Quantitative phase-field modeling of solidification in binary alloys with nonlinear phase coexistence curves
Chaohui Tong, Michael Greenwood, and Nikolas Provatas

A formalism is presented for performing quantitative phase field simulations of single-phase solidification in binary alloys with non-linear solidus and liquidus curves. It is shown that, close to equilibrium, the Gibb's free energy of an alloy phase can be approximated by the free energy function of a dilute ideal binary alloy, modified by \emph{effective} temperature dependent coefficients. This makes it possible to exploit a recent phase field technique [A. Karma, PRL, {\bf 87}, 115701 (2001)] to model the free boundary kinetics of single-phase solidification in binary alloys having non-linear phase coexistence curves. Simulations of isothermal and non-isothermal dendritic solidification in an isomorphous binary alloy are used to demonstrate convergence of tip speed and radius for different values of the phase field interface thickness. The effect linear versus non-linear phase boundaries on dendritic tip speed is examined.

© 2008 The American Physical Society.