Department of Materials Science and Engineering, Faculty of Engineering
Department of Materials, Graduate School of Engineering
Department of Materials, School of Engineering
Crystal growth from melt is a phase transformation from the liquid phase to the solid phase, and there are a myriad of factors that must be controlled during this process, such as complex shapes and variations in the concentration of alloying elements within the melt. In our laboratory, we are studying the control process so as to allow various structural and functional materials such as metals, semiconductors, and ceramics to develop into microstructures that achieve the desired properties. For example, silicon crystals for solar cells are manufactured by unidirectional crystal growth in silicon melt. Since the crystal quality greatly affects the energy conversion efficiency, microstructure control is performed to achieve polycrystalline silicon with a high performance. In addition, some components of transportation machines such as automobiles are manufactured by melting and solidifying lightweight aluminum and magnesium alloys. Since impurities and bubbles may be entrained in the molten alloy flow, we are studying the control of flow and solidification structure to remove dispersed impurities. In addition, the properties of products are affected greatly by the shape and distribution of microstructures, which are determined in a large range for some products such as steel plates manufactured in steel plants and cast iron solidified in molds, or in a small range for other products such as objects fabricated with metal 3D printers by repeated melting and solidification. We are investigating the principles of crystal growth, solidification and casting, and their control methods to realize high-performance materials.
Sequence of metal 3D printing.