Observation of Al41Sm5: new evidence for structural hierarchy in Al-Sm alloys

TL;DR

This study uncovers the structure of a metastable Al41Sm5 phase in Al-Sm alloys, revealing structural hierarchy's role in phase selection during devitrification, using a genetic algorithm to analyze amorphous-to-crystalline transformations.

Contribution

The paper introduces a novel application of genetic algorithms to identify metastable phases and elucidates the structural hierarchy influencing phase formation in Al-Sm alloys.

Findings

Discovered the structure of Al41Sm5 phase.

Identified multiple large-unit-cell phases during devitrification.

Demonstrated the importance of structural hierarchy in phase selection.

Abstract

Using an effective genetic algorithm, we uncover the structure of a metastable Al41Sm5 phase that supplements its family sharing similar short-range orders. The phase evolves upon heating an amorphous Al-9.7at.%Sm ribbon, produced by melt-spinning. The dynamical phase selection is discussed with respect to the structural connections between the short-range packing motifs in the amorphous precursor and those observed in the selected phases. The phase elucidated here is one of several newly discovered large-unit-cell phases found to form during devitrification from the glass in this binary system, further illustrating the power and efficiency of our approach, the important role of structural hierarchy in phase selection, and the richness of the metastable phase landscape accessible from the glassy structure.