Kaihua Ji¹, Fatima L. Mota², Younggil Song¹, Jorge Pereda², Trevor Lyons³, Louise L. Strutzenberg⁴, Rohit Trivedi³, Nathalie Bergeon², Alain Karma¹; ¹Northeastern University, ²Aix-Marseille Université and CNRS, ³Iowa State University, ⁴Marshall Space Flight Center

Cellular/dendritic microstructures formed during solidification have a crucial influence on the mechanical properties of a wide range of structural alloys. By minimizing the amount of gravity-induced convection in the liquid, directional solidification experiments using transparent organic alloys conducted in the DECLIC-DSI onboard the International Space Station have provided unique 3D in situ observations of the spatiotemporal evolution of the solid-liquid interface during the formation of cellular and dendritic microstructures under purely diffusive growth conditions. Those observations have made it possible to perform benchmark quantitative comparisons with the predictions of state-of-the-art phase-field simulations of microstructure formation in 3D on experimentally relevant length and time scales. This talk will report quantitative comparisons between microgravity experiments and PF simulations in succinonitrile-camphor alloys of two different compositions that shed new light on the role of subgrain boundaries in the spatiotemporal evolution of the primary cellular spacing and the selection of dendritic array structures.