Fig. 2: Mechanism of Ti2AlC MAX phase formation.
From: Large-scale conformal synthesis of one-dimensional MAX phases
a Schematics of the in-situ crystalline evolution during the formation of 1D-Ti2AlC. The blue spheres represent Ti atoms, orange spheres represent Al atoms, black spheres represent carbon atoms, and the squares represent carbon vacancies. The symbols of other spheres in this figure are consistent with the description above. b TEM image of selected area in the obtained nanofiber from 900 °C with dwell time 0.5 hours presents the relevant products, indicating the Ti2AlC crystals nucleated between TiCx domain and the diffused TiAl phase with their corresponding FFT images displayed. c The HRTEM results of (i) disordered (TiAl)Cx, (ii) re-ordering (TiAl)Cx, to (iii) disordered Ti2AlC, and ordered Ti2AlC reveals the in-situ reconstruction from (TiAl)Cx to Ti2AlC, which is the detailed process from orange region in a. d XRD patterns of the products from 800°C to 1100 °C. e Calculated Gibbs free energy of possible reactions from 500 °C to 1300 °C. f, DSC and TG curve of a mixture of Ti, Al and TiC nanofibers in the presence of the KCl–NaCl eutectic composition salt under the protection of Ar gas at a rate of 10 °C/min, the colored shades represent the different stages. g Calculated phase diagrams of reactants from 900 °C at 0.05 atm pressure, where the blue regions shown the products containing Ti2AlC in this phase diagram. Source data are provided as a Source Data file.
