Physical origins and empirical scaling relations for the structural, mechanical, and thermal properties of MAX phases: A high-throughput ab-initio study

While the diverse chemistry of the MAX phases enables property tunability, it also challenges targeted design. To overcome the current situation of fragmented data and some unreliable predictions, high-throughput first-principles calculations were performed on all 103 synthesized MAX phases, and a rigorously validated property database—benchmarked against experiments—was established, covering lattice parameters, elastic moduli, fracture toughness, heat capacity, and thermal expansion. Strong statistical relationships exist among elastic constants. Conventional toughness indicators are inadequate for the true toughness prediction, whereas the bond-stiffness model shows high reliability. Moreover, simple and physically transparent scaling laws, rooted in the Dulong–Petit limit and Grüneisen theory, were derived for heat capacity and thermal expansion. The resulting database and models provide crucial insights and a reliable platform for accelerating the design and future application of MAX phases.