Review of grain boundary complexion engineering: Know your boundaries

Abstract

Grain boundary structure-property relationships influence bulk performance and, therefore, are an important criterion in materials design. Materials scientists can generate different grain boundary structures by changes in temperature, pressure, and chemical potential because interfaces attain their own equilibrium states, known as complexions. Complexions undergo first-order transitions by changes in thermodynamic variables, which results in discontinuous changes in properties.Grain boundary complexion engineering is introduced in this paper as a method for controlling complexion transitions to improve material performance. This International Conference on Sintering 2017 lecture describes the tools for grain boundary complexion engineering: complexion equilibrium and time-temperaturetransformation (TTT) diagrams. These tools can be implemented in processing design to tailor grain boundary properties, including grain boundary mobility.While impactful, these diagrams are often limited in scope because they are currently empirically derived. This article discusses how measurement techniques can be combined with data analytical methods to build mechanistically derived complexion equilibrium and TTT diagrams.

Effect of Eu‐doping and grain boundary plane on complexion transitions in MgAl2O4

“…The equilibrium structure and composition of a grain boundary have been coined a complexion 5 . The realization that grain boundaries have equilibrium states and transition has inspired the field of study termed grain boundary complexion engineering (GBCE) 6 …”

“…5 The realization that grain boundaries have equilibrium states and transition has inspired the field of study termed grain boundary complexion engineering (GBCE). 6 GBCE exploits grain boundary complexion transitions to induce sudden changes in grain boundary properties (e.g., grain boundary mobility) as well as bulk material properties (e.g., toughness) and behavior (e.g., grain growth). 7 In general, tools are needed to predict and guide complexion…”

Shear wave generation by mode conversion in picosecond ultrasonics: Impact of grain orientation and material properties

“…Modification and characterization of the physical and chemical properties of grain boundaries have been widely applied to improving polycrystalline material properties 1 . A number of studies have focused on correlating grain boundary characters to bulk properties 1,2 .…”

“…Modification and characterization of the physical and chemical properties of grain boundaries have been widely applied to improving polycrystalline material properties 1 . A number of studies have focused on correlating grain boundary characters to bulk properties 1,2 . For example, the character distribution of grain boundaries was discovered to be responsible for the exhibition of ferromagnetism in textured ZnO thin film 3 .…”

Recent Developments of ζ-factor Microanalysis and Its Application to Armor Ceramics

“…The diffusion couple was used to determine maximum Si solubility in the boron carbide lattice and the consequential changes to B/C stoichiometry and Si segregation behavior. Furthermore, if sufficient Si segregation was to occur, it was hypothesized that thick nanolayer complexions would form [8], thereby weakening grain boundaries and improving fracture resistance. Figure 2a shows a backscatter electron micrograph of the diffusion couple and the locations where thin specimens were extracted for ζ-factor quantification.…”