Product Code: ICAL09_M1003

Visualization of Grain Boundaries by Nanosecond Laser Irradiation for Controlling Microstructures of Metals
Authors:
Masahiro Tsukamoto, Joining and Welding Research Institute; Ibaraki, Osaka Japan
Saburo Yagi, Graduate School of Osaka Univ.; Suita, Osaka Japan
Toshiya Shibayanagi, Joining and Welding Research Institute; Ibaraki, Osaka Japan
Masayuki Fujita, Institute for Laser Technology; Suita, Osaka Japan
Nobuyuki Abe, Joining and Welding Research Institute; Ibaraki, Osaka Japan
Presented at ICALEO 2009

Fiber laser spot heating for controlling microstructures is an important technology for production of new functional materials. Function of materials depends on their microstructures which include shape, size of grains and phase, grain orientation and grain boundary structure. Microstructures are revealed by Electron Back-Scatter Diffraction pattern (EBSD) analysis. In our previous study, we developed a fiber laser spot heating system in order to modify the microstructures of aluminum (Al) plate. However, the grains were not selected since the grain boundaries could not be observed in the system. To obtain new functions by controlling the microstructures, technology of selecting grains before a fiber laser spot heating was required. We focused on difference of melting point between the grains and the grain boundaries. It is known that melting point of the grain boundaries is lower than that of the grains. By pulsed laser irradiation, the grain boundaries might be visualized due to the difference of melting point between the grains and the grain boundaries. In this study, the grain and the grain boundaries of Al plate was irradiated with nanosecond laser before the fiber laser spot heating process. Grain boundaries could be visualized after the nanosecond laser irradiation.