形狀記憶合金不同於一般金屬材料，擁有像是形狀記憶與擬彈性等特殊性質，但至目前為止其應用仍受到很大的侷限性，因此近年來有人提出「高熵合金」的概念結合記憶合金的性質，其特殊的機械性質與多元素組成為進一步發展打開新的研究領域。由於結合高熵合金概念的形狀記憶合金發展仍在非常基礎的階段，同時其對麻田散變形行為影響的研究並不充足，因此本研究對一系列鎳鈦合金包含傳統低熵NiTi合金、中熵NiCoTiZr合金與高熵NiCoFeTiZrHf合金進行結構與微觀機械行為的分析。本研究以X光繞射及背向電子繞射分析高熵合金與傳統合金的結構差異，並以奈米壓痕測試及臨場SEM微米柱壓縮對不同方向晶粒進行機械行為分析，再以STEM觀察高熵合金微米柱的變形行為。本實驗發現高熵合金相對於傳統合金在變形行為上有顯著的差異，既無形狀記憶行為，也非傳統差排長程滑移，此結果對於高熵合金結合記憶合金的未來研究方向提供重要訊息。

Shape memory alloys differ from traditional alloys because of its special features including the shape memory effect and the pseudoelastic effect. However, the application of these alloys still have some limitations. In recent years, the concept of high-entropy alloys has been combined with shape memory alloys. The special mechanical properties and elemental composition of high entropy alloys will develop completely new research areas. Since the development of high-entropy shape memory alloys is still at an early stage and the study of the deformation on martensitic transformation is not sufficient, therefore, this study focuses on the structure and microscopic mechanical behavior of nickel-titanium-based alloys including a traditional low-entropy NiTi alloy, a medium-entropy NiCoTiZr alloy and a high-entropy NiCoFeTiZrHf alloy. This study uses X-ray diffraction and electron back-scattered diffraction to clarify the difference of structure between these alloys. In addition, nanoindentation and in-situ SEM micropillar compression were used to analyze the mechanical behavior of different-orientation grains. STEM was used to observe the longitudinal section of the compressed micropillar. Experimental results indicated significant differences in the deformation behavior between the high-entropy alloy and the traditional alloy. The high-entropy alloy did not exhibit on shape memory effect or long-distance dislocation gliding. These results provide important information for exploring future research of high-entropy shape memory alloys.

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