Deformation Twinning and Detwinning in Face‐Centered Cubic Metallic Materials

An, Xianghai; Ni, Song; Song, Min; Liao, Xiaozhou

doi:10.1002/adem.201900479

Cited by 31 publications

(19 citation statements)

References 91 publications

(268 reference statements)

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“…The blue circle in Figure 4 b shows a ledge occurring in the twin laminar crystal in the strained nt-Cu film. It has been proposed that the ledge is formed by the accumulation of the dislocations on the twin-boundary [ 44 , 45 ]. Typically, those dislocations belong to type-I and type-II slip systems, which are discussed in the previous section.…”

Section: Resultsmentioning

confidence: 99%

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

et al. 2021

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Tensile tests were carried on the electroplated Cu films with various densities of twin grain boundary. With TEM images and a selected area diffraction pattern, nano-twinned structure can be observed and defined in the electroplated Cu films. The density of the nano-twin grain structure can be manipulated with the concentration of gelatin in the Cu-sulfate electrolyte solution. We found that the strength of the Cu films is highly related to the twin-boundary density. The Cu film with a greater twin-boundary density has a larger fracture strength than the Cu film with a lesser twin-boundary density. After tensile tests, necking phenomenon (about 20 μm) occurred in the fractured Cu films. Moreover, by focused ion beam (FIB) cross-sectional analysis, the de-twinning can be observed in the region where necking begins. Thus, we believe that the de-twinning of the nano-twinned structure initiates the plastic deformation of the nano-twinned Cu films. Furthermore, with the analysis of the TEM images on the nano-twinned structure in the necking region of the fractured Cu films, the de-twinning mechanism attributes to two processes: (1) the ledge formation by the engagement of the dislocations with the twin boundaries and (2) the collapse of the ledges with the opposite twin-boundaries. In conclusion, the plastic deformation of nano-twinned Cu films is governed by the de-twinning of the nano-twinned structure. Moreover, the fracture strength of the nano-twinned Cu films is proportional to the twin-boundaries density.

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Section: Resultsmentioning

confidence: 99%

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

et al. 2021

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“…It is well established that mechanical twinning and detwinning operate in nanocrystalline FCC metals [3][4][5]. The dislocation-twin interactions potentially responsible for each of those two phenomena have been analyzed in detail [6].…”

Section: Introductionmentioning

confidence: 99%

Direct monitoring of twinning/detwinning in a TWIP steel under reversed cyclic loading

D'Hondt

Doquet

Couzinié

2021

Materials Science and Engineering: A

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In situ tensile and reversed cyclic tests were run on a TWIP steel in a SEM, with High-Resolution Digital Image Correlation (HR-DIC) measurements of the plastic strain field in a few selected grains prone to twinning, with a spatial resolution between 150 and 250nm, or under an AFM, with measurements of surface steps height at emerging deformation twins. Evidences of detwinning upon load reversal, as well as quantitative data on twinning/detwinning/retwinning were obtained. Detwinning and retwinning, which often were only partial, in spite of a fully reversed loading, did not seem to start at the onset of stress reversal. It required a sufficient variation of the stress, close to the twinning stress (estimated as 400 to 475 MPa) in absolute value, so that a mechanical hysteresis of the local twinned fraction occurred. Primary and secondary twinning along the same plane, inducing axial plastic strains in opposite directions, also allowed some grains to accommodate reversed plastic strain. Under fixed stress amplitude (± 500 MPa), the twin fraction in all monitored grains saturated at values between 0.5 and 3.5%, from the 2 nd cycle, while under fixed plastic strain amplitude (± 0.5%), it increased in a ratchetting way during the whole cyclic hardening stage, reaching 0.5 to 5%. In both cases, however, the plastic strain amplitude accommodated by twinning/detwinning, which reached 0.35 -0.42% in some grains during the 1 st cycle, decreased down to less than 0.05% after 100 to 1000 cycles.

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“…It is well established that the strengthening of twin-structured metals results from dislocations intersecting with coherent twin boundaries (CTBs), which was confirmed by both molecular dynamics (MD) simulations and experimental investigations [1,5,6,[9][10][11][12]. In contrast, for the softening mechanism, in situ atomic-scale observations of the detwinning process have rarely been studied, especially for twinstructured nanocrystalline (NC) metals with grain sizes of 15 nm [3,9,10,[13][14][15][16]. In addition to dislocation-CTB intersection, several MD simulations and experiments have indicated that detwinning can also significantly affect the mechanical properties of twin-structured metals [7,10,11,17].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to dislocation-CTB intersection, several MD simulations and experiments have indicated that detwinning can also significantly affect the mechanical properties of twin-structured metals [7,10,11,17]. The atomicscale mechanism of detwinning is crucial, which may provide clues for designing twin-structured metals with high strength and excellent ductility [1,10,[16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

In situ atomistic mechanisms of detwinning in nanocrystalline AuAg alloy

Yang

Lü

et al. 2021

Sci. China Mater.

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Detwinning is an important plastic deformation mechanism that can significantly affect the mechanical properties of twin-structured metals. Although many detwinning mechanisms have been proposed for pure metals, it is unclear whether such a deformation model is valid for nanocrystalline alloys because of the lack of direct evidence. Here, the atomicscale detwinning deformation process of a nanocrystalline AuAg alloy with an average grain size of~15 nm was investigated in situ. The results show that there are three types of detwinning mechanisms in nanocrystalline AuAg alloys. The first type of detwinning results from grain boundary migration. The second type of detwinning occurs through combined layer-by-layer thinning and incoherent twin boundary migration. The last one occurs through incoherent twin boundary migration, which results from the collective motion of partial dislocations in an array.

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Deformation Twinning and Detwinning in Face‐Centered Cubic Metallic Materials

Cited by 31 publications

References 91 publications

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films

Direct monitoring of twinning/detwinning in a TWIP steel under reversed cyclic loading

In situ atomistic mechanisms of detwinning in nanocrystalline AuAg alloy

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