Shock-induced amorphization in silicon carbide

Zhao, Shiteng; Flanagan, Rachel; Hahn, Eric N.; Kad, Bimal K.; Remington, B. A.; Wehrenberg, Christopher; Cauble, R.; More, Karren L.; Meyers, Marc A.

doi:10.1016/j.actamat.2018.07.047

Cited by 83 publications

(35 citation statements)

References 30 publications

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“…In our case, the amorphous shear band is the primary driver of plasticity and it is approximately 2 nm thick (without noticeable dependence of the thickness on the grain size). Amorphous shear bands similar to ours have been previously observed in shock-loaded covalent ceramics (i.e., B 4 C and SiC) 35,36 . However, they were initiated either along certain crystallographic planes (B 4 C) or by planar faults (SiC) and, without exception, they provided the dominant mode of brittle fracture 37–39 .…”

Section: Resultssupporting

confidence: 88%

Plasticity without dislocations in a polycrystalline intermetallic

et al. 2019

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Dislocation activity is critical to ductility and the mechanical strength of metals. Dislocations are the primary drivers of plastic deformation, and their interactions with each other and with other microstructural features such as grain boundaries (GBs) lead to strengthening of metals. In general, suppressing dislocation activity leads to brittleness of polycrystalline materials. Here, we find an intermetallic that can accommodate large plastic strain without the help of dislocations. For small grain sizes, the primary deformation mechanism is GB sliding, whereas for larger grain sizes the material deforms by direct amorphization along shear planes. The unusual deformation mechanisms lead to the absence of traditional Hall-Petch (HP) relation commonly observed in metals and to an extended regime of strength weakening with grain refinement, referred to as the inverse HP relation. The results are first predicted in simulations and then confirmed experimentally.

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Section: Resultssupporting

confidence: 88%

Plasticity without dislocations in a polycrystalline intermetallic

et al. 2019

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“…For different materials (e.g., organic α-HMX crystal, Si, SiC, and SmCo 5 ) plastic deformation in shock or dynamic loading occurs by generation and motion of dislocations or twin boundaries up to some pressure or strain rate and via formation of amorphous shear nanobands at higher pressure or strain rate [145,180,318,[469][470][471][472]. This amorphization may occur via VM, like pressure-induced amorphization in [249].…”

Section: Virtual Melting As a New Mechanism Of Plastic Deformation And Stress Relaxation Under High Strain Rate Loadingmentioning

confidence: 99%

Phase transformations, fracture, and other structural changes in inelastic materials

Levitas

2021

International Journal of Plasticity

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“…8 Certain SiC defects have sharp optical and spin transitions, 15 and therefore defect engineering is applied to explore and fabricate high performance SiC devices. [15][16][17] Amorphization of SiC takes place under laser shock, 18 electron beam irradiation 19 and deformation. 4,9 Stacking faults serve as a precursor of amorphization.…”

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confidence: 99%

Ultrahigh Recovery of Fracture Strength on Mismatched Fractured Amorphous Surfaces of Silicon Carbide

et al. 2019

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Nanowires (NWs) have been envisioned as building blocks of nanotechnology and nanodevices. In this study, NWs were manipulated using a weasel hair, and fixed by conductive silver epoxy, eliminating the contaminations and damages induced by conventional beam depositions. The fracture strength of the amorphous silicon carbide was found to be 8.8 GPa, which was measured by in situ transmission electron microscopy nanomechanical testing, approaching the theoretical fracture limit. Here, we report that self-healing of mismatched fractured amorphous surfaces of brittle NWs was discovered. The fracture strength was found to be 5.6 GPa on the mismatched fractured surfaces, recovering 63.6% of that of pristine NWs. This is an ultrahigh recovery, due to the limits of reconstruction of dangling bonds on the fractured amorphous surfaces and the mismatched areas. Simulation by molecular dynamics showed fracture strength recovery of 65.9% on the mismatched fractured amorphous surfaces, which is in good agreement with the experimental results. Healing on the mismatched fractured amorphous surfaces is by reorganization of Si-C bonds forming Si-C and Si-Si bonds. The potential energy increases 2.6 eV in the reorganized Si-C bonds, and decreases by 3.2 and 1.9 eV, respectively, in the formed Si-C and Si-2 Si bonds. These findings provide insights for the reliability, design and fabrication of high performance NW-based devices, to avoid catastrophic failure working in harsh and extreme environments.

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Shock-induced amorphization in silicon carbide

Cited by 83 publications

References 30 publications

Plasticity without dislocations in a polycrystalline intermetallic

Plasticity without dislocations in a polycrystalline intermetallic

Phase transformations, fracture, and other structural changes in inelastic materials

Ultrahigh Recovery of Fracture Strength on Mismatched Fractured Amorphous Surfaces of Silicon Carbide

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