Microstructure evolution of Cu-Mn alloy under laser rapid solidification condition - Banded structure and planar front growth

Banded structure is a novel microstructure found in the high energy beam surface rapid solidification experiments in recent years. However, its growth mechanism is still not well understood. Laser rapid solidification experiments have been performed on Cu-Mn alloy to investigate its microstructure evolution with growth rate. Both banded structure and planar front growth morphology have been clearly observed in laser molten pool. Based upon experimental observations and theoretical analyses, the origin of the banding is elucidated. A study on the critical condition of planar front growth demonstrates that M-S stability theory predicts this condition quite well.