Hierarchical twinning governed by defective twin boundary in metallic materials

Zhu, Qi; Huang, Qishan; Tian, Yanzhong; Zhao, Shuchun; Chen, Yingbin; Cao, Guang; Song, Kexing; Zhou, Yanjun; Yang, Wei; Zhang, Ze; An, Xianghai; Zhou, Haofei; Wang, Jiangwei

doi:10.1126/sciadv.abn8299

Cited by 47 publications

(19 citation statements)

References 51 publications

(82 reference statements)

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“…A 3-fold twin could directly develop into a FFT through Σ27 GB decomposition, while partial dislocation slipping is needed to be activated to cooperate with Σ9 GB decomposition causing the transition from a 2-fold twin to a FFT. The experimental observations of transformation from 2- and 2-order twins to a 5-fold twin in this study are energetically favorable …”

supporting

confidence: 48%

In Situ Atomic-Scale Observation of 5-Fold Twin Formation in Nanoscale Crystal under Mechanical Loading

et al. 2023

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A 5-fold twin is usually observed in nanostructured metals after mechanical tests and/or annealing treatment. However, the formation mechanism of a 5-fold twin has not been fully elaborated, due to the lack of direct time-resolved atomic-scale observation. Here, by using in situ nanomechanical testing combined with atomistic simulations, we show that sequential twinning slip in varying slip systems and decomposition of high-energy grain boundaries account for the 5-fold twin formation in a nanoscale gold single crystal under bending as well as the reversible formation and dissolution of a 5-fold twin in a nanocrystal with a preexisting twin under tension and shearing. Moreover, we find that the complex stress state in the neck area results in the breakdown of Schmid's law, causing 5-fold twin formation in a gold nanocrystal with a twin boundary parallel to the loading direction. These findings enrich our understanding of the formation process of high-order twin structures in nanostructured metals.

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supporting

confidence: 48%

In Situ Atomic-Scale Observation of 5-Fold Twin Formation in Nanoscale Crystal under Mechanical Loading

et al. 2023

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“…Interestingly, a secondary nanotwin T2 (delineated by blue dashed lines) is observed inside the primary twin T1. According to the atomistic dynamics of the self-activated hierarchical twinning behavior 25 , the emission of Shockley partial dislocations from the intrinsic kinks on the twin boundaries will occur when the kink height is greater than ve atomic layers, which in turn induces the nucleation and growth of secondary nanotwins. The unique twinning structure is also veri ed by the corresponding fast Fourier transform (FFT) (inset, Fig.…”

Section: Resultsmentioning

confidence: 99%

Vacancy-mediated anomalous phononic and electronic transport in defective half-Heusler ZrNiBi

Ren

Xue

Guo

et al. 2023

Preprint

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Studies of vacancy-mediated anomalous transport properties have flourished in diverse fields since they endow solid materials with fascinating photoelectric, ferroelectric, and spin-electric behaviors. Although phononic and electronic transport underpin the physical origin of thermoelectrics, vacancy has only played a stereotyped role as a scattering center. Here we reveal the multifunctionality of vacancy in tailoring the transport properties of an emerging thermoelectric material, defective n-type ZrNiBi. The phonon kinetic process is mediated in both propagating velocity and relaxation time: vacancy-induced local soft bonds lower the phonon velocity while acoustic-optical phonon coupling, anisotropic vibrations, and point-defect scattering induced by vacancy shorten the relaxation time. Consequently, defective ZrNiBi exhibits the lowest lattice thermal conductivity among the half-Heusler family. In addition, a vacancy-induced flat band features prominently in its electronic band structure, which is not only desirable for electron-sufficient thermoelectric materials but also interesting to drive other novel physical phenomena. Finally, better thermoelectric performance is established in a ZrNiBi-based compound. Our findings not only demonstrate a promising thermoelectric material but also promote the fascinating vacancy-mediated anomalous transport properties for multidisciplinary explorations.

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“…In addition, the direct proximity of the 9R structures to incoherent Σ3{112} boundaries indicates that they have nucleated from there and then grow along the direction parallel to the {111} coherent Σ3 boundary. This suggests that the formation of the 9R structures stems from the emission of partial dislocations from the incoherent Σ3 boundary under the thermal stresses imposed by water quenching [21,22,27] . Figure 3E and F show high-resolution HAADF-STEM images of the coherent twin boundary for the positions ~50 and ~20 nm away from the 9R structure, respectively.…”

Section: Resultsmentioning

confidence: 97%

“…The additional BA stacking around the coherent Σ3 boundary corresponds to one stacking fault or one unit of the HCP ε phase [1] . The presence of this additional HCP ε phase indicates that the phase transformation from the FCC γ to HCP ε phase at the coherent Σ3 boundary initiates from the 9R structure and its phase boundary, which is composed of an array of partial dislocations [21,22,27] .…”

Section: Resultsmentioning

confidence: 99%

Detwinning/twin growth-induced phase transformation in a metastable compositionally complex alloy

Lu¹,

An²,

Liebscher³

2022

Microstructures

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Extensive experiments have shown that the transformation from the face-centered cubic to hexagonal close-packed ε phase usually occurs around coherent Σ3 boundaries. However, in this letter, we reveal a different transformation mechanism in a metastable dual-phase compositionally complex alloy via a systematic high-resolution scanning transmission electron microscopy analysis. The face-centered cubic γ matrix can be transformed to the hexagonal close-packed ɛ phase (as small as one unit) around an incoherent Σ3 boundary (~30 nm), i.e., the facet of the coherent Σ3 boundary. This transformation is assisted by the detwinning/twin growth of a coherent Σ3 boundary during annealing treatment (900 °C for 60 min).

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Hierarchical twinning governed by defective twin boundary in metallic materials

Cited by 47 publications

References 51 publications

In Situ Atomic-Scale Observation of 5-Fold Twin Formation in Nanoscale Crystal under Mechanical Loading

In Situ Atomic-Scale Observation of 5-Fold Twin Formation in Nanoscale Crystal under Mechanical Loading

Vacancy-mediated anomalous phononic and electronic transport in defective half-Heusler ZrNiBi

Detwinning/twin growth-induced phase transformation in a metastable compositionally complex alloy

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