Volume conservation in bulk metallic glasses

Abstract

We report that the excess molar volumes of mixing for ~30 metalloid-free bulk metallic glasses (BMGs) are essentially zero, indicating that the original volumes of "mechanically mixed" constituent elemental metals are conserved after glass formation. This is attributed to the lack of solute-solute bonds and the ideal-mixing nature of solvent-solute bonding upon amorphization. The hard-sphere atomic packing fractions of most of these BMGs are found to be ~0.74, comparable to the maximum packing efficiency for close-packed structures. These findings provide a new perspective for understanding amorphous structures.