Peritectic reaction and its influences on the microstructures evolution during directional solidification of Fe-Ni alloys

Systematic directional solidification experiments were carried out in Fe-Ni peritectic alloys to investigate the influences of peritectic reaction on the microstructures evolution. Various microstructures were observed in the directionally solidified samples, such as bands, mixed bands, island banding, tree-like oscillatory pattern, coupled and cellular coupled growth structures. It was found that peritectic reaction occurs near the trijunctions during the two-phase growth at different interface morphologies of the primary phase observed as planar, cellular and dendritic. Peritectic reaction makes the liquid/δ/γ trijunctions region quite irregular and makes the trijunctions dynamics quite complicated, and thus plays an important role in the formation of various microstructures.