一般的鑄造過程是不易控制其凝固結構之形態，最多只能改變其晶粒大小，而方向性凝固與單晶成長屬於高難度之鑄造技術，需使用適當的鑄造機制來控制凝固結構形態，而單晶之製程是最困難的，方向性成長則次之，不過方向性成長是單晶製程之基礎。
本論文採用三種不同實驗模式加以探討方向性凝固之製程參數，模式A是採用AR-25與AR-50之冒口材料鑄件外模和石墨模等三種不同孔徑與材質之鑄模並搭配三種載台下降速率，載台下降速率於本文設定為0.05~0.2mm/s。模式B是改變加熱器電源之操作選項，模式C是固定鑄模材質和載台速度但改變上下加熱器的溫度差，以錫鉛合金為測試材料，液態時完全融合，固體與液體具有溶解度差異，由於偏析之作用使得凝固過程中會生成共晶結構，使用光學顯微鏡觀察凝固之顯微結構，並計算其結構參數，利用熱偶線與溫測擷取系統量測鑄件軸向溫度分佈。
本文的目的是探討於方向性凝固實驗中，採用固定濃度(Sn-10wt.%Pb)的錫鉛合金，其鑄件之凝固參數(Solidification parameter)，如冷卻曲線、溫度梯度和成長速率，與枝狀晶的結構參數(Structure parameter)，如主枝狀晶臂間距（Primary arm spacing, λ1）與二次枝狀晶臂間距（Secondary arm spacing, λ2），於方向性凝固時的相互關係，並搭配濕砂模實驗之鑄件量測其導電率之差異性，驗證不同長晶結構之物理特性，並由分析結果掌握方向性凝固的控制機制。

The morphology of solidification microstructure is difficult to control in a casting process, in which only the grain size can be easily changed. To perform advanced casting techniques such as the directional solidification and the single crystal growth, a proper casting mechanism is needed to control the solidified microstructure. Among these solidification processes, the single crystal growth is the most difficult one and the directional solidification is the second. However, the fabricating technique of single crystal is based on that of directional solidification. This paper investigated into the control parameter of the directional solidification with three different experiment models. In these models, three kinds of casting mold, two types of heating power operation (turning on and off) and three different platform-descending rates are used to study the directional solidification of lead-tin alloy. An optical microscope is utilized to observe the solidifying microstructure and thermal couples are applied to measure the temperatures along the axial direction of cylindrical casting. From the microstructures and temperature distributions obtained from the experiments, the relationship between the solidification and structure parameters is investigated, where the solidification parameters are temperature gradient (G) and growth rate (V) and the structure ones are primary arm spacing (λ1) and the secondary arm spacing (λ2). Besides, the electrical conductivity of sample in which the sand casting and the directional solidification are measured for verified the effect of microstructure characteristic. From these analysis results, the controlled mechanism of the directional solidification can be further grasped.

[1] 李魁盛， “鑄造工藝設計基礎” ，機械工業出版社，1981
[2] 陸文華， “鑄鐵及其熔煉” ，機械工業出版社，1981
[3] C. M. Klaren, J. D. Verhoeven, and R. Trivedi,“Primary Dendrite Spacing of Lead Dendrite in Pb-Sn and Pb-Au Alloy,” Metallurgical Transactions A29,pp.1853-1861(1980)
[4] D. G. McCartney, and J. D. Hunt, “Measurements of Cell and Primary Dendrite Arm Spacings in Directionally Solidified Aluminum Alloys.” Acta Metallurgica Vol. 29, pp.1851-1863(1981)
[5] Guolu Ding, Weidong Huang, Xin Lin, and Yaohe Zhou “Predication of Average Spacing for Constrained Cellular/Dendrite Growth,”Journal of Crystal Growth 177, pp.281-288(1997)
[6] C. T. Rios, and R. Caram, “Priamry Dendrite Spacing as a Function of Directional Solidification Parameters in an Al-Si-Cu Alloy,” Journal of Crystal Growth174, pp.65-69(1997)
[7]Ming Li, Takassuke Mori, and Hajime Iwasaki, “Effect of Solute Convection on The Primary Arm Spacings of Pb-Sn Binary Alloys During Upward Directional Solidification,” Materials Science and Engineering A265, pp.217-223 (1999).
