本研究是將高斯分布的能量照射在金屬鐵上，已探討表面活性元素硫和不同能量束半徑，並使金屬鐵表面受到一集中熱源加熱達到熔融狀態，進而產生鎖孔的暫態熱流行為之影響。本研究採用Comsol套裝軟體，求解二維暫態模型、相位場法、質量方程式、動量方程式、能量方程式，及相位場函數以模擬金屬鐵表面。本研究忽略濃度擴散所造成的影響。結果顯示溫度變化而產生熱毛細力之梯度所造成熔區流動及鎖孔的現象。

In this study, the shape of molten pool is irradiated by the energy flux of Gaussian distribution, for different surface active element sulfur and beam intensities is discussed. A keyhole can be produced by a concentrated the energy flux. The model proposed including two-dimensional transient, phase-field method, mass conservation equation, momentum equation, energy equation and phase-field function. Finally, the computer result the effect of thermocapillary force on the flow behavior in the molten region and the development of keyhole.

論文審定書 i
誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 ix
符號說明 x
第一章 緒論 1
1.1 文獻回顧 1
1.2 研究目的 1
1.3 論文簡介 2
1.4 相位場法 (Phase-field method) 2
第二章 數學模型之假設與統御方程式 4
2.1 基本假設與物理模型 4
(2.1.1) 基本假設 4
(2.1.2) 物理模型 5
2.2 數學模型與統御方程式 5
(2.2.1) 相位場函數 5
(2.2.2) 連續方程式 7
(2.2.3) 動量方程式 7
(2.2.4) 能量方程式 12
(2.2.5) 表面張力方程式 12
2.3 模型架構與邊界條件 13
(2.3.1) 模型架構 13
(2.3.2) 網格設定 14
(2.3.3) 初始值設定和邊界條件 15
(2.3.4) 流程圖 16
第三章 模擬結果與討論 17
3.1 模擬條件 17
(3.1.1) 各種材料之基本性質 17
(3.1.2) 基本性質的模擬圖 18
(3.1.3) 模擬說明 21
3.2 結果討論 39
(3.2.1) 表面活性元素對熔區之影響 39
(3.2.2) 熱毛細力對熔區之影響 40
(3.2.3) 能量束半徑對熔區之影響 40
(3.2.4) 網格驗證 40
第四章 結論與未來展望 41
4.1 結論 41
4.2未來展望 41
参考文獻 42

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