Stress induced atomic-scale damage and relaxation in bulk metallic glasses

AbstractBulk metallic glasses exhibit confined low and high frequency vibrational properties resulting from the significant bon and topological disorder occuring at the atomic scale. The precise nature of the low frequency modes and how they are influenced by local atomic structure remains unclear. Using standard harmonic analysis, the current work investigates various aspects of the problem by diagonalizing the Hessian of atomistic samples derived from molecular dynamics simulations via a model binary Lennard Jones pair potential.

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Effect of manipulating atomic scale heterogeneity on plasticity in Mg-based bulk metallic glasses

Intermetallics ◽

10.1016/j.intermet.2010.01.025 ◽

2010 ◽

Vol 18 (10) ◽

pp. 1867-1871 ◽

Cited By ~ 6

Author(s):

E.S. Park ◽

D.H. Kim

Keyword(s):

Metallic Glasses ◽

Bulk Metallic Glasses ◽

Atomic Scale ◽

Scale Heterogeneity

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Short Range Chemical Ordering in Bulk Metallic Glasses

MRS Proceedings ◽

10.1557/proc-644-l1.3 ◽

2000 ◽

Vol 644 ◽

Author(s):

P. A. Sterne ◽

P. Asoka-Kumar ◽

J. H. Hartley ◽

R. H. Howell ◽

T.G. Nieh ◽

...

Keyword(s):

Positron Annihilation ◽

Metallic Glasses ◽

Bulk Metallic Glasses ◽

Critical Density ◽

Positron Annihilation Spectroscopy ◽

Atomic Scale ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Chemical Ordering ◽

Open Volume

AbstractWe provide direct experimental evidence for a non-random distribution of atomic constituents in Zr-based multi-component bulk metallic glasses using positron annihilation spectroscopy. The Ti content around the open-volume regions is significantly enhanced at the expense of Cu and Ni, indicating that Cu and Ni occupy most of the volume bounded by their neighboring atoms while Ti and Zr are less closely packed and more likely to be associated with open-volume regions. Temperature-dependent measurements indicate the presence of at least two different characteristic sizes for the open volume regions. Measurements on hydrogen- charged samples show that the larger open-volume regions can be filled by hydrogen up to a critical density. Beyond this critical density, local atomic-scale open-volume damage is created in the sample to accommodate additional hydrogen. The onset of this local damage in positron annihilation data coincides with the onset of volume expansion in X-ray diffraction data.

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Substantially enhanced plasticity of bulk metallic glasses by densifying local atomic packing

Nature Communications ◽

10.1038/s41467-021-26858-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yuan Wu ◽

Di Cao ◽

Yilin Yao ◽

Guosheng Zhang ◽

Jinyue Wang ◽

...

Keyword(s):

Plastic Deformation ◽

Metallic Glasses ◽

Room Temperature ◽

Bulk Metallic Glasses ◽

Atomic Scale ◽

Structure Property ◽

Atomic Packing ◽

Structure Property Relationships ◽

New Strategy ◽

Structural Fluctuations

AbstractIntroducing regions of looser atomic packing in bulk metallic glasses (BMGs) was reported to facilitate plastic deformation, rendering BMGs more ductile at room temperature. Here, we present a different alloy design approach, namely, doping the nonmetallic elements to form densely packed motifs. The enhanced structural fluctuations in Ti-, Zr- and Cu-based BMG systems leads to improved strength and renders these solutes’ atomic neighborhoods more prone to plastic deformation at an increased critical stress. As a result, we simultaneously increased the compressive plasticity (from ∼8% to unfractured), strength (from ∼1725 to 1925 MPa) and toughness (from 87 ± 10 to 165 ± 15 MPa√m), as exemplarily demonstrated for the Zr20Cu20Hf20Ti20Ni20 BMG. Our study advances the understanding of the atomic-scale origin of structure-property relationships in amorphous solids and provides a new strategy for ductilizing BMG without sacrificing strength.

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