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M: Metallphysik

M 23: Phasenumwandlung III

M 23.4: Vortrag

Samstag, 5. März 2005, 15:30–15:45, TU H1058

Phase-field simulations of solidification structures in multicomponent (Ni-Cu-Cr) and multiphase (Al-Cu) alloys — •Denis Danilov and Britta Nestler — Karlsruhe University of Applied Sciences, Karlsruhe, Germany

Phase transformations in multicomponent and multiphase (e.g. eutectic) systems play a major role during solidification processes of a variety of alloys. Using a general phase-field model we investigate growth microstructures and their dependence on solidification conditions in such systems. In ternary Ni-Cu-Cr alloy a morphological transition from dendritic to globular growth is found by varying the alloy composition at a fixed underccoling. The dependence of the growth velocity and of the impurity segregation in the solid phase on the composition is analyzed and indicates a smooth type of transition between the dendritic and globular structures. The stability of lamellar eutectic structure in Al-Cu alloy is investigated and two possible types (regular and oscillatory) of the growth structures have been found depending on the lamellar spacing and on the off-eutectic composition. The work was supported by DFG under project No. Ne 882/2.