臺灣博碩士論文加值系統

實驗利用不同的製程參數，改變超細晶AA3003鋁錳合金的微結構，以及合金元素的固溶/析出量，並討論其影響。實驗利用ECAE施以大量的應變量，使AA3003鋁合金的晶粒細化。
隨著ECAE的應變量增加，晶粒逐漸的被細化成更小的次晶粒，AA3003的拉伸強度以及加工硬化率也都有明顯的提升。在ECAE擠製前，降低均質化溫度，則使材料有較多的二次相顆粒殘留，並且提升擠製後的拉伸強度，以及加工硬化率。而擠製後的材料，隨著後續退火溫度及時間的提升，微結構逐漸改變，且次晶粒逐漸長大，使得材料的強度也隨之下降，並且產生四種不同的拉伸變形行為。此外，在超細晶AA3003的退火行為中，有退火硬化的現象發生，其硬化程度又以高溫均質化的材料較為明顯。 超細晶AA3003鋁合金的應變速率敏感值(m)，受到ECAE的加工應變量不同，以及均質化溫度所影響。當ECAE加工應變量增加時，m也隨之提升，但m值仍小於低溫均質化處理後的材料。

表目錄 ....................................................................................................... iv
圖目錄 ......................................................................................................... v
一、前言 ..................................................................................................... 1
二、文獻回顧 ............................................................................................ 2
2-1 AA3003鋁合金............................................................................ 2
2-1-1 AA 3003鋁合金的析出物 ............................................... 3
2-2 等徑轉角擠型(equal channel angular extrusion, ECAE) ...... 5
2-2-1 等徑轉角擠型之原理 ...................................................... 5
2-2-2 ECAE的應變量............................................................... 6
2-3 超細晶金屬之機械性質 ............................................................. 7
2-3-1 超細晶金屬的強度 .......................................................... 8
2-3-2 超細晶的降伏下降(yield drop)現象 ............................. 9
2-3-3 超細晶金屬的延展性 .................................................... 10
2-3-4 超性晶材料的應變速率敏感度 ................................... 13
2-3-5 超細晶金屬的晶界特性 ................................................ 15
2-4 添加固溶合金元素的影響 ....................................................... 17
三、研究目的 .......................................................................................... 19
四、實驗方法 .......................................................................................... 20
4-1 實驗材料 ................................................................................... 21
4-2 均質化處理 (homogenization) ............................................... 21
4-3 等徑轉角擠型 (ECAE) ........................................................... 22
4-4 退火處理 (annealing) .............................................................. 22
4-5 微硬度測詴 (microhardness test) .......................................... 23
4-6 拉伸測詴 (tensile test) ............................................................ 24
4-7 微結構分析 (microstructure analysis) .................................. 25
五、實驗結果 .......................................................................................... 26
5-1 ECAE擠製後的微結構 ............................................................ 27
5-2 ECAE擠製AA3003 鋁合金的退火行為 ............................... 29
5-2-1 退火軟化曲線 ................................................................ 29
5-2-2 退火溫度造成的微結構變化 ....................................... 30
5-2-3 退火時間造成的微結構變化 ....................................... 31
5-3 超細晶AA3003鋁合金的拉伸變形行為 ............................... 32
5-3-1 ECAE擠製後的拉伸機械性質 .................................... 32
5-3-2 退火處理後的拉伸機械性質 ....................................... 34
5-3-3 低應變速率下的拉伸變形行為 ................................... 37
5-3-4 應變速率改變(strain rate jump)測詴 ......................... 38
5-3-5 拉伸後的表面變形與微結構 ....................................... 39
5-4 實驗結果總論 ........................................................................... 41
六、討論 ................................................................................................... 43
6-1 晶粒尺寸與降伏強度之關係 ................................................... 43
6-2 超細晶的降伏下降現象 ........................................................... 45
6-3 ECAE應變量對於超細晶AA3003的拉伸強度影響 ............ 47
6-4 均質化處理溫度對於超細晶AA3003的拉伸強度影響 ....... 48
6-5 超細晶AA3003的退火硬化現象 ........................................... 49
6-6 超細晶AA3003的應變速率敏感度 ....................................... 51
七、結論 ................................................................................................... 55
參考文獻 ................................................................................................... 57

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