Effects of minor alloying on the mechanical properties of Al based metallic glasses

Minor alloying is widely used to control mechanical properties of metallic glasses (MGs). The present understanding of how a small amount of alloying element changes strength is that the additions lead to more efficient packing of atoms and increased local topological order, which then increases the...

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Bibliographic Details
Published in:Journal of alloys and compounds 2021-02, Vol.854, p.157266, Article 157266
Main Authors: Jambur, V., Tangpatjaroen, C., Xi, J., Tarnsangpradit, J., Gao, M., Sheng, H., Perepezko, J.H., Szlufarska, I.
Format: Article
Language:English
Subjects:
Ab initio calculations
Alloying effects
Alloying elements
Aluminum
Amorphous materials
Bonding strength
Chemical bonds
Hardness
Mechanical analysis
Mechanical properties
Metallic glasses
Molecular dynamics
Nanoindentation
Plastic deformation
Samarium base alloys
Shear strength
Strengthening
Topology
Transition metal alloys
Transition metals
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Summary:Minor alloying is widely used to control mechanical properties of metallic glasses (MGs). The present understanding of how a small amount of alloying element changes strength is that the additions lead to more efficient packing of atoms and increased local topological order, which then increases the barrier for shear transformations and the resistance to plastic deformation. Here, we discover that minor alloying can improve the strength of MGs by increasing the chemical bond strength alone and show that this strengthening is distinct from changes in topological order. The results were obtained using Al–Sm based MGs minor alloyed with transition metals (TMs). The addition of TMs led to an increase in the hardness of the MGs which, however, could not be explained based on changes in the topological ordering in the structure. Instead we found that it was the strong bonding between TM and Al atoms which led to a higher resistance to shear transformation that resulted in higher strength and hardness, while the topology around the TM atoms had no influence on their mechanical response. This finding demonstrates that the effects of topology and chemistry on mechanical properties of MGs are independent of each other and that they should be understood as separate, sometimes competing mechanisms of strengthening. This understanding lays a foundation for design of MGs with improved mechanical properties. •Minor alloying with transition metals leads to an increase hardness of Al–Sm metallic glasses.•Changes in topological short-range order cannot explain the increase in hardness.•Hardening is due to strong bonding between Al and transition metals which increases resistance to local shear transformations.•Effects of topology and chemistry on mechanical properties of metallic glasses can be independent of each other.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2020.157266