實驗室蘇穎奇學長對於鑄造態AlCoCrFeMoNi高熵合金雙相結構研究提升合金的硬度值與破壞韌性。發現此合金系統中，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元素則會促成σ相形成。
由於Ni含量較高的合金：Ni25及Ni30，具有FCC + σ相結構。可期望FCC相增加韌性及高溫強度，σ相可增加高溫強度，故本實驗選此兩合金且特別利用粉末冶金製程製作高熵合金，希望可以利用σ相細緻均勻地分布於FCC基地相中，達到σ相提升硬度，FCC相增加韌性及高溫強度的效果，以增加應用範圍。
首先選取高熵合金氣噴粉末並加入適量羰基鐵粉和黏結劑，再進行濕式球磨混合及冷壓錠。最後使用水平爐管，調節燒結溫度曲線及保護氣氛，成功燒結出高熵粉末冶金試片。
綜合觀察Ni25、Ni30合金之顯微結構及晶體結構，可以發現在富含Fe、Co、Ni的FCC灰色基地相中，有富Mo、Cr的白色σ相，另外有網狀分佈的斑馬紋結構包含黑色相及淺灰色相，黑色相為富含Ni、Al的BCC相；淺灰色相為富Fe、Cr、Mo的區域。顯示利用粉末冶金的方式，確實可以得到較為細緻的相分布情形。其硬度達HV 580且壓痕周圍皆不會出現裂痕，代表此合金具有足夠的韌性。且此合金中的σ相，使合金在高溫下不易軟化，具有高溫應用之潛力。

Ni25 and Ni30 high entropy alloys, which consist of FCC + σ phase, are selected. High entropy alloys are prepared by powder metallurgy in this study. It is hoped that the characteristics of powder metallurgy can be used to control the σ phase distribution in the FCC base phase uniformly. The hardness can be improved by the σ phase and the toughness can be maintained by the FCC phase.
First, the high entropy alloys powders are prepared by gas atomization. Then an appropriate amount of carbonyl iron powder and a binder are added, mixed by wet ball milling and followed by cold compaction. Finally, the green compact is sintered under protective atmosphere, and the high entropy alloys are successfully sintered.
By comprehensively observing the microstructure and crystal structure of Ni25 and Ni30 alloys, it can be found that the FCC gray phase is rich in Fe, Co and Ni, the white σ phase is rich in Mo and Cr, a zebra structure with intervened black phase (BCC phase rich in Ni and Al) and light gray phase (rich in Fe, Cr and Mo). The microstructure shows that the method of powder metallurgy can indeed obtain a fine phase distribution.
The hardness could be attained to HV 580 and no crack around the hardness indentation could be found, which means that the alloy has sufficient toughness. The σ phase lets the alloy resist softening and maintain its high temperature strength, These alloys have the potential for high temperature applications.

摘 要 I
Abstract III
誌 謝 V
目 錄 VII
圖目錄 XII
表目錄 XIX
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 粉末製備方式 15
2.4.1 粉末製備方式簡介 15
2.5 燒結方式及機制 21
2.5.1 固相燒結 21
2.5.2 液相燒結 25
2.5.3 燒結方式簡介 33
2.6 高熵合金 38
2.6.1 開發背景 38
2.6.2 高熵合金的特色 39
參、實驗方法 46
3.1 合金製備與實驗流程 46
3.1.1 合金選擇與製備 46
3.1.2 實驗流程 46
3.2 模擬相圖 49
3.3 粉末成型及燒結 50
3.3.1 水平球磨 50
3.3.2 生胚成型 51
3.3.3 燒結製程 52
3.4 性質分析與其它分析 54
3.4.1 X-ray繞射分析 54
3.4.2 微結構與EDS成分分析 55
3.4.3 密度量測與緻密度 55
3.4.4 硬度韌性量測 56
3.4.5 DTA熱分析 57
3.4.6 高溫硬度量測 57
3.4.7 Pin on disk磨耗測試 60
3.4.8 ImageJ影像分析 60
肆、結果與討論 61
4.1 原料粉末分析 61
4.1.1 微結構、橫截面微結構與晶體結構 62
4.1.2 Ni25、Ni30粉末的DTA分析 68
4.1.3 不同熱處理溫度之粉末橫截面微結構與晶體結構 70
4.1.4 模擬相圖討論及參考 73
4.2 不同含量的鐵粉添加與Ni30f粉末之燒結 75
4.2.1 燒結參數建立 75
4.2.2 XRD分析 77
4.2.3 微結構與EDS成分分析 79
4.2.4 機械性質比較 90
4.2.5 1300 C 1 h熱處理之探討 91
4.3 不同含量的鐵粉添加與Ni25粉末之燒結 92
4.3.1 燒結參數建立 92
4.3.2 XRD分析 94
4.3.3 微結構與EDS成分分析 97
4.3.4 機械性質 103
4.4 不同含量的鐵粉添加與Ni30粉末之燒結 104
4.4.1 燒結參數建立 104
4.4.2 XRD分析 106
4.4.3 微結構與EDS成分分析 108
4.4.4 機械性質 112
4.5 使用MIM binder與製程 113
4.5.1 實驗方法與燒結參數建立 113
4.5.2 XRD分析 116
4.5.3 微結構與EDS成分分析 118
4.5.4 機械性質比較 123
4.5.5 各相比例組成 124
4.5.6 微硬度測試及討論 127
4.5.7 高溫硬度量測 130
4.5.8 Pin on disk磨耗測試 131
伍、結論 132
陸、研究貢獻 134
柒、建議未來研究方向 134
捌、參考文獻 135

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