Origins of size effects in initially dislocation-free single-crystal silver micro- and nanocubes

Griesbach, Claire; Jeon, Seog‐Jin; Rojas, David Funes; Ponga, Mauricio; Yazdi, Sadegh; Pathak, Siddhartha; Mara, Nathan A.; Thomas, Edwin L.; Thevamaran, Ramathasan

doi:10.1016/j.actamat.2021.117020

Cited by 18 publications

(5 citation statements)

References 46 publications

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“…A similar behavior has been reported in the compression of defect-free Mo alloy single-crystal micropillars . This common phenomenon observed in micro/nanosized crystals is usually associated with dislocation nucleation and movement in perfect microparticles/cubes. − ,− Furthermore, it has been found that in the elastic stage, the load–displacement curve of the microparticles follows either a linear or a power-law response, which originates from the difference in the local contact between the flat indenter and the microparticles determined by FEA simulations and theoretical analysis (supplementary section S3).…”

Section: Resultssupporting

confidence: 70%

“…26−30 Deformation mechanisms of dislocation nucleation controlled (or dislocation starvation) 31 and source-controlled 32,33 are revealed. However, it has been considered that FIB usually produces a surface damage layer with a thickness of 10−20 nm, 34 which complicates the mechanism understanding. 33 It was observed that much higher yield strength can be achieved in smooth spherical nanoparticles because the passivated smooth surface is expected to reduce the possibility of surface dislocation nucleation.…”

Section: Introductionmentioning

confidence: 99%

“…In the past decades, the focused ion beam (FIB) technique has been widely used to fabricate micropillars, based on which “the smaller the stronger” has been observed in a wide range of material classes, including metals, ,− ceramics, − semiconductors, − and alloys. − Deformation mechanisms of dislocation nucleation controlled (or dislocation starvation) and source-controlled , are revealed. However, it has been considered that FIB usually produces a surface damage layer with a thickness of 10–20 nm, which complicates the mechanism understanding . It was observed that much higher yield strength can be achieved in smooth spherical nanoparticles because the passivated smooth surface is expected to reduce the possibility of surface dislocation nucleation. − Recently, by applying the solid-state dewetting method and carefully controlling the defects in metal micro/nanoparticles, evidence of source-controlled plasticity with a theoretical strength limit is provided .…”

Section: Introductionmentioning

confidence: 99%

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Weak Size-Dependent Strength and Extreme Plastic Deformation of Single Crystal Cu Microparticles

Lu,

Pan,

Fang

et al. 2024

J. Phys. Chem. C

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Single crystal Cu microparticles with varied sizes and good crystallinity were batch-fabricated by a flash arc synthesis (FAS) method. The size and extreme plastic deformation-dependent mechanical behaviors of Cu microparticles were investigated through in situ mechanical tests under scanning electron microscopy (SEM). It is noted that the Cu microparticles exhibit near theoretical strength at much larger sizes by comparison with reported values, accompanied by the weak size effect on strength, which we attribute to the high quality of the prepared Cu microparticles. Besides, the hardness of precompressed Cu microparticles increases sharply with the increase of the residual strain, which we attribute to the obstruction of dislocation movement by the drastically increased contact interfaces during extreme plastic deformation and the high hydrostatic pressure induced by friction at the contact interfaces. Then, an extended Taylor hardening model is developed to quantify the residual strain-dependent hardness.

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Section: Resultssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Weak Size-Dependent Strength and Extreme Plastic Deformation of Single Crystal Cu Microparticles

Lu,

Pan,

Fang

et al. 2024

J. Phys. Chem. C

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“…Their reliability in these applications depends on their stability and mechanical behavior and thus requires a clear understanding of their deformation under load. It is well established that decreasing the size of a structure increases its strength by reducing or eliminating defects and defect sources, giving rise to the “smaller-is-stronger” trend. − Below the size scale of a few hundred nanometers, surface nucleation of dislocations becomes the dominant deformation process in pristine nanostructures − as well as twinned and multimetallic structures, resulting in a size-independent high-strength plateau. ,− This surface nucleation has been extensively studied in nanowires and can be described as a stress-dependent thermally activated process, where the activation barrier is highly sensitive to the surface state, with surface steps and terraces lowering the yield strength. − …”

Section: Introductionmentioning

confidence: 99%

Size-Dependent Role of Surfaces in the Deformation of Platinum Nanoparticles

et al. 2023

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The mechanical behavior of nanostructures is known to transition from a Hall-Petch-like “smaller-is-stronger” trend, explained by dislocation starvation, to an inverse Hall-Petch “smaller-is-weaker” trend, typically attributed to the effect of surface diffusion. Yet recent work on platinum nanowires demonstrated the persistence of the smaller-is-stronger behavior down to few-nanometer diameters. Here, we used in situ nanomechanical testing inside of a transmission electron microscope (TEM) to study the strength and deformation mechanisms of platinum nanoparticles, revealing the prominent and size-dependent role of surfaces. For larger particles with diameters from 41 nm down to approximately 9 nm, deformation was predominantly displacive yet still showed the smaller-is-weaker trend, suggesting a key role of surface curvature on dislocation nucleation. For particles below 9 nm, the weakening saturated to a constant value and particles deformed homogeneously, with shape recovery after load removal. Our high-resolution TEM videos revealed the role of surface atom migration in shape change during and after loading. During compression, the deformation was accommodated by atomic motion from lower-energy facets to higher-energy facets, which may indicate that it was governed by a confined-geometry equilibration; when the compression was removed, atom migration was reversed, and the original stress-free equilibrium shape was recovered.

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“…The statistical likelihood for dislocation interactions decreases in nanoscale samples due to decreased sample volume and increased dislocation annihilation at free surfaces. This has led to minimal strain hardening and large slip events in defect-free fcc Ag, , Cu, Au@Ag, and Ni 3 Al nanocubes. In contrast, the large strain hardening rate and presence of dislocation loops in compressed Al nanocubes indicate that dislocation interactions occur in the small sample volume.…”

mentioning

confidence: 99%

Extraordinary Strain Hardening from Dislocation Loops in Defect-Free Al Nanocubes

et al. 2022

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The complex interaction of crystalline defects leads to strain hardening in bulk metals. Metals with high stacking fault energy (SFE), such as aluminum, tend to have low strain hardening rates due to an inability to form stacking faults and deformation twins. Here, we use in situ scanning electron microscopy (SEM) mechanical compressions to find that colloidally synthesized defect-free 114 nm Al nanocubes combine a high linear strain hardening rate of 4.1 GPa with a high strength of 1.1 GPa. These nanocubes have a 3 nm selfpassivating oxide layer that has a large influence on mechanical behavior and the accumulation of dislocation structures. Postcompression transmission electron microcopy (TEM) imaging reveals stable prismatic dislocation loops and the absence of stacking faults. MD simulations relate the formation of dislocation loops and strain hardening to the surface oxide. These results indicate that slight modifications to surface and interfacial properties can induce enormous changes to mechanical properties in high SFE metals.

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Origins of size effects in initially dislocation-free single-crystal silver micro- and nanocubes

Cited by 18 publications

References 46 publications

Weak Size-Dependent Strength and Extreme Plastic Deformation of Single Crystal Cu Microparticles

Weak Size-Dependent Strength and Extreme Plastic Deformation of Single Crystal Cu Microparticles

Size-Dependent Role of Surfaces in the Deformation of Platinum Nanoparticles

Extraordinary Strain Hardening from Dislocation Loops in Defect-Free Al Nanocubes

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