Directional solidification of cellular arrays in a transparent organic alloy Original Research Article

A new experimental database for supercritical cellular solidification close to the planar-cellular transition in bulk samples is presented. Using the transparent alloy Succinotrile-0.075 wt % Acetone a series of directional solidification experiments were performed under free-falling conditions of space to provide purely diffusive growth. The cellular patterns observed in top-view were analysed concerning their main quantitative parameter primary spacing. It is found that no sharp wavelength selection occurs. For the primary spacing as well as for the number of neighbours of each individual cell the patterns reveal wide distributions which remain statistically unchanged in the final state of the experiments. The theoretical evaluation of the cellular patterns focused on a comparison of linear stability analysis with experimental results. While cellular patterns in a subcritical regime are controlled by higher harmonics the linear mode is sufficient to explain the observed database in the supercritical regime.