![]() ![]() For example, a point defect corresponds to a missing or an extra atom in the lattice and a line defect is the termination of an extra plane of atoms, which locally disrupts the lattice structure. 15 In this article, in an attempt to provide a basis for GB structure–property relationships, we present an automated algorithm to compute the three-dimensional (3D) polyhedral unit model for describing the atomistic structure of GBs in fcc metallic systems.ĭefects in crystalline materials may be visualized as local disruptions in the symmetric arrangement of atoms. 13, 14 Even from a modeling perspective, the ability to develop reliable GB structure–property relationships has been identified as one of the biggest obstacles in developing robust bottom-up models for predicting polycrystalline material behavior. ![]() However, there remain fundamental challenges in our ability to compute the structure–property relationships of individual interfaces and to analyze the influence of a collection of grain boundaries (GBs) on the macroscopic properties of materials. Grain boundaries influence a wide array of properties in polycrystalline materials, 1 including diffusivity, 2, 3, 4 conductivity, 5, 6, 7 intergranular cracking, 8 corrosion resistance, 9, 10 embrittlement 11, 12 etc. The polyhedral unit model is also applicable to a wide array of material systems as the proposed algorithm is not limited by the underlying lattice structure. ![]() We anticipate that this technique will serve as a powerful tool in the analysis of grain boundary structure. Since the obtained polyhedral units circumscribe the voids present in the structure, such a description provides valuable information concerning segregation sites within the grain boundary. The polyhedral unit model is robust enough to capture the structure of high-Σ, mixed character interfaces and, hence, provides a geometric tool for comparing grain boundary structures across the five-parameter crystallographic phase-space. A point-pattern matching algorithm is also provided for quantifying the distortions of the observed grain boundary polyhedral units. In this article, we propose an algorithm that can partition the atomic structure into a connected array of three-dimensional polyhedra, and thus, present a three-dimensional polyhedral unit model for grain boundaries. While the atomic structure in disordered systems has been a topic of interest for many decades, geometrical analyses of grain boundaries has proven to be particularly challenging because of the wide range of structures that are possible depending on the underlying macroscopic crystallographic character. As a first step in analyzing such relationships, we present a polyhedral unit model to classify the geometrical nature of atomic packing along grain boundaries. One of the biggest challenges in developing truly bottom-up models for the performance of polycrystalline materials is the lack of robust quantitative structure–property relationships for interfaces. ![]()
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