Crystallography and Crystal Defects

Kelly, Anthony; Knowles, Kevin M.

doi:10.1002/9781119961468

Cited by 270 publications

(203 citation statements)

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“…The above analysis shows that, like many other macroscopic observations, HRTEM and atomistic simulations agree with the shear-shuffle classical [6,11,35] and TM models [8,17,27,37]. For large pure steps, motion entails pure glide-shuffle, which is essentially a limiting form of TD motion.…”

Section: The Shear-shuffle Mechanismsupporting

confidence: 49%

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Interface structures and twinning mechanisms of twins in hexagonal metals

Gong

Hirth

Liu

et al. 2017

Materials Research Letters

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A controversy concerning the description of {1012} 1011 twinning, whether it is shear-shuffle or pure glide-shuffle or pure shuffle, has developed. There is disagreement about the interpretation of transmission electron microscopic observations, atomistic simulations and theories for twin growth. In this article, we highlight the atomic-level, characteristic, equilibrium and non-equilibrium boundaries and corresponding boundary defects associated with the threedimensional 'normal', 'forward' and 'lateral' propagation of {1012} growth/annealing and deformation twins. Although deformation twin boundaries (TBs) after recovery exhibit some similarity to growth/annealing TBs because of the plastic accommodation of stress fields, there are important distinctions among them. These distinctions distinguish among the mechanisms of twin growth and resolve the controversy. In addition, a new type of disconnection, a glide disclination, is described for twinning. Synchroshear, seldom considered, is shown to be a likely mechanism for {1012} twinning. IMPACT STATEMENTA controversy concerning {1012} 1011 twinning in hcp metals has developed. We present comprehensive understanding of interface structures and twinning mechanisms of {1012} growth/annealing and deformation twins at the atomic level. ARTICLE HISTORY

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Section: The Shear-shuffle Mechanismsupporting

confidence: 49%

“…Bilby and Crocker [34] later defined the shuffles necessary to complete a twinning transformation via TDs. See also the reviews in [35,36]: we refer to the models in [6,11,35,36] as the classical model. These are incorporated in the topological model (TM) as recently reviewed [8,17,27,37].…”

Section: Introductionmentioning

confidence: 99%

Interface structures and twinning mechanisms of twins in hexagonal metals

Gong

Hirth

Liu

et al. 2017

Materials Research Letters

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“…Supplementary Note 2 derives the key relation of this paper, encoding the relationship between the observed angular shift of a nanocrystal reflection (hkl) and the angle c between this set of lattice planes and the planes normal to the c axis growth direction. For the case of a hexagonal unit cell, the angle between two sets of planes indexed by Miller indices (h 1 ,k 1 ,l 1 ) and (h 2 ,k 2 ,l 2 ) is given by 45 :…”

Section: Methodsmentioning

confidence: 99%

Visualization of nanocrystal breathing modes at extreme strains

et al. 2015

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Nanoscale dimensions in materials lead to unique electronic and structural properties with applications ranging from site-specific drug delivery to anodes for lithium-ion batteries. These functional properties often involve large-amplitude strains and structural modifications, and thus require an understanding of the dynamics of these processes. Here we use femtosecond X-ray scattering techniques to visualize, in real time and with atomic-scale resolution, light-induced anisotropic strains in nanocrystal spheres and rods. Strains at the percent level are observed in CdS and CdSe samples, associated with a rapid expansion followed by contraction along the nanosphere or nanorod radial direction driven by a transient carrierinduced stress. These morphological changes occur simultaneously with the first steps in the melting transition on hundreds of femtosecond timescales. This work represents the first direct real-time probe of the dynamics of these large-amplitude strains and shape changes in few-nanometre-scale particles.

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“…Annealing twins are often seen in fcc metals as a result of cold working followed by annealing heat treatment [20]. However, the stability of fcc austenite grains with twin faults during the deformation process is yet not fully understood.…”

Section: Twinned Austenite Grainsmentioning

confidence: 99%

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

et al. 2012

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Uniaxial straining experiments were performed on a rolled and annealed Si-alloyed TRIP (transformation-induced plasticity) steel sheet in order to assess the role of its microstructure on the mechanical stability of austenite grains with respect to martensitic transformation. The transformation behavior of individual metastable austenite grains was studied both at the surface and inside the bulk of the material using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD) by deforming the samples to different strain levels up to about 20%. A comparison of XRD-and EBSD-results revealed that the retained austenite grains at the surface have a stronger tendency to transform than the austenite grains in the bulk of the material.The deformation-induced changes of individual austenite grains before and after straining were monitored with EBSD. Three different types of austenite grains can be distinguished that have different transformation behaviors: austenite grains at the grain boundaries between ferrite grains, twinned austenite grains, and embedded austenite grains that are completely surrounded by a single ferrite grain. It was found that twinned austenite grains and the austenite grains present at the grain boundaries between larger ferrite grains typically transform first, i.e. are less stable, in contrast to austenite grains that are completely embedded in a larger ferrite grain. In the latter case, straining leads to rotations of the harder austenite grain within the softer ferrite matrix before the austenite transforms into martensite. The analysis suggests that austenite grain rotation behavior is also a significant contributing factor for enhancement of the ductility.

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Crystallography and Crystal Defects

Cited by 270 publications

References 0 publications

Interface structures and twinning mechanisms of twins in hexagonal metals

Interface structures and twinning mechanisms of twins in hexagonal metals

Visualization of nanocrystal breathing modes at extreme strains

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

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