Abstract: Two-dimensional and three-dimensional phase field models were constructed using KKS model to investigate the three-dimensional microstructure growth mechanism of Fe-1.5% C alloy during solidification.Through high-temperature laser confocal technology， in-situ observation of the binary alloy structure is achieved， and the observed results are compared with simulation data to verify the accuracy of the phase-field simulation. The results indicate that the length of dendrite growth is significantly different at different cooling rates.Further analysis reveals that the three-dimensional phase-field simulation exhibits higher accuracy in predicting dendrite growth during alloy solidification compared to two-dimensional simulations. When the cooling rate is 2 000 ℃/min， the primary dendrite growth length in the three-dimensional simulation reaches 0.6 µm， which is close to the experimental value of 0.5 µm. However， when the cooling rate increases to 3 000 ℃/min， the three-dimensional simulation result is 1.4 µm， highly consistent with the experimental observation value of 1.45 µm. Additionally， the anisotropy strength plays a decisive role in dendrite growth， with a critical value of 0.045 determining the stability of dendrite growth in both two-dimensional and three-dimensional spaces. Once this critical value is exceeded， it will lead to the dendrite instability

Key words: Fe-1.5% C alloy, Dendrite Growth, High-temperature Laser Confocal Microscopy, Binary Alloy

摘要： 运用KKS模型构建二维及三维相场模型，探究Fe-1.5% C合金在凝固阶段的三维微观组织生长机制。通过高温激光共聚焦技术，实现二元合金结构的原位观测，并将观测结果与模拟数据进行对比，以此验证相场模拟的准确性。研究结果表明，不同冷却速率下，枝晶生长的长度存在明显差异。进一步分析发现，三维相场模拟在预测合金凝固过程中枝晶生长情况的准确性高于二维模拟。当冷却速率为2 000 ℃/min时，三维模拟中主枝晶生长长度达到0.6 µm，与实验值0.5 µm相近；而当冷却速率提升至3 000 ℃/min时，三维模拟结果为1.4 µm，与实验观测值1.45 µm高度一致。此外，各向异性强度对枝晶生长具有决定性作用，其值在0.045临界点时，决定了二维和三维空间中枝晶生长的稳定性，一旦超过此临界值，会导致枝晶发生失稳现象。

关键词: Fe-1.5% C合金, 枝晶生长, 高温激光共聚焦, 二元合金