Influence of sample thickness on the morphology of eutectic system

In situ observation on eutectic morphological evolution was carried out during directional solidification of transparent organic alloy CBr₄-11.7%C₂Cl₆ (mole fraction). The influences of sample thickness on the anisotropy effect of interface energy and the adjustment mechanism of lamellar spacing in the initial transient of eutectic solidification were investigated. It is found that the anisotropy effect and the adjustment mechanism depend on the sample thickness remarkably. The anisotropy effect can be ignored when the thickness is larger than 48 μm. When the thickness is less than 48 μm, the anisotropy effect became distinct, which makes the growth direction of some eutectic lamellae deviated away from the direction of temperature gradient due to the orientation difference of prior grains. When the thickness reaches 16 μm, the adjustment mechanism changed from initial multi-lamella mechanism to quasi-two dimensional one.