以五元或五元以上等莫耳元素組成之高熵合金設計概念已受國內外矚目，漸漸成為學術界爭相研究的目標。從2010年美國空軍實驗室開始發表一系列耐火高熵合金，第一組 NbTaMoW、VNbTaMoW，具有優異的高溫壓縮強度 (1600 °C 時為 477 MPa)，缺點為室溫延性不佳且密度過高，不利於實際應用，隨後又發表第二組耐火高熵合金 HfNbTaTiZr，其室溫壓縮塑性應變量大於50%，具有很好的延性，而在之後研究中，也逐漸提升其在高溫上的使用程度，增加此款合金在航太材料上未來使用的可能性。
本實驗室亦對耐火高熵合金系統做了多年的研究，在中高溫段的合金系統與極高溫段的合金運用領域，在機械性質與高溫強度有了極大的突破，但在抗高溫氧化性質上仍然受到限制，並且合金在中高溫區段會產生氧化物粉末嚴重剝落之蟲咬現象，限制其應用性，並且無法以合金化的方式來進行改良，因其改善效果有限並會對本身合金的基本性質造成影響，因此在合金表面鍍製抗氧化層為較可行之解決方法。
在本次研究中，以張政泓學長所開發改良之 M 合金作為基材，雖然該合金在其應用溫度 700 °C、800 °C、900 °C 氧化 24 小時內即造成嚴重的破壞，但本研究利用新開發的處理製程，可使合金在 700 °C、800 °C、900 °C 氧化經歷 100 小時仍未產生破壞，大幅提升其應用性。此外，本研究亦對原合金及表面處理後的氧化行為及微結構做深入探討，並瞭解其改進的機制。

High-entropy alloys (HEAs) are defined as the alloys composed of at least five principle elements. Among them, refractory high entropy alloys (RHEAs) are promising candidates for aerospace structural materials due to their superb high-temperature strength and great mechanical property. However, the poor oxidation resistance, mainly owing to the formation of non-protective oxide scale has severely limited the capabilities of these alloys in applications. Furthermore, an accelerated oxidation or more specifically, pesting, in the temperature range of 700-800 °C has been observed for RHEAs, where the oxidation leads the material to catastrophically disintegrate into powders. To improve their oxidation resistance, alloying elements such as Al, Cr, Si in RHEAs has been studied, whereas the improvements are extremely restricted as these alloying elements may lead to deterioration of mechanical property of the alloys. As the result, the protective coating is necessary for their practical application in high temperature.
In this study, various surface treatments are developed for M alloy. The coated specimens have been verified to possess much lower mass gain than the base alloy after exposure of 100 hours at 700, 800 and 900 °C. This significantly improves the oxidation resistance amd let refractory high entropy alloys have potential applications at high tempeartures. In addition, the oxidation behavior and microstructure are studied and the mechanism of oxidation improvement is revealed.

