レーザにより溶融した金属の微小流路内における流動，凝固プロセスの高倍率観察

抄録

The flow and solidification processes of molten metals occur in many processes, such as casting and welding, and understanding the quenching and solidification process is important. However, it is difficult to observe these processes under high magnification in close proximity because of their high temperature. In this study, glass was used as a mold to fabricate microchannels inside. The molten metal was filled into the channels and observed with a high-speed camera with high temporal and spatial resolution. Flow behavior was classified with single step flow (SSF) and double step flow (DSF); DSF was obtained up to the end of the channel, which was about 1000 μm long, and was fast due to it flowed away from the wall surface. In addition, cross sectional observation of the metal after filling revealed multiple internal voids. It is thought that solidification of the root stops the supply and rapid cooling at the wall surface stops the flow.