臺灣博碩士論文加值系統

在不同變形量下，晶界對其巨觀的非均勻性變形的影響遠小於晶體內在的性質(intrinsic effect)，如晶體方向(texture)與外在的性質(extrinsic effect)，如摩擦力等。然而，要對非均勻性的變形進行系統性之探討，就必須從這兩方面著手，先前之文獻已經對晶體方向的影響做了徹底的研究，在此本研究將從另ㄧ影響因素-摩擦力-進行探討。
本研究探討高純度鋁雙晶在受平面壓縮變形(plane strain compression)時，摩擦力對非均勻性變形之形成原因進行討論。為了避免其他雜質在變形過程中形成非均勻性變形，進而無法確認摩擦力的影響，因此本研究選用高純度(99.999%)鋁為實驗材料。在探討異向性變形時，同時結合兩種先進分析技術，分別對塑性變形中所產生之應變量與晶體轉動進行分析，一方面利用以光學照相法(photogrammetry)為基礎的光學量測應變法，將變形過程中之微應變分佈視覺化，藉此可以觀察到塑性變形演變時，單晶在變形過程中並非如Taylor model 中所描述均勻變形，而是＂非均勻性變形 ”。此外，在不同的接觸狀況下，即不同摩擦力，也會發現不同的塑性應變分布。另一方面應用 EBSD 獲得變形前之晶體的初始方位，然後以此初始方位為基礎，利用電腦模擬方法-CPFEM(crystal plasticity finite element method)-預測變形後晶體的方位，藉由比較變形前後的極圖，即可得知變形過程中晶體轉動的方向是沿著ND方向轉動。
從CPFEM模擬的結果中得知摩擦力的大小對其微應變的非均勻性分布與晶體轉動有明顯的相關性，為了進一步了解摩擦力的影響，在此以Sachs模型，藉由改變摩擦力，即為改變外加切應力，探討滑移系統之啟動，進行得知滑移系統之改變造成非均勻性變形。

During the deformation, the influence of grain boundaries plays a less role than that of the intrinsic effects, such as texture, and the extrinsic effects, such as friction. In order to investigate systematically the deformation behavior, the influence of the intrinsic and extrinsic effects should be conducted. The influence of texture had been studied. Therefore, the effect of friction will be investigated in the study.
In the study, aluminum bi-crystals were used to investigate the effect of friction under plane strain compression. In order to avoid the influence of impurities, high purity aluminum (99.999%) were used as raw materials to produce single crystals. Two advanced analytical techniques, photogrammtry and electron backing scattering diffraction (E.B.S.D.), were used to analyze the strain distribution and the lattice rotation during plane strain compression respectively. The lattice orientation determined by E.B.S.D was used as raw orientation for C.P.F.E.M. (crystal plastic finite element method).
It is observed from the results of photogrammtry and C.P.F.E.M simulation that the distribution of the micro-strain is heterogeneous in bi-crystals. In order to investigate the influence of friction, this study utilized Sachs Model to discuss the activation of slip systems and the non-uniform deformation.

目錄
中文摘要 I
英文摘要 Ⅲ
誌謝 Ⅳ
一﹑前言 1
二﹑基礎理論 3
2.1 Bridgman單晶成長技術 3
2.2 連續體力學理論 10
2.3 晶體塑性變形理論 22
2.4 織構基礎理論 31
三﹑材料與實驗方法 40
3.1 實驗材料 40
3.2 變形方法及微應變分析 42
3.3晶體塑性有限元素(CP-FEM)分析 45
3.4實驗流程圖 49
四﹑實驗與模擬結果 50
4.1微應變分析 50
4.2 CP-FEM模擬織構之分析 58
五﹑討論 79
5.1摩擦力對微應變之影響 79
5.2摩擦力對晶體轉動之影響 85
六﹑結論 87
參考文獻 88

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