Thermal and Mechanical Properties of the Ti2AlX (X = C, N) MAX Phases: A DFT Study

The aim of the present work is to provide new insights on how the nitrogen concentration affects the stability, thermal, and mechanical properties of the Ti2AlC MAX Phase. To this purpose, the DFT-based pseudopotential method combined with the Debye Quasi-harmonic model is applied. The results display a strong dependency of the studied properties on the nitrogen concentration; indeed, the stability and rigidity of the Ti2AlC alloys are substantially improved by nitrogen insertion even at elevated temperatures. Ti2AlC, Ti2AlN, and Ti2AlC0.5N0.5 are brittle and dynamically stable at 0 K with their hexagonal structures. The results are deeply discussed in light of the available theoretical and experimental results.