金屬材料在材料科學領域中的發展歷史悠久，且與人類生活緊密相關。但其累積至今豐厚的研究成果也造成近代金屬研究領域較缺乏大幅度的突破。過去十年內，一種新的合金系統「高熵合金」被提出並逐漸受到各界學者的重視，其特殊的機械性質與元素組成為合金材料的發展打開全新的領域。由於高熵合金的特殊組成規則顯然與傳統合金不同，目前大多針對高熵合金的實驗成果仍未能完整解釋高熵合金具有特殊機械性質的核心原理。本研究對一系列FCC合金包含傳統低熵合金NiW、中熵合金NiCrFe與高熵合金NiCrFeMnCo分別進行巨觀與微觀下機械行為與結構資訊的量測。巨觀部分包含基礎維氏硬度測量以及密度測量，微觀部分則是藉由奈米壓痕測試、臨場SEM微米柱壓應、臨場TEM奈米柱壓應觀察並分析不同亂度與三種晶體方向 (100)、(110)、(111) 之下單晶合金的機械行為變化，以高強度X光繞射分析高熵合金與傳統合金的微觀結構差異。結合上述巨觀與微觀實驗結果，與理論計算之合金資訊做相互參照分析，本實驗發現諸多高熵合金相對於傳統合金在變形行為上的顯著差異以及結構的明顯變化，進一步為探索高熵合金核心原理的未來研究方向提供重要的訊息。

Metal has always been a crucial part of human society with prestigious status in the field of material science development history. However the abundant research done on metal and alloy also resulted in the lack of marginal breakthrough in modern days. During last decade, a brand new alloying system called “High Entropy Alloys” (HEAs) was presented and gradually gaining attention from all associations, its special mechanical properties and element composition has dawned a new era of alloy materials. Due to apparent differences of formation rules between HEAs and traditional alloys, current researches toward HEAs are still far from successfully providing results to explain the core effect and compositional theory of HEAs. This research was done on a series of FCC alloys consists of traditional low-entropy NiW alloys, medium-entropy alloy NiCrFe and HEA NiCrFeMnCo by conducting mechanical and structural experiment respectively in both macro and micro scales. Macro scale experiments included Vickers hardness and density measurement. Micro scale experiments included nano indentation, in-situ SEM micro pillar compression and in-situ TEM nano pillar compression, respectively performed on (100), (110) and (111) crystal planes of alloys with different entropy status. Micro scale crystal structure differences between traditional alloys and HEAs was obtained via high intensity X-ray diffraction. By analyzing mentioned experiment results with theoretical information, we found numerous distinct differences in both deformation behavior and crystal structure between traditional alloys and HEAs, providing further insight for future study of HEA’s core effect and compositional theory.

誌謝 I
摘要 III
Abstract IV
目錄 V
圖目錄 IX
表目錄 XV
壹、前言 1
貳、文獻回顧 3
2-1高熵合金 3
2-1-1高熵合金之發展 3
2-1-2高熵合金核心效應 5
2-1-3高熵合金之特性與應用 7
2-1-4高熵合金之機械行為研究 11
2-2材料機械行為及其影響因素 16
2-2-1鍵結 16
2-2-2晶體結構 19
2-2-3元素成分比例 21
2-2-4固溶與摻雜 23
2-2-5異向性 25
2-2-6微結構與邊界影響因素 28
2-2-7尺寸效應 30
2-3結構扭曲及其分析 32
2-3-1結構扭曲 32
2-3-2結構扭曲之理論計算 37
2-3-3結構扭曲之實驗分析 39
2-4奈米尺度機械行為分析 42
2-4-1奈米壓痕測試 (Nanoindentation) 42
2-4-2臨場掃描式電子顯微鏡 (In-situ SEM) 分析 44
2-4-3臨場穿透式電子顯微鏡 (In-situ TEM) 分析 47
2-5研究目的 49
參、實驗步驟 50
3-1實驗規劃 50
3-2實驗步驟 51
3-2-1低熵、中熵、高熵合金試片製備 51
3-2-2成分分析與理論計算 52
3-2-3巨觀定性分析 52
3-2-4晶體結構資料分析 53
3-2-5晶粒方向鑑定 55
3-2-6微觀機械分析 57
3-2-7聚焦離子束 (FIB) 臨場試片製備 59
3-2-8奈米壓痕結構變形分析 62
3-2-9臨場SEM壓縮測試 (In-situ SEM Compression) 64
3-2-10臨場TEM壓縮測試 (In-situ TEM Compression) 66
肆、結果與討論 68
4-1成分鑑定與巨觀定性分析 68
4-1-1成分鑑定 68
4-1-2材料密度 68
4-1-3維氏硬度 68
4-2結構扭曲與X光繞射分析 73
4-2-1理論結構扭曲計算分析 73
4-2-2 X光繞射分析 75
4-3奈米壓痕測試分析 79
4-3-1 彈性模數 (Elastic Modulus) 79
4-3-2 奈米硬度 (Nano Hardness) 80
4-3-3 位移突進距離 (Displacement Burst Range) 80
4-4奈米壓痕截面結構分析 87
4-4-1低熵至高熵合金之比較 87
4-4-2 (100)、(110)、(111) 方向之比較 88
4-5臨場SEM壓縮測試分析 99
4-5-1低熵至高熵合金之比較 99
4-5-2 [100]、[110]、[111] 方向之比較 99
4-6臨場TEM壓縮測試分析 105
4-6-1傳統低熵合金分析 105
4-6-2中熵合金分析 105
4-6-3高熵合金分析 106
4-6-4低熵至高熵合金之比較 107
4-7 變形機制綜合比較分析 111
伍、結論 114
陸、參考文獻 115

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