Composite materials based on MAX phases and 2D MXenes

M_n+1A_nX (MAX) phases are a family of thermodynamically stable, layered, early transition metal carbides/nitrides, where n = 1, 2, or 3, M is an early transition metal, A is an A-group element (e.g., Al or Si), and X is C and/or N. Due to their atomically layered structure, MAX phases possess a unique combination of metallic and ceramic properties. They exhibit high thermal/electrical conductivity, mechanical strength, toughness, stiffness, oxidation resistance, and machinability. Their derived 2D counterparts, known as MXenes, are synthesized by selective etching and exfoliation of the metallic layer resulting in a diverse family of few-atom layer thick carbides or nitrides. These 2D materials exhibit metallic conductivity, hydrophilicity, and chemical stability, and have remarkable potential in various applications, including energy storage, catalysis, sensing, and electromagnetic shielding. The distinctive properties of MAX phases and MXenes make them prime candidates as constituents in composite materials.

In this talk, I will discuss the recent progress we made on fabrication and characterization of composite materials based on MAX and MXene integrated with traditional metals or ceramics. Among them are Al₂O₃ with few- and multi-layer Ti₃C₂T_x MXene, Ti₃AlC₂/TiC/Al₂O₃ composites formed in-situ, Ti₃AlC₂/W composites, Al reinforced with Ti₃SiC₂, and Si₃N₄ with Ti₂AlN addition. I will cover various phenomena related to the stability of MAX and MXene associated with high-temperature processing. Notable features discovered include the effects of high-energy milling on destabilization of MAX phases, preventing phase transformation of MXenes at high temperatures, and the reactions between MAX phases and metals/ceramics. In addition, the influence of the MAX/MXene components on various physical, electrical, and mechanical properties of the composite materials will be discussed.