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Containerless processing of droplets and drops by atomization and electromagnetic levitation are applied to undercool metallic melts and alloys prior to solidification. Heterogeneous nucleation on crucible walls is completely avoided giving access to large undercoolings. Experiments are performed both under terrestrial (1 g) conditions and in reduced gravity (µg) as well. Microgravity conditions are realized by the free fall of small droplets during atomization of a spray of droplets, individual drops in a drop tube and by electromagnetic levitation of drops during parabolic flights, sounding rocket missions, and using the electro-magnetic levitator multi-user facility on board the International Space Station. The comparison of both sets of experiments in 1 g and µg leads to an estimation of the influence of forced convection on dendrite growth kinetics and microstructure evolution.

The phase-field method has become the method of choice for simulating microstructure formation during solidification. Recent progress, both on the formulation of the model and on the numerical implementation, makes it now possible to simulate quantitatively the evolution of complex microstructures in three dimensions. This is illustrated by simulations of eutectic coupled growth. The morphological stability of lamellar patterns is investigated, and the results are compared to experimental data obtained by in situ observations of the transparent alloy carbontetrabromide-hexachloroethane. When the lamellar spacing exceeds a critical value, a zigzag instability occurs. The further evolution of the system leads to stable zigzag structures or lamella breakup, depending on the parameters.