Qualititative Analysis of Interface Behavior under First Phase Transition

At present there is no explanation of the nature of interface instability upon first order phase transitions. The well-known theory of concentration overcooling under directed crystallization of solutions and Mullins-Sekerka instability cannot account for the diversified liquid component redistribution during solid state transition. In [1-3], within the framework of the nonequilibrium mass transfer problem, it has been shown that there are regimes of the interface instability, which differ from the known ones [4-6]. Moreover, the instability theory of works [1-3] demonstrates a complete experimental agreement of the dependence of eutectic pattern period on interface velocity. However, it is difficult to explain interface instability within the framework of a general setting of the mass-transfer problem. This paper is de-voted to qualitative analysis of the phenomena that are responsible for interface instability. The phenomena are connected by a single equation. Qualitative analysis revealed a variety of different conditions responsible for instability of flat interface stationary movement upon phase transition. The type of instability depends on system parameters. It is important that interface instability in the asymptotic case of quasi-equilibrium problem setting is qualitatively different from interface instability in the case of nonequilibrium problem setting.