Speaker:Tamás Pusztai (Wigner RCP SZFI)
Title: Phase-field modeling of directional melting of lamellar and rod eutectic structures
Date: Tuesday, 12 november 2024. 10:00
Place: KFKI Campus, Bldg 1, Conference room
Abstract:
By inverting the pulling direction of the sample in a directional solidification setup, the melting of lamellar and rod eutectic structures can be studied. In the work to be presented, we used phase-field modeling to determine the melting forms of a simple binary model alloy. For samples where the mean composition of the initial solid structure is equal to the eutectic composition, we observed near-planar melting fronts, in agreement with the predictions of a slightly modified Jackson-Hunt analysis. However, if the mean solid composition is off-eutectic, the two solids melt at different positions in the temperature gradient: the phase which is present in a higher-than-eutectic phase fraction melts at its liquidus temperature corresponding to the off-eutectic mean composition, while the other phase melts at the eutectic temperature. The steady-state melting shapes were obtained either by taking the long-time solutions of the dynamical equations of the model, or by solving the time-independent partial differential equations in a reference frame moving with the front. In some cases, non-steady state phenomena, such as oscillations around the trijuction or spherodization could also be observed.
