Study the formation of metastable crystalline phases from amorphous metallic systems with an integrated approach

An efficient genetic algorithm (GA) is integrated with experimental diffraction data to solve a metastable Al$_{\mathrm{20}}$Sm$_{\mathrm{4}}$ phase that evolves during rapid solidification of an amorphous Al-10{\%}Sm alloy produced by magnetron sputtering. The excellent match between calculated and experimental X-ray diffraction patterns confirms that this new phase appeared in the crystallization of the alloy. We discover the strong similarity of the underlying atomic structure between the amorphous alloy and this phase. Both phases share the same Sm-centered motif, providing a low-barrier pathway to form this Al$_{\mathrm{20}}$Sm$_{\mathrm{4\thinspace }}$phase in the glass matrix at low temperatures. Molecular dynamic simulations of crystal growth from the liquid phase predict the formation of disordered anti-site defects in the devitrified crystal.