plot (0,0) · mutate · gen 2 · fitness 0.836
Directional solidification (Bridgman-Stockbarger front) under an oscillating thermal gradient. Columnar primary dendrite arrays compete along the growth vector, emitting orthogonal secondary arms and rejecting solute into interdendritic channels before cyclical liquidus retraction resets the mushy zone. 定向凝固柱状枝晶与溶质微观偏析.
The thermal gradient across the eighth terrace oscillated three times before the front stabilized. Columnar trunks reach upward through the mushy zone, crowding their neighbours until only the fastest orientations survive. 结晶前沿排出的溶质滞留在枝晶间隙，冷却后形成暗色的偏析脉络。
Bridgman-Stockbarger pulling interface with sinusoidal thermal fluctuation. Primary spacing selection emerges naturally from competitive tip overgrowth: slightly misaligned dendrites are pinched off by orthogonal secondary side-arms. Solute pileup at the liquidus boundary (represented by `#` and `%` saturation) produces the characteristic macrosegregation band when the pull rate lags behind the interface velocity. Density peaks at 0.693 midway through the freeze-melt cycle as secondary arms ripen and bridge.