形狀記憶合金具有兩大特性，形狀記憶效應和超彈性效應，目前應用最多且性質最好的形狀記憶合金為鎳鈦合金 (Nitinol)，但其相轉換溫度僅在室溫，故侷限其應用環境。為了使形狀記憶合金能應用廣泛，展開對高溫形狀記憶合金的研究發展。
本研究致力於發展高溫形狀記憶合金，藉由添加額外元素達到提升相轉換溫度的效果，形成高溫形狀記憶合金，但由於文獻研究之高溫形狀記憶合金的成形性和加工性差，且其機械性質不佳。所以，本研究以高熵合金的設計概念，探討高溫高熵形狀記憶合金，利用高熵合金的特殊性質，提升其機械性質並同時提升相轉換溫度，亦即發展出可應用於高溫的形狀記憶合金，並展現高熵效應之獨特性。

Shape memory alloys own two effects: shape memory effect and pseudo-elasticity. And so far, Nitinol is the widely used shape memory alloy which demonstrates good ductility and strength. However, Nitinol only has a limited range of martensitic transformation temperature from 0℃ to 100℃. In order to expand the applications of shape memory alloys in temperatures above 100℃, the research field of high temperature shape memory alloys become highly desirable. Currently, high temperature shape memory alloys have shown poor ductility and workability. So this study aims to develop a new high temperature shape memory alloy with good ductility. Additionally, this new alloy is combined with the concept of high-entropy alloys to enhance its ductility and strength at the same time.

壹、 前言 1
貳、 文獻回顧 4
2-1 高熵合金概念 4
2-2 高熵形狀記憶合金概念 5
2-3 形狀記憶合金 8
2-3.1 超彈性 9
2-3.2 形狀記憶效應 10
2-3.3 遲滯區間 (Hysteresis) 13
2-4 麻田散體相變化 (Martensitic transformation) 14
2-5 形狀記憶效應的優劣 16
2-6 高溫形狀記憶合金 18
2-7 Ni-Ti 形狀記憶合金的晶體結構 19
2-8 Ni-Ti 形狀記憶合金的拉伸性質 22
2-9 Ni-Ti 形狀記憶合金的detwinning過程在拉伸和壓縮的異向性 24
2-10 形狀記憶效應試驗 27
2-10.1 試驗方法 27
2-10.2 回復量與不可回復量 28
2-11 雙向形狀記憶效應 31
2-12 Hf 和 Zr 添加的影響 34
2-12.1 提升相轉換溫度 34
2-12.2 添加 Hf 和 Z r之缺點 36
2-12.3 Ni-Ti-Hf-Zr 四元高溫形狀記憶合金 38
2-13 應力對相轉換溫度的影響 39
參、 實驗步驟 41
3-1 實驗流程簡介 41
3-2 實驗流程 46
3-3 試片編號 46
3-3.1 第一系列 46
3-3.2 第二系列 46
3-3.3 第三系列 47
3-3.4 第四系列 47
3-4 高熵合金相預測和模擬 47
3-4.1 混和熵 (ΔSmix) 47
3-4.2 混和焓 (ΔHmix) 48
3-4.3 原子尺寸差異 (δ) 48
3-5 真空電弧熔煉 (Vacuum Arc Melting, VAM) 49
3-6 X-ray 晶體繞射分析 (X-ray Diffraction, XRD) 49
3-7 高溫 X-ray 晶體繞射 (High-temperature X-ray Diffraction) 50
3-8 X-ray繞射分析方法 50
3-9 熱膨脹分析儀 (Dilatometer, DIL) 51
3-10 掃描式電子顯微鏡 (Scanning electron microscope, SEM) 52
3-11 熱式差掃描量測儀 (Differential scanning , DSC) 52
3-12 壓縮試驗 53
3-13 形狀記憶效應測試法 53
3-13.1 實驗方法 53
3-13.2 實際實驗流程 54
肆、 實驗結果 58
4-1 高熵合金相模擬預測 58
4-2 第一系列 59
4-2.1 鑄造性質與微結構 59
4-2.2 壓縮機械性質 62
4-2.3 相轉換溫度 62
4-3 第二系列 63
4-3.1 鑄造性質與微結構 63
4-3.2 X-ray 繞射分析 64
4-4 第三系列 66
4-4.1 熱膨脹試驗 (DIL) 67
4-4.2 室溫 X-ray 繞射分析 69
4-4.3 高溫 X-ray 繞射分析 71
4-4.4 微結構 73
4-4.5 壓縮試驗 75
4-5 第四系列 76
4-5.1 熱膨脹試驗 (DIL) 76
4-5.2 熱式差掃描試驗 (DSC) 78
4-5.3 熱循環試驗 (DIL) 81
4-5.4 微結構 83
4-5.5 室溫 X-ray 繞射分析和高溫 X-ray 繞射分析 84
4-5.6 壓縮試驗 91
4-5.7 形狀記憶效應試驗和相轉換溫度 93
伍、 實驗結果討論 102
5-1 麻田散體和沃氏田體相變化之體積變化 102
5-2 麻田散體相變化溫度 103
5-3 Co元素的添加影響 104
5-4 Cu 添加的影響 106
5-4.1 對晶體結構與晶格常數之影響 106
5-4.2 對相轉換溫度之影響 108
5-4.3 對機械性質之影響 109
5-5 添加 Hf 和 Zr 之影響 110
5-5.1 對晶體結構和晶格常數之影響 110
5-5.2 對壓縮性質的影響 111
5-6 施加應力對相變化溫度的影響 112
5-7 雙向形狀記憶效應 113
5-8 高熵形狀記憶合金 114
陸、 結論 115
柒、 本研究之貢獻 117
7-1 對形狀記憶合金領域 117
7-2 對高性能合金實驗室 117
捌、 參考文獻 118

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