Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

Chen, Hao; Levitas, Valery I.; Popov, Dmitry; Velisavljevic, Nenad

doi:10.1038/s41467-022-28604-1

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…For Ta-based samples, it has been shown that under such severe plastic deformation processes, a phase transition from the BCC crystal structure to the FCC or HCP crystal structure occurs by breaking the bonds of the BCC atoms 38 . It is worth noting that the mentioned process is not a unique phenomenon for BCC metals and similar trends have also been reported in other crystalline structures at extreme deformation regimes 39 – 41 .…”

Section: Introductionsupporting

confidence: 84%

Strain-rate-dependent plasticity of Ta-Cu nanocomposites for therapeutic implants

Kardani,

Montazeri,

Urbassek

2023

Sci Rep

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Recently, Ta/Cu nanocomposites have been widely used in therapeutic medical devices due to their excellent bioactivity and biocompatibility, antimicrobial property, and outstanding corrosion and wear resistance. Since mechanical yielding and any other deformation in the patient's body during treatment are unacceptable in medicine, the characterization of the mechanical behavior of these nanomaterials is of great importance. We focus on the microstructural evolution of Ta/Cu nanocomposite samples under uniaxial tensile loading conditions at different strain rates using a series of molecular dynamics simulations and compare to the reference case of pure Ta. The results show that the increase in dislocation density at lower strain rates leads to the significant weakening of the mechanical properties. The strain rate-dependent plastic deformation mechanism of the samples can be divided into three main categories: phase transitions at the extreme strain rates, dislocation slip/twinning at lower strain rates for coarse-grained samples, and grain-boundary based activities for the finer-grained samples. Finally, we demonstrate that the load transfer from the Ta matrix to the Cu nanoparticles via the interfacial region can significantly affect the plastic deformation of the matrix in all nanocomposite samples. These results will prove useful for the design of therapeutic implants based on Ta/Cu nanocomposites.

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Section: Introductionsupporting

confidence: 84%

Strain-rate-dependent plasticity of Ta-Cu nanocomposites for therapeutic implants

Kardani,

Montazeri,

Urbassek

2023

Sci Rep

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“…As shown in Figure 3e, we can observe the apparent differences obtained from the metallic precursors, partly because of the wrinkles or cracks that appeared under pressure. The formation of cracks or wrinkles is associated with strong local stress concentration, 50 and these cracks or wrinkles do not disappear with the reversibility of phase transition. Next, we turn to the temperature effect on the transition behavior from Si-II to Si-XII and Si-III during the decompression process, as shown in Figure 4.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Structural Modulation and BC8 Enrichment of Silicon via Dynamic Decompression

Du,

Dong

et al. 2024

J. Phys. Chem. C

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The modern very large-scale integration systems based on silicon semiconductors are facing unprecedented challenges especially when transistor feature size lowers further, due to the excruciating tunneling effect and thermal management. Besides the common diamond cubic silicon, numerous exotic silicon allotropes with outstanding properties can emerge under high pressure, such as the metastable BC8 and metallic β-tin structures. Despite much effort on the controlled synthesis in experiment and theory, the effective approach to rationally prepare Si phases with desired purity is still lacking, and their transition mechanism remains controversial. Herein, we systematically investigated the complicated structural transformations of Si under extreme conditions and efficiently enriched the BC8-Si phase via an ultraslow decompression strategy. The splendid purity of BC8-Si was achieved up to ∼95%, evidently confirmed by Raman spectroscopy and synchrotron X-ray diffraction. We believe that these results can shed light on the controlled preparation of Si metastable phases and their potential applications in nanoelectronics.

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“…158). Large transformation strains, typical for PTs in Si, graphite, and BN, may lead to very non-traditional nanostructures 159) and change the microstructure formation principles. However, none of these works includes plasticity, which is required for application to strain-induced PTs.…”

Section: Plastic Strain-induced Reduction Of Phase Transformation Pre...mentioning

confidence: 99%

Recent <i>In Situ</i> Experimental and Theoretical Advances in Severe Plastic Deformations, Strain-Induced Phase Transformations, and Microstructure Evolution under High Pressure

Levitas

2023

Mater. Trans.

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Severe plastic deformations (SPD) under high pressure, mostly by high-pressure torsion, are employed for producing nanostructured materials and stable or metastable high-pressure phases. However, they were studied postmortem after pressure release. Here, we review recent in situ experimental and theoretical studies of coupled SPD, strain-induced phase transformations (PTs), and microstructure evolution under high pressure obtained under compression in diamond anvil cell or compression and torsion in rotational diamond anvil cell. The utilization of x-ray diffraction with synchrotron radiation allows one to determine the radial distribution of volume fraction of phases, pressure, dislocation density, and crystallite size in each phase and find the main laws of their evolution and interaction. Coupling with the finite element simulations of the sample behavior allows the determination of fields of all components of the stress and plastic strain tensors and volume fraction of high-pressure phase and provides a better understanding of ways to control occurring processes. Atomistic, nanoscale and scale-free phase-field simulations allow elucidation of the main physical mechanisms of the plastic strain-induced drastic reduction in phase transformation pressure (by one to two orders of magnitude), the appearance of new phases, and strain-controlled PT kinetics in comparison with hydrostatic loading. Combining in situ experiments with multiscale theory potentially leads to the formulation of methods to control strain-induced PT and microstructure evolution and designing economic synthetic paths for the defect-induced synthesis of desired high-pressure phases, nanostructures, and nanocomposites.

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Nontrivial nanostructure, stress relaxation mechanisms, and crystallography for pressure-induced Si-I → Si-II phase transformation

Cited by 6 publications

References 24 publications

Strain-rate-dependent plasticity of Ta-Cu nanocomposites for therapeutic implants

Strain-rate-dependent plasticity of Ta-Cu nanocomposites for therapeutic implants

Structural Modulation and BC8 Enrichment of Silicon via Dynamic Decompression

Recent <i>In Situ</i> Experimental and Theoretical Advances in Severe Plastic Deformations, Strain-Induced Phase Transformations, and Microstructure Evolution under High Pressure

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