Experimental Analysis of Control-Parameter Effects on the Solidification Microstructures of Directionally Solidified Lead-Tin Alloys

• Main Authors: Li-ChiehWu, 吳俐潔
• Other Authors: Long-Sun Chao
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/94887257475052376750

碩士 === 國立成功大學 === 工程科學系碩博士班 === 101 === Solidification processes play an important role in the morphology control of microstructures. The morphology of solidification microstructure is difficult to master in a casting process. Accordingly, in the thesis, four experimental models of different heating styles, contact surfaces of copper chill, environment temperatures and casting methods are used to study their effects on the directionally solidified lead-tin alloys. The heating style could affect the grain size. The copper chill supply an axial temperature gradient, which could make columnar grains grow along the opposite directional of the heat flow. The columnar growth could decrease the lateral grain boundaries and elevate the material life span. In addition, the microstructure observation through an optical microscope incorporated with the macrostructures and temperature-measured data is used to investigate the influences of the four experimental models on the constraint of dendrite growth, the equiaxed zone at the bottom of the casting, the competition zone of preferred growth directions for the columnar grains and the grain size. Furthermore, based on the classification of the microstructure morphology, the differences among the castings are analyzed.