Notation for chemical arrangements in alloys

Since there is no proper method to classify arrangements of atoms of different elements—chemical arrangements—the atomic structure of liquid and glassy alloys is hidden under a veil of mystery. Here we present a method to represent chemical arrangements by unique number sequences, which can be readily classified. This method paves the way for statistically studying chemical arrangements and thus provides further insight into the physics of disordered materials. As a demonstration, we apply it to uncover possible chemical arrangements responsible for preventing crystallization of a supercooled liquid alloy.