臺灣博碩士論文加值系統

在200℃，10-3s-1應變率的條件下，以壓縮方式對於擠型之AZ31鎂合金進行變形，研究其顯微組織演化過程。因為擠型材集合組織之特色，試片首先以拉伸雙晶方式變形，繼而以壓縮雙晶變形。在此變形期間，伴隨著晶界產生鋸齒狀之動態再結晶的進行。動態再結晶除了可在晶界形成也可生長於雙晶界上。隨著壓縮量之增加，動態再結晶亦持續增生，試片因動態再結晶導致之變形集中現象，形成了剪切帶(Shear Zone)。最後在動態再結晶聚集處產生裂縫，在高變形量下因此而斷裂。
從動態再結晶開始生長到剪切帶形成期間，動態再結晶晶粒之晶向開始時與原始晶粒晶向相近，之後的動態再結晶晶粒，有著漸漸向與受力軸呈45度角旋轉的趨勢。剪切帶中的原始晶粒之晶向亦有旋轉之傾向。

目錄
一、 前言…................................................................................................................1
二、 文獻回顧…........................................................................................................2
2-1鎂與鎂合金的變形機制.............................................................................2
2-1.1低溫下的變形機制：滑移系統.................................................................2
2-1.2低溫下的變形機制：變形雙晶.................................................................2
2-1.3高溫下的變形機制：動態再結晶.............................................................3
2-1.4鎂合金與集合組織之關係.......................................................................4
2-2鎂合金的動態再結晶機制..........................................................................5
2-2.1連續動態再結晶：轉動動態再結晶.........................................................6
2-2.2不連續動態再結晶：晶界移動式動態再結晶.........................................6
2-2.3動態再結晶的形成機制探討...................................................................7
2-2.4動態再結晶的形成過程...........................................................................8
2-2.5動態再結晶的晶向特性...........................................................................9
2-2.6在雙晶上的動態再結晶...........................................................................9
2-3變形集中現象..............................................................................................9
2-3.1應變集中現象...........................................................................................9
2-3.2應變集中特色.........................................................................................10

三、 研究目的......................................................................................................... 12

四、 實驗方法..........................................................................................................13
4-1實驗流程....................................................................................................13
4-2壓縮試片製作............................................................................................13
4-3壓縮試驗....................................................................................................13
4-4應力應變分析............................................................................................14
4-5金相試片製作............................................................................................14
4-6光學顯微鏡與掃描式電子顯微鏡觀察....................................................14
4-7背散式電子繞射分析與其試片製作........................................................15

五、 實驗結果..........................................................................................................17
5-1試片外觀....................................................................................................17
5-2微結構觀察................................................................................................17
5-2.1微觀組織演化過程.................................................................................17
5-2.2變形集中帶觀察….................................................................................18
5-2.3晶界旁組織演化過程….........................................................................18
5-2.4應力應變曲線與演化過程.....................................................................18
5-3 EBSD結晶方向分析.................................................................................18
5-3.1初始材料集合組織.................................................................................19
5-3.2動態再結晶晶向分析.............................................................................19
5-3.3變形集中之EBSD分析..........................................................................19

六、 討論..................................................................................................................21
6-1集合組織與微結構變化............................................................................21
6-2顯微組織演化與討論................................................................................21
6-3變形集中討論............................................................................................22

七、 結論..................................................................................................................25

八、 參考文獻..........................................................................................................26

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