Here we show the results of
experimental observation of decomposition of the solution components into the
neighboring cells. The
liquid solution under crystallization first gets into the unstable state and
then decomposes. The decomposition result is fixed in the solid phase as inhomogeneous component
distribution. Our experimental results enable to argue that the eutectic
pattern forms due to interface instability and spinodal decomposition of
non-equilibrium solution forming in front of the interface.