臺灣博碩士論文加值系統

本實驗藉由摩擦攪拌製程將不同重量百分比組成的鋁及鎂粉
末，並利用不同工作頭尺寸(凸銷和肩部)或轉速來製作成晶粒範圍
0.5μm~1.5μm 不同晶粒大小的鋁鎂合金。之後我們利用拉伸測試
(1x10-1 mm/s、1x10-3 mm/s、1x10-5mm/s)來瞭解機械性質，以及利用
掃描式顯微鏡(SEM)和X-ray 繞射儀來觀察微觀結構和組成相，此外
也針對此材料變形演化作探討。
本研究中可以很清楚的發現藉由摩擦攪拌製程添加鎂固溶於鋁
基材時可以同時提升強度和均勻延展性，添加越多的鎂含量效果越明
顯。在實驗中發現許多微小的滑移帶提供良好的加工硬化率，所以擁
有優異的均勻延展性。此外，鋁鎂合金拉伸曲線上經常出現抖動情
形，此為固溶鎂原子與移動差排產生交互作用，文獻中稱為動態性變
時效。在此我們將利用應變速率和鎂含量的改變，對於抖動型態的影
響且對於抖動型態是否會影響機械性質來作探討。

Al-Mg solid solution alloys of various grain sizes were prepared by
friction stir processing (FSP). The mechanical properties and
micro-structure evolution were studied. The results show that the
mechanical properties including tensile strength and ductility are
improved by increasing Mg weight fraction. The homogeneous
deformation is enhanced by fined slip bands within the grains. On the
other hand, Dynamic strain aging or serrated flow stress has been wildly
investigated in Al-Mg alloys. Effects of strain rate and magnesium
content on dynamic strain aging are also discussed.

總目錄
中文摘要......................................................................................................................... I
英文摘要........................................................................................................................ II
總目錄 ........................................................................................................................ III
表目錄 .........................................................................................................................V
圖目錄 ....................................................................................................................... VI
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.......................................................................................................... 5
2-1 摩擦攪拌焊接(Friction Stir Welding，FSW)................................................. 5
2.1.1 摩擦攪拌焊接原理............................................................................... 5
2.1.2 摩擦攪拌製程(Friction Stir Process，FSP) ......................................... 5
2.2 Al-Mg 合金基本特性 ...................................................................................... 6
2.3 Al-Mg 合金的機械性質 .................................................................................. 6
2.3.1 固溶強化............................................................................................... 7
2.3.2 加工硬化行為....................................................................................... 8
2.3.3 細晶強化............................................................................................... 9
2.4 超細晶粒材料的延展性................................................................................ 10
2.4.1 利用不同大小的晶粒混合(bimodal grain size) ................................ 10
2.4.2 應變速率控制延展性......................................................................... 11
2.4.3 添加強化相顆粒或均勻析出相......................................................... 12
2.4.4 降低疊差能(stacking fault energy) .................................................... 12
2.5 動態應變時效(Dynamic Strain Ageing) ....................................................... 13
第三章實驗方法........................................................................................................ 15
3.1 實驗材料成分和製備.................................................................................... 15
3.1.1 微米級鋁粉及鎂粉............................................................................. 15
3.1.2 實驗塊材製作..................................................................................... 15
3.2 摩擦攪拌製程............................................................................................... 16
3.2.1 工具頭及夾具..................................................................................... 16
3.2.2 摩擦攪拌製程機器簡介.................................................................... 16
3.2.3 摩擦攪拌製程步驟............................................................................ 16
3.3 巨觀結構與顯微組織分析............................................................................ 16
3.3.1 X-Ray 繞射分析 ................................................................................. 16
IV
3.3.2 掃描電子顯微鏡觀察及分析............................................................. 17
3.4 機械性質量測與分析.................................................................................... 17
3.4.1 拉伸測試............................................................................................. 17
第四章實驗結果與討論.............................................................................................. 18
4.1 繞射分析........................................................................................................ 18
4.2 晶粒尺寸分析................................................................................................ 18
4.3 機械性質量測................................................................................................ 19
4.3.1 應變應力曲線..................................................................................... 19
4.3.2 晶粒尺寸及鎂含量與加工硬化率的關係......................................... 20
4.3.3 不同合金系統比較............................................................................. 22
4.3.4 應變速率對於延展性的綜合影響..................................................... 24
4.4 Portevin-Le Chatelier (PLC)效應特徵 .......................................................... 26
第五章結論................................................................................................................ 29
第六章參考文獻........................................................................................................ 31
表 ....................................................................................................................... 36
圖 ....................................................................................................................... 44

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