Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Science. 2021 Oct 8;374(6564):189-193. doi: 10.1126/science.abj3210. Epub 2021 Oct 7.
Grain boundary velocity has been believed to be correlated to curvature, and this is an important relationship for modeling how polycrystalline materials coarsen during annealing. We determined the velocities and curvatures of approximately 52,000 grain boundaries in a nickel polycrystal using three-dimensional orientation maps measured by high-energy diffraction microscopy before and after annealing at 800°C. Unexpectedly, the grain boundary velocities and curvatures were uncorrelated. Instead, we found strong correlations between the boundary velocity and the five macroscopic parameters that specify grain boundary crystallography. The sensitivity of the velocity to grain boundary crystallography might be the result of defect-mediated grain boundary migration or the anisotropy of the grain boundary energy. The absence of a correlation between velocity and curvature likely results from the constraints imposed by the grain boundary network and implies the need for a new model for grain boundary migration.
人们一直认为晶界速度与曲率有关，这对于模拟多晶材料在退火过程中的粗化非常重要。我们使用高能衍射显微镜测量的三维取向图，在 800°C 退火前后确定了镍多晶中约 52000 个晶界的速度和曲率。出乎意料的是，晶界速度和曲率之间没有相关性。相反，我们发现晶界速度与指定晶界晶体学的五个宏观参数之间存在很强的相关性。边界速度对晶界晶体学的敏感性可能是缺陷介导的晶界迁移或晶界能量各向异性的结果。速度与曲率之间没有相关性可能是由于晶界网络施加的约束所致，这意味着需要新的晶界迁移模型。
