Grain boundary segregation transitions and critical phenomena in binary regular solutions: A systematics of complexion diagrams with universal characters

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