AZ31 鎂合金滾軋板材經由等徑轉角擠型(Equal Channel Angular Extrusion, ECAE)將晶粒細化至0.46μm 與0.37μm 且具有強烈織構(Texture)組織，發現其有優良之低溫超塑性行為。本研究之變形溫度範圍在75~125℃，應變速率在1x10-5 /s 至2x10-3 /s。研究結果發現，晶粒尺寸為0.37μm時，試片在100℃(~0.4Tm)下，elongation 可達~ 441%。由微觀表面觀察及m值(strain rate sensitivity)的測量，得之低溫超塑性的發生乃因有晶界滑移的發生。本研究亦顯示，即使試片織構不利差排滑移，晶界滑移仍可使試片有優良之低溫超塑性。

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目錄.......................................................................................................................... Ⅰ
表目錄...................................................................................................................... Ⅲ
圖目錄...................................................................................................................... Ⅳ
摘要.......................................................................................................................... Ⅶ
一、前言.................................................................................................................. 1
二、文獻回顧.......................................................................................................... 2
2-1 鎂合金之變形機制 ..................................................................................... 2
2-1-1 低溫下的變形機制: 滑移系統與變形雙晶 .................................. 2
2-1-2 高溫下的變形機制: 動態再結晶 .................................................. 3
2-2 材料超塑性行為 ......................................................................................... 4
2-3 鎂合金低溫超塑性回顧 ............................................................................. 7
三、研究目的.......................................................................................................... 15
四、實驗方法.......................................................................................................... 16
4-1 材料與ECAE 製成 .................................................................................... 16
4-2 拉伸試片製備 ............................................................................................ 17
4-3 拉伸試驗 .................................................................................................... 17
4-3-1 應力-應變曲線之測量.................................................................... 17
4-3-2 m 值(strain rate sensitivity)之測量 ................................................. 18
4-4 掃描式電子顯微鏡試片製作 .................................................................... 18
五、實驗結果.......................................................................................................... 20
5-1 試片外觀 .................................................................................................... 20
5-2 應力-應變曲線 ........................................................................................... 20
5-2-1 grain size: 0.46μm ........................................................................... 20
5-2-2 grain size: 0.37μm ......................................................................... 22
5-3 m 值(strain rate sensitivity) ...................................................................... 24
5-3-1 grain size: 0.46μm ........................................................................... 24
5-3-2 grain size: 0.37μm ......................................................................... 25
5-4 變形之活化能(Q) ....................................................................................... 25
六、討論.................................................................................................................. 27
七、結論.................................................................................................................. 31
八、參考文獻.......................................................................................................... 32
表.............................................................................................................................. 34
圖.............................................................................................................................. 40

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