Dynamic instabilities of rod-like eutectic growth patterns: A real-time study

作者：Perrut Mikael; Bottin Rousseau Sabine; Faivre Gabriel; Akamatsu Silvere^*

来源：Acta Materialia, 2013, 61(18): 6802-6808.

DOI：10.1016/j.actamat.2013.07.054

• Eutectic solidification
• Directional solidification
• Solidification microstructures

We present a real-time experimental study of the rod-like growth patterns formed during directional solidification in a non-faceted transparent eutectic alloy, succinonitrile (d)camphor. Slightly convex isotherms were used to slowly increase the pattern spacing 2 from an appropriate starting value to the threshold spacing for rod elimination or rod-splitting instabilities allowing a quantitative determination of these thresholds as a function of the solidification rate V. We show that the threshold spacing for rod splitting obeys the general lambda similar to V-1/2 scaling law of eutectic growth, whereas the threshold spacing for rod elimination deviates from this law at low V, exhibiting the same overstability effect as previously reported for lamellar eutectic patterns. We demonstrate that topological defects (walls between hexagon domains) play an important role in rod-splitting processes. We also describe a spatially incoherent mode of oscillation that we observed in disordered rod-like patterns.

• 出版日期2013-10