摘要
鑄造技術為一項重要的技術，鑄造技術的進步及發展帶動了人類的整體文明的發展，透過不同的鑄造方法及模式，可以獲得具有特殊特性的鑄件，最遠可以追溯至史前4000 年前，人類學會鑄造硬度較高的青銅器，農業和手工業的生產力提高，物質生活條件提升，帶動整體文明的發展，而近代更是有半導體產業廣泛使用的的柴式法（Czochralski Method），藉此製造出單晶矽，帶動了電腦資訊產業及其他產業的發展。
針對方向性凝固，本文使用錫鉛合金（Sn-10 wt.%Pb）為材料，透過不同的實驗條件，研究不同之凝固模式及參數對於微結構之影響。
由不同冷卻介質的實驗比較，液態氮冷卻組別的 G·V 值皆較水冷組別的 G·V 值來得高，並且，使用液態氮為冷卻介質所得到之鑄件的微結構尺寸相對於使用水為冷卻介質的微結構尺寸來得小。由無施加磁場及有施加磁場的實驗比較，可發現有施加磁場的組別位於中間的晶粒尺寸皆較邊界小，另外有施加磁場的組別平均晶粒尺寸較大。
關鍵字：鑄造、方向性凝固、錫鉛合金、冷卻介質、磁場

Effect of Cooling Medium and Magnetic Field on the Microstructure of
Directionally Solidified Pb-Sn Alloys
Author: Chia-Lin Chang
Advisor: Prof. Long-Sun Chao
Department of Engineering Science, National Cheng Kung University
SUMMARY
Casting is an important technology. Its earliest origin can be traced back from the Stone Age to the Bronze one and this is an archaeological turning point. Humans learned to cast bronze with the higher hardness, and the productivity of agriculture and handicrafts was improved. The material improvement of living conditions drives the development of the overall civilization. In modern times, the Czochralski Method, widely employed in the semiconductor industry, is used to create single crystal. This has driven the development of the computer industry and other industries. In the study, for directional solidification, the tin-lead alloy (Sn-10 wt.% Pb) was used as the material to study the effects of different solidification modes and parameters on the microstructure through different experimental conditions. Comparing the experimental results of different cooling mediums, the G·V values of the liquid nitrogen cooling models are higher than those of the water cooling models. The microstructure size of a casting using liquid nitrogen as the cooling medium is smaller than that using water as the cooling medium.
The experiments without any magnetic field applied is compared to the ones with a magnetic field employed. It can be found that the average grain size of the experiments without any magnetic field applied is smaller than that with a magnetic field applied.
Comparing the grain size in the middle area and near the edge of the experiments with a magnetic field applied, it can be found that the grain size near the edge is bigger than that in the middle area.
Keywords: Casting, Directional Solidification, Pb-Sn Alloy, Cooling Medium,
Magnetic Field.

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