Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Bulk metallic glasses (BMGs) are amorphous alloys with unique properties.
• Understanding the atomic structure of BMGs is crucial for predicting their performance.
• Mg-Zn-Ca alloys are investigated for biomedical applications due to their biocompatibility.

Purpose of the Study:

• To determine the atomic structure of five Mg-Zn-Ca bulk metallic glasses with varying compositions.
• To correlate atomic structure with in vitro implantation behavior.
• To evaluate the applicability of the efficient cluster packing model for these systems.

Main Methods:

• Classical molecular dynamics simulations were employed to model atomic structures.
• Neutron diffraction experiments were conducted for experimental validation.
• Analysis included bond lengths, total correlation functions, and Voronoi polyhedra distributions.

Main Results:

• Excellent agreement was achieved between simulated and experimental structures.
• Compositional changes had minimal impact on overall bond lengths and total correlation functions.
• Zn-Ca bonding characteristics evolved with composition, showing a shift from avoidance to preference, correlating with implantation behavior changes.
• Voronoi polyhedra distributions broadened with increasing zinc content.
• The efficient cluster packing model was found unsuitable for describing these Mg-Zn-Ca BMGs.

Conclusions:

• The atomic structure of Mg-Zn-Ca BMGs is sensitive to composition, particularly in Zn-Ca bonding.
• Composition-dependent structural changes, especially in Zn-Ca interactions, may underlie observed differences in in vitro implantation behavior.
• The findings provide insights into the structure-property relationships of Mg-based BMGs for potential applications.