Liquid-like interface complexion: From activated sintering to grain boundary diagrams

This article reviews recent experimental and theoretical results that elucidate the mysterious subsolidus activated sintering mechanism. A related new concept of liquid-like interface complexion and its broad applications in comprehending microstructural evolution and materials properties are discussed. A recently proposed thermodynamic model is discussed and further elaborated with new analyses that have not been published before. A long-range scientific goal is to develop quantitative and predictive grain boundary diagrams as a new tool for realizing predictable fabrication of materials by design.