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Structural supercooling in directional solidification of single crystal turbine blades is investigated experimentally and numerically. The numerical model uses the finite element calculation of heat flow coupled to a propagation algorithm of the solidification front. Solidification into supercooled melts is treated dependent on the supercooling and recalescence is predicted. The experiment uses a single rod in order to work out the basic understanding of autonomous solidification. In the synergy between numerical modeling and experiment the delicate balance between supercooling, rapid solidification and recalescence can be controlled for effective defect engineering and process time reduction. Thus nearly defect free single crystal turbine blades according to gas turbine manufacturer specifications could be solidified reliably. The processing time is 20 % of that, typically needed by a standard Bridgman process. Furthermore, the tendency to form stray crystals in the critical shroud regions, which is typical for the standard process, was reduced significantly