摘要 I
Abstract III
致謝 V
目錄 X
圖目錄 XVII
表目錄 XXXI
壹、 前言 1
貳、 文獻回顧 3
2.1 鎳基超合金發展與應用 3
2.2 耐火合金 5
2.2.1 鈮合金[34] 7
2.3 高熵合金[22] 9
2.3.1 開發背景 9
2.3.2 高熵合金的特性 10
2.3.3 耐火高熵合金 13
2.3.3.1 W-Nb-Ta-Mo, W-Nb-Ta-Mo-V[43, 44] 13
2.3.3.2 Hf-Nb-Ta-Ti-Zr[45, 46] 17
2.3.3.3 NbCrMo0.5Ta0.5TiZr[47] 25
2.3.3.4 CrNbTiVZr[48, 49] 27
2.3.3.5 鋁添加耐火高熵合金[50] 29
2.4 表面處理[51] 31
2.4.1 表面處理之機制[51, 52] 31
2.4.2 表面處理於耐火合金之應用 33
2.4.3 表面處理於高熵合金之應用 40
2.5 本論文研究目的 43
參、 實驗步驟 44
3.1 實驗設計 44
3.2 實驗流程 44
3.2.1 實驗流程圖 44
3.2.2 真空電弧熔煉 44
3.2.3 鍍層製備流程 45
3.2.3.1 基材預處理 46
3.2.3.2 粉末預處理 46
3.2.3.3 表面處理 A、B 流程 46
3.2.4 氧化前試片預處理 47
3.2.4.1 表面處理 C 47
3.2.4.2 表面處理 D 47
3.2.5 氧化增重試驗 47
3.2.6 晶體結構與微結構分析 49
3.2.6.1 XRD 繞射分析 49
3.2.6.2 電子顯微鏡 49
肆、 結果與討論 50
4.1 純合金高溫氧化討論 50
4.1.1 氧化增重數據分析 52
4.1.2 700 C 氧化層分析 59
4.1.2.1 氧化層 XRD 分析 59
4.1.2.2 氧化層微結構 60
4.1.3 800 C 氧化層分析 63
4.1.3.1 氧化層 XRD 分析 63
4.1.3.2 氧化層微結構 64
4.1.4 900 C 氧化層分析 67
4.1.4.1 氧化層 XRD 分析 67
4.1.4.2 氧化層微結構 68
4.2 表面處理 A 參數調控與高溫氧化討論 72
4.2.1 表面處理 A 參數調控 72
4.2.1.1 鍍層 XRD 分析 72
4.2.1.2 鍍層微結構 74
4.2.2 表面處理 A 試片氧化增重數據分析 81
4.2.3 表面處理 A 試片 700 C 氧化層分析 88
4.2.3.1 氧化層 XRD 分析 88
4.2.3.2 氧化層微結構 89
4.2.4 表面處理 A 試片 800 C 氧化層分析 93
4.2.4.1 氧化層 XRD 分析 93
4.2.4.2 氧化層微結構 94
4.2.5 表面處理 A 試片 900 C 氧化層分析 98
4.2.5.1 氧化層 XRD 分析 98
4.2.5.2 氧化層微結構 100
4.2.6 試片失效原因探討 109
4.3 表面處理 B 參數調控與高溫氧化討論 111
4.3.1 表面處理 B 參數調控 111
4.3.1.1 參數甲調控 111
4.3.1.2 參數乙調控 117
4.3.2 表面處理 B 試片氧化增重數據分析 120
4.3.3 表面處理 B 試片 700 C 氧化層分析 127
4.3.3.1 氧化層 XRD 分析 127
4.3.3.2 氧化層微結構 128
4.3.4 表面處理 B 試片 800 C 氧化層分析 131
4.3.4.1 氧化層 XRD 分析 131
4.3.4.2 氧化層微結構 132
4.3.5 表面處理 B 試片 900 C 氧化層分析 136
4.3.5.1 氧化層 XRD 分析 136
4.3.5.2 氧化層微結構 137
4.4 表面處理 C 參數調控與高溫氧化討論 141
4.4.1 表面處理 C 參數調控 141
4.4.2 表面處理 C 試片氧化增重數據分析 146
4.4.3 表面處理 C 試片 700 C氧化層分析 153
4.4.3.1 氧化層 XRD 分析 153
4.4.3.2 氧化層微結構 154
4.4.4 表面處理 C 試片 800 C氧化層分析 160
4.4.4.1 氧化層 XRD 分析 160
4.4.4.2 氧化層微結構 161
4.4.5 表面處理 C 試片 900 C氧化層分析 168
4.4.5.1 氧化層 XRD 分析 168
4.4.5.2 氧化層微結構 169
4.5 表面處理 D 參數調控與高溫氧化討論 173
4.5.1 表面處理 D 處理參數調控 173
4.5.1.1 玻璃基板成膜性測試 173
4.5.1.2 表面處理 D 微結構 176
4.5.2 表面處理 D 試片氧化增重數據分析 181
4.5.2.1 長時間氧化增重測試 181
4.5.2.2 試片氧化增重結果 183
4.5.3 表面處理 D 試片 700 C氧化層分析 189
4.5.3.1 氧化層 XRD 分析 189
4.5.3.2 氧化層微結構 190
4.5.4 表面處理 D 試片 800 C氧化層分析 194
4.5.4.1 氧化層 XRD 分析 194
4.5.4.2 氧化層微結構 195
4.5.5 表面處理 D 試片 900 C氧化層分析 199
4.5.5.1 氧化層 XRD 分析 199
4.5.5.2 氧化層微結構 200
伍、 結論 206
陸、 本研究貢獻及未來工作建議 210
6.1 本研究貢獻 210
6.2 未來工作建議 212
柒、 參考文獻 213

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