High-purity synthesis of Ti2MAlC2 (M = Nb, Ta, W) and Ti2HEAlC2 (HE = Ti, V, Zr, Nb, Hf, Ta, W) novel MAX phase ceramics

MAX phase ceramics, as a family of ternary layered ceramics, have received a lot of attention in the past decade due to their potential as precursors for two-dimensional transition metal carbides. However, due to complex multi-component metallurgical reactions, multicomponent MAX phase ceramics have always faced difficulties in purification and homogenization. This paper identifies a new strategy for synthesizing multicomponent MAX phase ceramics that can eliminate these synthesis difficulties. This path utilizes low-temperature (below 1000°C) stable Ti 2 AlC and carbide powder as initial materials to simplify complex multi-component reactions into a one-step reaction, successfully achieving high purity and precise doping ratio. As an example, four novel doped MAX phase ceramics, Ti 2 MAlC 2 (M = Nb, Ta, W) and Ti 2 HEAlC 2 (HE = 1/7Ti, 1/7V, 1/7Zr, 1/7Nb, 1/7Hf, 1/7Ta, 1/7 W) were successfully synthesized using this method. This dynamic-based design, on one hand, simplifies the reaction mechanism to make purification easier, and on the other hand, the concentrated release of entropy during the reaction process promotes phase transition and related element homogenization.