On the stochastic phase stability of Ti₂AlC-Cr₂AlC

The quest towards expansion of the M _n+1AX _n design space has been accelerated with the recent discovery of several solid solution and ordered phases involving at least two M _n+1AX _n end members. Going beyond the nominal M _n+1AX _n compounds enables not only fine tuning of existing properties but also entirely new functionality. This search, however, has been mostly done through painstaking experiments as knowledge of the phase stability of the relevant systems is rather scarce. In this work, we report the first attempt to evaluate the finite-temperature pseudo-binary phase diagram of the Ti₂AlC-Cr₂AlC via first-principles-guided Bayesian CALPHAD framework that accounts for uncertainties not only in ab initio calculations and thermodynamic models but also in synthesis conditions in reported experiments. The phase stability analyses are shown to have good agreement with previous experiments. The work points towards a promising way of investigating phase stability in other MAX Phase systems providing the knowledge necessary to elucidate possible synthesis routes for M _n+1AX _n systems with unprecedented properties.