Selection of the dynamically stable regime of rapid solidification front motion in an isothermal binary alloy

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On the basis of local nonequilibrium approach the dynamics of a motion of the rapid solidification front in a binary alloy is considered. Asymptotic expansion for concentration of solute and its diffusion flux at the front is found in the limit of large times t→∞. A selection criterion for dynamic stability of the front motion in a steady-state regime (V=V0≡const) is formulated. An expression for the definition of a nonstationary time during the transition to the steady-state regime is obtained. The front motion regimes with decreasing velocity in time are investigated. In these regimes the velocity decreases in time as V(t)∼t−1/2 and V(t)∼t−1/3.