Real-time study of thin and bulk eutectic growth in succinonitrile-(D)camphor alloys

We study the directional-growth patterns of the transparent nonfaceted alloy succinonitrile-(D)camphor (SCN-DC) at eutectic concentration in thin and bulk samples using real-time observation methods. We measure in situ the minimum-undercooling spacing) lambda(m) and the small-spacing stability limit lambda(c) of the thin, quasi-lamellar patterns. We find lambda(2)(m) V approximate to 10.2 mu m(3) s(-1) and lambda(c) approximate to 0.65 lambda. This last result is contrary to the common conjecture that in lamellar patterns, but in agreement with previous experimental and numerical studies in the CBr4-C2Cl6 eutectic. In bulk samples, we observe the growth of rod-like patterns in real time. We show that these patterns do not usually achieve long-range hexagonal order after long solidification times, although their average spacing reaches a constant value, which is close to), after a relatively short transient. (c) 2007 Elsevier B.V. All rights reserved.