Grain boundary directed spinodal decomposition has a substantial effect on the microstructure evolution and properties of polycrystalline alloys. The morphological selection mechanism of spinodal decomposition at grain boundaries is a major challenge to reveal, and remains elusive so far. In this work, the effect of grain boundaries on spinodal decomposition is investigated by using the phase-field model. The simulation results indicate that the spinodal morphology at the grain boundary is anisotropic bicontinuous microstructures different from the isotropic continuous microstructures of spinodal decomposition in the bulk phase. Moreover, at grain boundaries with higher energy, the decomposed phases are alternating α/β layers that are parallel to the grain boundary. On the contrary, alternating α/β layers are perpendicular to the grain boundary.

晶界定向的旋节线分解对多晶合金的微观结构演变和性能有重大影响。晶界旋节线分解的形态选择机制是揭示的主要挑战，到目前为止仍然难以捉摸。在这项工作中，使用相场模型研究了晶界对旋节线分解的影响。模拟结果表明，晶界处的旋节线形貌是各向异性双连续微观结构，不同于体相中旋节线分解的各向同性连续微观结构。此外，在具有较高能量的晶界处，分解相交替α / β平行于晶界的层。相反，交替的α / β层垂直于晶界。