本實驗藉由摩擦攪拌製程研究Al-5Zn-1Mg及Al-5Zn合金的機械性質，探討添加1wt%鎂前後，不同晶粒尺寸及拉伸速率所呈現的機械強度和塑性變形機制為何。
在不同工具頭尺寸及轉速下，Al-5Zn-1Mg及Al-5Zn分別製作出三種平均晶粒尺寸不同樣本，Al-5Zn-1Mg為2.47 μm、1.24 μm及0.91 μm，而Al-5Zn則是1.50 μm、1.00 μm及0.50 μm。前述樣本分別以3種不同拉伸速率(10-3 s-1、10-4 s-1及10-5 s-1)進行拉伸試驗，總計得到18組的機械性質實驗數據。
本研究中可以很清楚看到添加1 wt%鎂後，降伏強度、最大拉伸強度及均勻延展性皆明顯提升。此外藉由應變速率敏感係數等數據分析顯示，Al-5Zn所展現的反Hall-Petch關係趨勢在Al-5Zn-1Mg皆看不到，暗示了鎂的添加降低了鋅的效應。

Friction stir processing method was employed to study mechanical properties of Al-5Zn-1Mg and Al-5Zn alloy with various parameters including grain size and tensile strain rate.
Average grain size for Al-5Zn-1Mg alloy are 2.47 μm, 1.24 μm, and 0.91 μm. Each sample was pulled in tension at strain rate of 10-3 s-1, 10-4 s-1, and 10-5 s-1.
In this study, we found that 1wt% magnesium to Al-5Zn alloy can improve yield strength, Ultimate tensile strength and uniform elongation. Also strain rate sensitivity coefficient analysis showed that the inverse Hall-Petch relationship trends exhibited in Al-5Zn did not discovered in Al-5Zn-1Mg. It suggests that addition of magnesium to reduce the effect of zinc.

第 一 章 前言........................................................................................1
1.1 研究背景說明...........................................................................1
1.2 研究動機與目的.......................................................................3
第 二 章 文獻回顧 ..............................................................................4
2.1 摩擦攪拌製程用於製作超細晶材料.......................................4
2.1.1 摩擦攪拌製程..................................................................4
2.1.2 摩擦攪拌製程晶粒尺寸..................................................5
2.2 金屬基複合材料的機械性質...................................................5
2.2.1 加工硬化..........................................................................5
2.2.2 固溶強化..........................................................................6
2.2.3 細晶強化..........................................................................6
2.2.4 Hall-Petch曲線偏差相關理論….....................................7
2.2.5 應變速率敏感係數..........................................................9
2.3 Al-Zn合金的基本性質.........................................................10
第 三 章 實驗方法 ............................................................................11
3.1 實驗材料成分與製備.............................................................11
3.1.1 鋁粉、鋅粉與鎂粉..........................................................11
3.1.2 實驗塊材製作................................................................11
3.2 摩擦攪拌製程.........................................................................12
3.2.1 工具頭與夾具................................................................12
3.2.2 摩擦攪拌製程機器簡介................................................12
3.2.3 試片代號........................................................................13
3.2.4 摩擦攪拌製程步驟........................................................13
3.3 微觀組織分析.........................................................................14
3.3.1 掃描式電子顯微鏡分析試片表面形貌及成份............14
3.3.2 X光繞射分析 ..............................................................14
3.3.3 電子微探儀(EPMA)定量分析.......................................15
3.3.4 背向散射電子繞射(EBSD)分析....................................15
3.4 機械性質測量.........................................................................16
3.4.1 拉伸試驗........................................................................16
第 四 章 實驗結果與討論..................................................................17
4.1 晶粒大小.................................................................................17
4.2 表面形貌及成分分析.............................................................18
4.3 X光繞射分析.........................................................................19
4.4 電子微探儀定量分析結果.....................................................19
4.5 拉伸性質量測.........................................................................20
4.5.1 應力應變曲線................................................................20
4.6 m值變動與拉伸速率及晶粒尺寸關係..................................22
第 五 章 結論......................................................................................23
參考文獻..................................................................................................24
表..............................................................................................................28
圖..............................................................................................................36

表 目 錄
表 2-1 不同摩擦攪拌銲接/製程下攪拌區內晶粒的變化的比較。.....................28
表 2-2 超細晶產製方式的比較。[19]....................................................................30
表 3-1 工具頭規格。...............................................................................................31
表 4-1 FSP 參數與晶粒粒徑大小關係。..............................................................32
表 4-2 EPMA 試片定量分析表。(Al-5Zn數據由[16]提供)................................33
表 4-3 不同試片拉伸曲線中不同晶粒大小及拉伸速度其機械性質。(Al-5Zn數據由[16]提供) ............................................................................................34
表 4-4 Al-5Zn及Al-5Zn-1Mg拉伸曲線中不同拉伸速率其m值。(Al-5Zn數據由[16]提供).....................................................................................................35
表 4-5 633-700 rpm試片之EDS點分析成分表。..........................................35

