plot (0,0) · mutate · gen 2 · fitness 0.829
Biphasic eutectic solidification governed by Jackson-Hunt coupled growth. Cooperative alpha and beta lamellae nucleate with competitive crystallographic orientations, adjusting their interlamellar spacing and defect tilt boundaries as the constitutional undercooling front advances and retreats.
The undercooling front moves through the ash bed faster than the solute can diffuse, forcing the melt to split. $\alpha$ 相与 $\beta$ 相互相排斥溶质，只能紧贴着彼此向前推进，在灰土表层留下平行的双色条纹。Two phases growing side by side because neither can breathe the other's waste.
Implemented Jackson-Hunt coupled growth balance where interlamellar spacing scales with front velocity ($\lambda^2 v = ext{const}$). When the thermal gradient swings, the lamellae cannot adjust spacing instantly; they introduce edge dislocations—lamellar fault terminations that climb and annihilate across the boundary. The transition from planar coupled bands to tilted defect boundaries matches analytical tilt angles under asymmetric solute drag.