[8]E. Cadirli, and M. Gunduz, “The Directional Solidification of Pb-Sn Alloys,” Journal of Materials Science 35, pp.3837-3848 (2000).
[9] E. Cadirli, and M. Gunduz, “ The Dependence of Lamellar Spacing on Growth Rate and Temperature Gradient in the lead-tin Eutectic Alloy”, Journal of Materials Processing Technology 97, pp.74-81 (2000).
[10] JUN Hui, R. Tiwari, X. Wu, S.N. Tewari, and R. Trivedi, “Primary Dendrite Distribution and Disorder during Directional solidification of Pb-Sb Alloys”, Metallurgical and Materials Transactions V33A,pp.3499-3510 (2002).
[11] Otavio Lima Rocha, Claudio Alves Siqueira, and Amauri Garcia, “Cellular/Dendritic Transition During Unsteady-State Unidirectional Solidification of Sn-Pb Alloys,” Materials Science and Engineering A347, pp.59-69 (2003).
[12] Otavio Lima Rocha, Claudio Alves Siqueira, and Amauri Garcia,“Cellular Spacings in Unsteady-State Directionally Solidified Sn-Pb Alloys,” Materials Science and Engineering A361, pp.111-118 (2003).
[13] Fernando sa, Otavio Lima Rocha, Claudio Alves Siqueira, and Amauri Garcia, “The Effect of Solidification Variables on Tertiary Dendrite Arm Spacing in Unsteady-State Directional Solidification of Sn-Pb and Al-Cu alloys,” Materials Science Engineering A373, pp.131-138 (2004).
[14] Jinjiang Yu, Jun Zhang, Feng Wang, Jinshang Li, Hengzhi Fu, “Microstructure evolution of Ni, Cr, Al-TaC in situ composite directionally solidified under a high temperature gradient,” Materials Science and Engineering A311 pp.200-204(2001)
[15] Jinshan Li, Qitang Hao, Shuangming Li, Hongchao Kou, Jianguo Li, Hengzhi Fu, “Research on the non-linear temperature field of molten metal shaped by an electromagnetic field in DS processing,” Journal of Materials Processing Technology 137 pp.145-150(2003)
[16] 林錦逢， “GTE爐結晶成長之模式研究” ，成功大學工程科學研究所碩士論文(1994)
[17] 蘇彥慶，郭景哲，劉暢，郭景杰，賈均，傅恒志， “定向凝固技術與理論研究的進展”,”SPECIAL CASTING & NONFERROUS ALLOYS (2006)
[18] L. Sturz, A. Drevermann, C. Pickmann, G. Zimmermann, “Influence of grain refinement on the columnar-to-equiaxed transition in binary Al alloys,” Materials Science and Engineering A pp. 379-383(2005)
[19] A.E. Ares, S.F. Gueijman, R. Caram, C.E. Schvezov, “Analysis of solidification parameters during solidification of lead and aluminum base alloys,” Journal of Crystal Growth 275 pp.319-327(2005)
[20] 何廣福， “方向性凝固之研究”,成功大學工程科學研究所碩士論文(2005)
[21] 林五祥， “熱與溶質效應對於錫鉛合金方向性凝固之影響分析”,成功大學工程科學研究所碩士論文(2006)
[22]呂璞石，黃振賢，金屬材料，文京圖書，p.39(1990)
[23] J.E. Spinelli, I.L. Ferreira, A. Garcia, “Influence of melt convection on the columnar to equiaxed transition and microstructure of downward unsteady-state directionally solidified Sn-Pb alloys,”Journal of Alloys and Compounds 384 pp.217-226(2004)
[24] H. Kaya, E. Cadirli, M. Gunduz, “Dendritic Growth in an Aluminum-Silicon Alloy,”ASM International(2006)
[25] 汪建民，“材料分析” ，中國材料科學學會，1998
[26] 徐國華，“材料進階實驗（二）” ，逢甲大學材料科學實驗
[27] 李春穎、許煙明、陳忠仁，“材料科學與工程” ，高立圖書，pp.724(1994)
[28] 鍾朝嵩，“計量值數據如何統計” ，先鋒企業管理發展中心，pp54~72
[29] 李文斌、袁芳洲，“統計學”，美商麥格羅.希爾國際股份有限
[30] 黃登源，“應用迴歸分析”，華泰文化事業公司，pp366公司，pp80~82