Grain Boundary Segregation Transitions and Critical Phenomena in Binary Regular Solutions: A Systematics of Complexion Diagrams with Universal Characters

作     者：Zhou, Naixie Hu, Chongze Luo, Jian 

作者机构：Department of NanoEngineering Program of Materials Science and Engineering University of California San Diego United States 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2021年

核心收录：

主　　题：Grain boundaries 

摘      要：A systematics of grain boundary (GB) segregation transitions and critical phenomena has been derived to expand the classical GB segregation theory. Using twist GBs as an example, this study uncovers when GB layering vs. prewetting transitions should occur and how they are related to one another. Moreover, a novel descriptor, normalized segregation strength (seg), is introduced. It can represent several factors that control GB segregation, including strain and bond energies, as well as misorientation for small-angle GBs (in a mean-field approximation), which had to be treated separately in prior models. In a strong segregation system with a large seg, first-order layering transitions occur at low temperatures and become continuous above GB roughing temperatures. With reducing seg, the layering transitions gradually merge and finally lump into prewetting transitions without quantized layer numbers, akin to Cahn’s critical-point wetting model. Furthermore, GB complexion diagrams with universal characters are constructed as the GB counterpart to the classical exemplar of Pelton-Thompson regular-solution binary bulk phase diagrams. © 2021, CC BY.