隨時間及溫度之增加會增厚。至於各元素之擴散，Ti在CoCrFeNi 高熵金屬側之擴散通量遠大於CoCrFeNi高熵金屬中各元素在Ti側之擴散通量，而CoCrFeNi高熵金屬中各元素擴散至Ti側之通量大小為Ni>Co>Fe >Cr。

As a new type of alloy system, high entropy alloy is easy to analyze, process, synthesize and utilize due to its simple structure. It also has various excellent physical and chemical properties and can be used in various industries. Furthermore, its production doesn’t require special technology. And it can be easily manufactured on a large scale by using existing technology and equipment. Due to the reasons mentioned above, it is very attractive in various fields. But reviewing the literature in recent years, we can find that everyone is focusing on how to develop a new high entropy alloy system, or observe the addition of elements to improve the microstructure and required performance of the existing high entropy alloy system, seldome focus on the research of high entropy alloy to join with other materials. Therefore, this experiment used the high entropy alloy system that has been well studied: CoCrFeNi, to join with Titanium, which also has good processing and mechanical properties, and studies the interfacial reaction to expand the application of high entropy alloys.
In this study, metal with a purity of 99.9 wt.% was used, using arc melting to prepare the alloy, and then put it in a high temperature furnace at 1000°C for 72 hours
for homogenization. Afterwards, CoCrFeNi/Ti reaction couple react at 1000-1100°C for 5-10 hours. Finally, using SEM, EDS, EPMA and XRD to observe the interface diffusion layer.
In the results of the CoCrFeNi/Ti reaction couple, the phases of the diffusion layers under different reaction temperatures and reaction time generated at the interface approximately the same. FCC type solid solutions would be generated on the side near the high entropy metal, but overall, there wouldn’t intermetallic compounds formed. The thickness of each diffusion layer would increase with the increase of reaction time and temperature. As for the diffusion results of each element, the diffusion flux of Ti on the CoCrFeNi high entropy alloy side was much greater than the diffusion flux of each element in the CoCrFeNi high entropy alloy on the Ti side, and the diffusion flux of each element in the CoCrFeNi high entropy metal was Ni > Co > Fe > Cr.

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