Abstract
Great progress has been made in understanding the atomic structure of metallic glasses, but there is still no clear connection between atomic structure and glass-forming ability. Here we give new insights into perhaps the most important question in the field of amorphous metals: how can glass-forming ability be predicted from atomic structure? We give a new approach to modelling metallic glass atomic structures by solving three long-standing problems: we discover a new family of structural defects that discourage glass formation; we impose efficient local packing around all atoms simultaneously; and we enforce structural self-consistency. Fewer than a dozen binary structures satisfy these constraints, but extra degrees of freedom in structures with three or more different atom sizes significantly expand the number of relatively stable, ‘bulk' metallic glasses. The present work gives a new approach towards achieving the long-sought goal of a predictive capability for bulk metallic glasses.
Highlights
Great progress has been made in understanding the atomic structure of metallic glasses, but there is still no clear connection between atomic structure and glass-forming ability
The dense random packing (DRP) model was introduced independently to describe the structure of monatomic liquids[2,3,4]
Known to exist in metallic glasses. It could not explain the medium-range order (MRO) found soon after the stereo-chemically defined (SCD) model was introduced[9], there was never a satisfying description of how efficiently packed clusters were arranged to avoid packing frustration[10], and it could not explain the full range of atom sizes and concentrations that produced metallic glasses
Summary
Great progress has been made in understanding the atomic structure of metallic glasses, but there is still no clear connection between atomic structure and glass-forming ability. These curves hold constant the packing efficiency (Pi) and the total number of atoms in the first shell of i-centred clusters (Zi,tot). These are the only points in binary size-composition space where packing is efficient around both atoms simultaneously.
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