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<p>Anomalous elimination refers to a dendrite competition outcome that deviates from the predictions of the classical Walton–Chalmers model during directional solidification. This phenomenon may contribute to the expansion of defects, thereby degrading the mechanical properties of single crystal alloys. However, the underlying mechanism of anomalous elimination remains poorly understood. In this work, the phase-field model, which comprehensively considers the temperature gradient, multi-components segregation, and melt convection, is developed to simulate the dendrite growth and competition process. The simulation result indicated that the melt convection is able to change dendrite morphology and thus may affect the dendrite competition through affecting the distribution of solutes around dendrites. At converging grain boundaries, when the melt flows from the favorably oriented dendrite side toward the unfavorably oriented dendrite side, convection benefits the growth of the unfavorably oriented dendrites, which may induce anomalous elimination. At diverging grain boundaries, the favorably oriented dendrites have a spatial advantage for developing tertiary arms. Melt convection at typical velocities (below 10&#xa0;mm/s) is insufficient to reverse the competitive outcome at diverging boundaries.</p>

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Anomalous Elimination Mechanism Under Melt Convection During Directional Solidification Process

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Huxiang Xia,
  • Yeyuan Hu,
  • Shaoxiang Li,
  • Qingyan Xu,
  • Hongbiao Dong

摘要

Anomalous elimination refers to a dendrite competition outcome that deviates from the predictions of the classical Walton–Chalmers model during directional solidification. This phenomenon may contribute to the expansion of defects, thereby degrading the mechanical properties of single crystal alloys. However, the underlying mechanism of anomalous elimination remains poorly understood. In this work, the phase-field model, which comprehensively considers the temperature gradient, multi-components segregation, and melt convection, is developed to simulate the dendrite growth and competition process. The simulation result indicated that the melt convection is able to change dendrite morphology and thus may affect the dendrite competition through affecting the distribution of solutes around dendrites. At converging grain boundaries, when the melt flows from the favorably oriented dendrite side toward the unfavorably oriented dendrite side, convection benefits the growth of the unfavorably oriented dendrites, which may induce anomalous elimination. At diverging grain boundaries, the favorably oriented dendrites have a spatial advantage for developing tertiary arms. Melt convection at typical velocities (below 10 mm/s) is insufficient to reverse the competitive outcome at diverging boundaries.