現今高溫合金主要由超合金所構成，但目前超合金工作溫度已達其使用極限。過去十年內，由清華大學提出的高熵合金逐漸受到各界學者重視，由於組成元素種類眾多，原子間尺寸差異導致局部化學能擾動及嚴重晶格扭曲效應，造就了許多異於傳統合金的材料特性。其中，BCC結構的耐火高熵合金在高溫下具有優異的機械性質，能夠維持相穩定性，同時具備極佳的抗軟化能力，但目前已開發的BCC耐火高熵合金仍面臨室溫延展性及高溫強度的取捨。因此本實驗利用改進之新成分HfMoNbTaTiZr及HfMo0.5NbTaTiZrV0.5進行基本性質分析與機械性質的量測。基本性質分析包含XRD晶體結構鑑定、EBSD結晶取向鑑定、EDS成分分析，機械性質部分則包含奈米壓痕測試、臨場SEM微米柱壓縮、巨觀壓縮測試等。並且再透過微量添加硼元素來改善機械性質。綜合上述分析，本實驗發現利用調控成分組成及添加微量溶質原子，能改善BCC耐火高熵合金於室溫下強度及延性表現，在不過度犧牲延展性的前提下成功提升材料強度，為未來工程合金應用開闢新的道路。

　Nowadays, superalloys are mainly composed of superalloys, but the current working temperature of superalloys has reached its limit. In the past ten years, the high-entropy alloys have gradually attracted the attention of scholars. Due to multiple constituent elements, the size differences between atoms lead to local chemical energy disturbances and severe lattice distortion effects, creating many materials that are different from traditional alloys characteristics. Among them, refractory high-entropy alloys with BCC structures have excellent mechanical properties at high temperatures. It can maintain phase stability and have excellent softening resistance, but the currently developed BCC refractory high-entropy alloys still face the strength–ductility trade-off at room temperature and high temperature. Therefore, this study focuses on the basic properties and mechanical behavior of improved new components, HfMoNbTaTiZr and HfMo0.5NbTaTiZrV0.5. In this study, the basic properties were carried out using X-ray diffraction, electron back-scattered, and energy-dispersive X-ray spectroscopy. In addition, nanoindentation, in-situ SEM micropillar compression test, and macroscopic compression test were used to analyze the mechanical properties. And then adding a small amount of boron to improve the mechanical properties. Based on the above analysis, this experiment found that the strength and ductility performance of BCC refractory high-entropy alloys at room temperatures can be improved by adjusting the composition and adding trace solute atoms, and the strength of the material can be improved without excessive sacrificing ductility.

致謝 I
摘要 II
Abstract III
目錄 IV
圖目錄 VII
表目錄 XIV
壹、前言 1
貳、文獻回顧 2
2-1 高熵合金 2
2-1-1 高熵合金發展 2
2-1-2 四大核心效應 5
2-1-3 不同溫度下高熵合金之特殊性質表現 7
2-2 高熵合金之機械行為 11
2-2-1 部分差排與疊差 11
2-2-2 變形雙晶 13
2-2-3 相變誘發塑性 15
2-2-4 交叉滑移 17
2-2-5 BCC高熵合金強度來源 19
2-3 異質結構高熵合金 27
2-3-1 異質高熵合金 27
2-3-2 異質材料的變形行為 29
2-3-3 多相異質結構 31
2-3-4 單相異質結構 35
2-4 間隙型異質結構高熵合金 36
2-4-1 間隙型異質高熵合金 36
2-4-2 硼原子對晶界之影響 38
2-4-3 硼對晶粒之影響 41
2-5 研究目的 43
參、實驗步驟 44
3-1 實驗規劃 44
3-2 實驗流程 45
3-2-1 高熵合金試片製備 45
3-2-2 高熵合金試片基本性質 47
3-2-3 XRD 晶體結構分析 49
3-2-4 EDS 組成成分分析 49
3-2-5 EBSD 晶粒方向鑑定 49
3-2-6 巨觀壓縮測試 49
3-2-7 XPM機械性質量測 51
3-2-8 聚焦離子束 (FIB) 微米柱試片製備 53
3-2-9 臨場SEM微米柱壓縮測試 55
肆、結果與討論 57
4-1 XRD晶體結構鑑定 57
4-2 SEM微結構及EDS組成成分分析 59
4-3 晶粒方向及相鑑定 64
4-4 維氏硬度分析 68
4-5 奈米壓痕測試分析 70
4-6 室溫臨場微米柱壓縮測試 80
4-7 室溫巨觀壓縮測試 87
4-8 室溫巨觀壓縮測試斷裂面 93
伍、結論 96
陸、參考文獻 99

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