Experimental and modelling studies for solidification of undercooled Ni-Fe-Si alloys

We present experimental results, analytical calculations and phase-field simulations for undercooled Ni-Fe-Si alloy system. Undercooling experiments are performed using flux encapsulation along with in situ measurement of recalescence speed using a high-speed camera followed by microstructural characterization. Dendrite growth calculations are performed using a modified Boettinger, Coriell and Trivedi theory to incorporate constitutional undercooling due to multiple segregating elements and a modified kinetic undercooling term. Phase-field simulations are performed using a multi-component phase-field model to generate dendrites in this alloy. High growth velocities are observed and the analytical calculations are in good agreement with experiments. The microstructure evolution from the phase-field simulations indicates that there is a difference in solute segregation during growth of dendrites. This article is part of the theme issue 'Heterogeneous materials: metastable and non-ergodic internal structures'.