Primary cellular/dendritic spacing selection in rapidly solidified peritectic alloy

Primary cellular/dendritic spacing plays an important role in the microstructure control under rapid solidification conditions, here laser resolidification experiments have been performed with Ti–Al alloys to clarify the growth mechanism of peritectic reaction. By taking both transverse and longitudinal sections of the directional growth cells/dendrites in laser traces, the primary phase separation, primary cellular/dendritic spacing, as well as the local solidification velocity are quantitatively determined by means of SEM and TEM. With the solidification velocity increasing, the primary phase evolves from phase α, two-phase (α + γ), to single-phase γ, and the corresponding primary cellular/dendritic spacing decreases gradually. The experimental observation of primary spacing evolution exhibits a good agreement to the prediction of rapid dendritic growth model in all single-phase regions.