Grain boundary formation during coarsening of nanoporous gold (NPG) is investigated wherein a nanocrystalline structure can form by particles detaching and reattaching to the structure. MicroLaue and electron backscatter diffraction measurements demonstrate that an in-grain orientation spread develops as NPG is coarsened. The volume fraction of the NPG sample is near the limit of bicontinuity, at which simulations predict that a bicontinuous structure begins to fragment into independent particles during coarsening. Phase-field simulations of coarsening using a computationally generated structure with a volume fraction near the limit of bicontinuity are used to model particle detachment rates. This model is tested by using the measured NPG structure as an initial condition in the phase-field simulations. We predict that up to ∼5% of the NPG structure detaches as a dealloyed Ag75Au25 sample is annealed at 300 °C for 420 min. The quantity of volume detached is found to be highly dependent on the volume fraction and volume fraction homogeneity of the nanostructure. As the void phase in the experiments cannot support independent particles, they must fall and reattach to the structure, a process that results in the formation of new grain boundaries. This particle reattachment process, along with other classic processes, leads to the formation of grain boundaries during coarsening in nanoporous metals. The formation of grain boundaries can impact a variety of applications, including mechanical strengthening; thus, the consideration and understanding of particle detachment phenomena are essential when studying nanoporous metals.

研究了纳米多孔金 (NPG) 粗化过程中的晶界形成，其中纳米晶体结构可以通过颗粒分离和重新附着到结构上而形成。MicroLaue 和电子背散射衍射测量表明，随着 NPG 的粗化，晶粒内的取向扩展会发展。NPG 样品的体积分数接近双连续性的极限，在该极限处，模拟预测双连续结构在粗化过程中开始分裂成独立的粒子。使用体积分数接近双连续性极限的计算生成结构进行粗化的相场模拟用于模拟粒子脱离率。通过使用测量的 NPG 结构作为相场模拟中的初始条件来测试该模型。一个G75一个你25样品在 300 °C 下退火 420 分钟。发现分离的体积量高度依赖于纳米结构的体积分数和体积分数均匀性。由于实验中的空隙相不能支撑独立的粒子，它们必须下落并重新附着到结构上，这一过程会导致新晶界的形成。这种粒子重新附着过程以及其他经典过程会导致纳米多孔金属在粗化过程中形成晶界。晶界的形成会影响多种应用，包括机械强化；因此，在研究纳米多孔金属时，对粒子脱离现象的考虑和理解是必不可少的。