本研究為改善σ相在合金當中會使機械性質劣化的情形，以許經佑學長所探討的AlCoCrFeMo0.5Ni高熵合金中樹枝相及樹枝間相的σ相成份為基礎，利用雙相結構(BCC + σ)提升合金的破壞韌性，而後再進行微量添加、成份變量與熱處理使合金的硬度值與破壞韌性再進一步得到提升。
此合金系統的微結構可分為四種：第一種是樹枝狀結構；第二種是樹枝狀結構 + 共晶結構；第三種是有明顯晶界的多晶結構；第四種則是細微交錯的雙相結構。合金結構的變化受到添加元素的種類及含量所影響：Al元素促進BCC相形成，但會抑制σ相；Ni元素促進FCC相形成；Cr和Mo元素會促進σ相形成。合金的硬度值基本上由三個相所佔的比例決定，分別為最硬的σ相，次硬的BCC相，最軟的FCC相。
經由硬度試驗後硬度壓痕周圍的裂痕總長，能夠換算成破壞韌性用來比較各合金的韌性。當合金微結構呈現細微的交錯結構時，壓痕周圍不會出現裂痕，表示合金具有很好的韌性，如Alx(Co17.7Cr28.3Fe20.3Mo16.6Ni9.5)100-x系列高熵合金中，Al15、Al20合金硬度壓痕周圍沒有產生裂痕，且硬度值分別為HV 850與HV 807，比學長的AlCoCrFeMo0.5Ni高熵合金HV 728要高出許多，此外，AlCoCrFeMo0.5Ni合金的硬度壓痕周圍有產生裂痕。
Al15、Al20合金除了室溫硬度值與破壞韌性表現很好外，高溫硬度值表現更是相當優異，從室溫到1000℃的硬度值皆比Co基超合金T-800、Ni基超合金In 718與AlCoCrFeMo0.5Ni合金高出許多，且在400℃時硬度值沒有快速下降的趨勢，在1000℃時Al15合金的硬度值有HV 600，遠比T-800與In 718的HV 151與HV 127高。高熵合金能夠擁有如此優異的高溫硬度性質，原因主要為高熵效應使多種合金元素形成BCC、FCC及高硬度的σ相，這些固溶相在高溫下仍能有效地固溶強化，且因多元素原子對空缺的競爭，降低空缺擴散速率及與空缺擴散有關的變形機制。

Abstract I
摘 要 II
誌 謝 IV
目 錄 V
圖目錄 IX
表目錄 XVI
壹、 前 言 1
貳、 文獻回顧 3
2.1 超合金 3
2.2 介金屬化合物 7
2.2.1 電子化合物 7
2.2.2 σ相簡介 9
2.3 Stellite合金 11
2.4 高熵合金 15
2.4.1 開發背景 15
2.4.2 高熵合金的特色 16
2.4.3 本研究之目的 25
參、 實驗方法 29
3.1 合金製備與實驗流程 29
3.1.1 合金製備與設計 29
3.1.2 實驗流程 29
3.1.3 真空電弧熔煉 33
3.1.4 均質化處理 33
3.1.5 時效處理 34
3.2 X-ray 繞射分析 34
3.3 微結構觀察與成份分析 36
3.3.1 掃描式電子顯微鏡 (SEM) 36
3.4 室溫硬度與破壞韌性 (K1C) 36
3.5 高溫硬度量測 38
3.6 DTA熱分析 38
肆、 結果與討論 40
4.1 AlCoCrFeMo0.5Ni高熵合金中的σ相探討 40
4.1.1 樹枝相與樹枝間相中σ相的結構與機械性質 40
4.2 不同Al含量Alx(Co17.7Cr28.3Fe20.3Mo16.6Ni9.5)100-x高熵合金的探討 45
4.2.1 Al含量對晶體結構的影響 45
4.2.2 Al含量對微結構的影響 47
4.2.3 Alx(Co17.7Cr28.3Fe20.3Mo16.6Ni9.5)100-x合金的硬度與破壞韌性 56
4.2.4 Al15、Al20合金的DTA分析 59
4.2.5 Al15、Al20合金的高溫硬度 61
4.3 不同Ni含量Nix(Al10Co17.2Cr27.6Fe19.8Mo16.2)100-x高熵合金的探討 65
4.3.1 Ni含量對晶體結構的影響 65
4.3.2 Ni含量對微結構與機械性質的影響 67
4.4 微量添加元素對Al15Co16.3Cr26Fe18.7Mo15.3Ni8.7合金的探討 75
4.4.1 微量添加Hf對結構與機械性質的影響 75
4.4.2 微量添加Nb對結構與機械性質的影響 79
4.4.3 微量添加Ta對結構與機械性質的影響 83
4.4.4 微量添加Ti對結構與機械性質的影響 87
4.4.5 微量添加Zr對結構與機械性質的影響 91
4.4.6 微量添加Sn對結構與機械性質的影響 95
4.4.7 微量添加W對結構與機械性質的影響 99
4.4.8 微量添加C對結構與機械性質的影響 103
4.4.9 微量添加元素對機械性質的綜合比較 107
4.5 均質化處理對Al15、Al20、Al25、Al30高熵合金的探討 110
4.5.1 均質化處理對結構與機械性質的影響 110
4.6 均質化處理對Ni30合金的探討 116
4.6.1 均質化處理對結構與機械性質的影響 116
4.7 時效處理對Al15、Al20合金的探討 119
4.7.1 時效處理時間對結構與機械性質的影響 119
4.8 利用VEC預測σ相的析出 129
4.8.1 VEC預測方法介紹 129
4.8.2 以VEC歸納本實驗數據 131
伍、 結 論 133
陸、 研究貢獻 137
柒、 建議未來研究方向 138
捌、 參考文獻 139

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