DMREF: Grain Growth Beyond Isotropic Models: Microstructure Evolution with Experimentally-Derived Interface Properties

非技术描述：几乎所有的人造固体都是由许多被称为颗粒的小晶体组成的。这些颗粒的大小和它们附着的方式——材料制成时决定的特征——影响了固体的许多特性。加工过程中晶粒演化的现有模型无法预测观察到的结果。由于问题的复杂性，要准确预测谷物在加工过程中如何演变甚至不太可能。这项研究将验证这样一个假设，即如果包含了关于颗粒之间界面特性的信息，就有可能预测材料中颗粒的演变。这项研究将把模拟与新开发的实验技术结合起来，以检验这一假设。将采用各种方法来确定当前模型的不足之处，如何改进它们，以及预测晶粒演化的可能程度。这项研究更广泛的影响是，预测加工过程中晶粒变化的能力将使人们有可能避免反复试验，以更低的成本更快地开发出改进的材料。技术描述：准确预测在热退火过程中微观结构的演变是材料科学中长期存在的问题之一。虽然已知平均晶粒尺寸如何随退火而变化，但对晶界特征分布、织构和晶粒形状的演变知之甚少。本研究的主要结论是，了解了晶界性能以及晶界性能随晶界结晶学的变化规律，就有可能预测晶粒生长过程中微观结构的变化。将采用观察、模拟、比较和校正的连续反馈循环，目的是为晶粒生长建立准确的预测模型。研究将集中在具有一系列各向异性晶界特性的材料上。铁素体铁具有最具各向同性的性质。钛酸锶的晶界性能主要与晶界面取向有关。镍的晶界性能在晶格取向和晶界面取向方面都具有各向异性。本研究中三维微观结构演化的研究将为验证各向异性晶界特征分布和晶粒生长停滞的发展机制提供可能。

NON-TECHNICAL DESCRIPTION: Nearly all man-made solids are made up of many small crystals referred to as grains. The sizes of these grains and the way that they are attached - characteristics determined when the material is made - influence many of the solid's properties. Existing models for the evolution of the grains during processing fail to predict observed outcomes. Because of the complexity of the problem, it is not even obvious that it is possible to make accurate predictions of how grains evolve during processing. The research will test the hypothesis that it is possible to predict the evolution of the grains within a material if information about the properties of the interfaces between the grains is included. The research will couple simulations with newly developed experimental techniques to test the hypothesis. Methods will be employed to identify where current models are insufficient, how they can be improved, and the degree to which it will be possible to predict grain evolution. The broader impact of this research is that the ability to predict how grains change during processing will make it possible to avoid trial and error experimentation and develop improved materials more quickly and at a lower cost.TECHNICAL DESCRIPTION: Predicting exactly how microstructures evolve during thermal annealing is one of the longstanding problems in materials science. While it is known how the average grain size will change with annealing, very little is known about the evolution of the grain boundary character distribution, the texture, and the grain shape. The main assertion of this research is that with knowledge of the grain boundary properties and how the properties vary with the crystallography of the grain boundary, it will be possible to predict how the microstructure will change during grain growth. A continuous feedback cycle of observations, simulation, comparison, and correction will be employed with the objective of creating accurate, predictive models for grain growth. The research will focus on materials with a range of anisotropic grain boundary properties. Ferritic iron has the most isotropic properties. The grain boundary properties of strontium titanate vary mostly with respect to grain boundary plane orientation. The grain boundary properties of nickel are anisotropic with respect to both lattice misorientation and grain boundary plane orientation. The studies of three-dimensional microstructure evolution in this research will make it possible to test proposed mechanisms for the development of anisotropic grain boundary character distributions and grain growth stagnation.