MAX Phases as Nanolaminate Materials: Chemical Composition, Microstructure, Synthesis, Properties, and Applications

In recent years, MAX phases, a family of nanolaminate materials, have garnered tremendous research interest worldwide, due to the fact that they possess an excellent combination of both metallic and ceramic characteristics. The number of publications on MAX phases has experienced an almost exponential increase in the past decade. The main objective herein is to develop a comprehensive understanding of MAX phases, meanwhile presenting the recent progress and development of MAX phases. The Review starts with introducing the chemical composition of MAX phases, followed by reviewing the microstructure, which includes both the well‐known 211, 312, and 413 structures and the newly discovered out‐of‐plane ordered and in‐plane ordered structures. A wide range of synthesis methods are reviewed, such as traditional hot pressing, pressure‐less sintering, and recently reported substitutional solid–liquid reaction method. The chemical and physical properties of MAX phases are summarized. The potential fields of applications for MAX phases are surveyed, such as high‐temperature materials, nuclear materials, precursors for MXene, etc. In addition, an outlook for future research on MXX phases is also presented.