圖 目 錄
圖 2-1 Al-Zn 合金之二元平衡相圖。...................................................................36
圖 2-2 較強交互滑移發生於晶界部分圖示。.......................................................36
圖 2-3 多晶材料塑性變形的順序圖示。(a)局部塑性變形(microyielding)開始產生於晶界處，於該處發生加工硬化現象; (b)差排逐漸堆積於晶界處; (c)表示該作用加劇，開始強化試片整體強度; (d)應力於差排處集中; (e)差排堆積於晶界附近，使該區域應力上升; (f)應力上升擴大至整體晶粒，整體塑性變形因而發生.......................................................................37
圖 2-4 多晶材料中晶質部分與晶界(grain boundary,the triple line and the quadruplenode)所佔體積百分比與晶粒尺寸之關係圖。晶界厚度假設為1 nm[30]。.......................................................................................................38
圖 2-5 Ashby–Verall 機制:晶界滑移發生時相伴發生之臨近晶粒之間的原子塑性流動圖示，(a)原本相互緊靠的四個晶粒; (b)晶粒端點彼此產生輻合現象; (c)晶粒之間相對位置產生變化[34]。.........................................39
圖 2-6 晶界滑移示意圖。(a)晶界滑移在多晶系統中的圖示; (b)晶界滑移的途徑;(c)Raj and Ashby 所提出之理想晶界形狀(符合sin 函數) 及(d)由於拉伸量增加導致波高(h)減少[5]。.............................................................40
圖 2-7 銅金屬在不同拉伸速率下之Hall-Petch 關係圖，應力數值對應於為伸長率為0.2....................................................................................................41
圖 3-1 粉末成型機。...............................................................................................42
圖 3-2 粉末成型使用之夾具。...............................................................................42
圖 3-3 摩擦攪拌製程工具頭。...............................................................................43
圖 3-4 摩擦攪拌製程使用之夾具。.......................................................................43
圖 3-5 由銑床改裝之摩擦攪拌製程機。...............................................................44
圖 3-6 面板控制鈕號說明。...................................................................................44
圖 3-7 拉伸試片規格。...........................................................................................45
圖 3-8 實驗步驟流程。...........................................................................................45
圖 4-1 1666-1500rpm試片攪拌之後之EBSD晶粒尺寸分佈圖，平均尺寸為2.47± 1.83μm。.....................................................................................................46
圖 4-2 833-700rpm試片攪拌之後之EBSD晶粒尺寸分佈圖，平均尺寸為1.24 ± 0.52μm。.....................................................................................................46
圖 4-3 633-700rpm試片攪拌之後之EBSD晶粒尺寸分佈圖，平均尺寸為0.91 ± 0.48μm。.....................................................................................................47
圖 4-4 1666-1500rpm試片攪拌之後之5000倍SEM影像圖。由上至下分別為(a)SEI影像；(b)BEI影像。............................................................................48
圖 4-5 833-700rpm試片攪拌之後之5000倍SEM影像圖。由上至下分別為(a)SEI影像；(b)BEI影像。......................................................................................49
圖 4-6 633-700rpm試片攪拌之後之5000倍SEM影像圖。由上至下分別為(a)SEI影像；(b)BEI影像。......................................................................................50
圖 4-7 633-700rpm試片經ion-polisher之5000倍SEM影像圖。由上至下分別為(a)SEI影像；(b)BEI影像。........................................................................51
圖 4-8 633-700rpm試片之EDS點分析5000倍SEM影像示意圖。.................52
圖 4-9 833-1500rpm試片經ion-polisher之10000倍SEM影像圖。可以明顯看出細小亮點的析出物分佈在grain boundary上。由上至下分別為(a)SEI影像；(b)BEI影像。......................................................................................53
圖 4-10 (a)不同製程的Al-5Zn-1Mg鋁合金經FSP前後之X光繞射圖；(b)鋁合金經FSP製程後，在高角度下之Al(420)繞射峰偏移量。.............................54
圖 4-11 (a)不同製程的Al-5Zn-1Mg鋁合金經FSP後之X光繞射圖；(b) 7075鋁合金的η(MgZn2)繞射波峰圖，經對比確認後本實驗試片並無出現η(MgZn2)的繞射波峰。...............................................................................................55
圖 4-12 晶粒尺寸為 (a)0.91μm、(b) 1.24μm、(c) 2.47μm的Al-5Zn-1Mg試片之三種拉伸速率的工程應力對工程應變曲線圖。...........................................56
圖 4-13 拉伸速率為 (a)10-3s-1、(b)10-4s-1、(b)10-5s-1的Al-5Zn-1Mg試片之三種晶粒尺寸的工程應力對工程應變曲線圖。...................................................57
圖 4-14 晶粒尺寸為 (a) 0.5μm、(b) 1.0μm、(c) 1.5μm的Al-5Zn試片之三種拉伸速率的工程應力對工程應變曲線圖。[16]...........................................58
圖 4-15 拉伸速率為 (a)10-3s-1、(b)10-4s-1、(c)10-5s-1的Al-5Zn試片之三種晶粒尺寸的工程應力對工程應變曲線圖。[16]...................................................59
圖 4-16 不同鎂含量在不同晶粒大小下的降伏應力及抗拉強度，應變速率1x10-3s-1。(Al-5Zn數據由[16]所提供)........................................................60
圖 4-17 不同鎂含量在不同晶粒大小下的均勻延展性及總伸長量，應變速率1x10-3s-1。(Al-5Zn數據由[16]所提供)........................................................60
圖 4-18 不同鎂含量在不同晶粒大小下的降伏應力及抗拉強度，應變速率1x10-4s-1。(Al-5Zn數據由[16]所提供)........................................................61
圖 4-19 不同鎂含量在不同晶粒大小下的均勻延展性及總伸長量，應變速率1x10-4s-1。(Al-5Zn數據由[16]所提供)........................................................61
圖 4-20 不同鎂含量在不同晶粒大小下的降伏應力及抗拉強度，應變速率1x10-5s-1。(Al-5Zn數據由[16]所提供)........................................................62
圖 4-21 不同鎂含量在不同晶粒大小下的均勻延展性及總伸長量，應變速率1x10-5s-1。(Al-5Zn數據由[16]所提供)........................................................62

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