Static and in-situ high-resolution transmission electron microscopy investigations of the atomic structure and dynamics of massive transformation interfaces in a Ti-Al alloy

Howe, James M.; Reynolds, W. T.; Vasudevan, Vijay K.

doi:10.1007/s11661-002-0362-4

Cited by 68 publications

(67 citation statements)

References 39 publications

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“…The interfacial plane normal to Δg ( = g α − g β ), where g α and g β are low-index reciprocal vectors, will contain GMSs with a relatively high ratio (i.e.,~7.5%4~1.5%), as interfacial misfit in the plane is virtually in 2D, lying on the planes defined by g α and g β . This geometry has been observed by Howe et al, 27 who showed the association of faceted interfaces with denser NCS (equivalent to the term of GMS used here) when the OR is random. At the other extreme, an exact one-to-one matching or a CSL with small unit cell may form in 2D.…”

Section: Integrated Frameworksupporting

confidence: 75%

“…Such an interface is characterised by a one-dimensional commensurate structure. 27 Its association with a local energy minimum has also been confirmed with an energy calculation. 51 The IO+OR group contains numerous models.…”

Section: Links Between Modelsmentioning

confidence: 64%

“…These kinds of ledge-free interfaces are in the white zone within the L f circle in Figure 3. Faceted interfaces due to a massive phase transformation 27 are associated with a singularity in GMS pattern, but they are not singular with respect to the OR. These facets locate in the white zone in the M-square in Figure 3.…”

Section: Links Between Modelsmentioning

confidence: 99%

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Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Zhang

Dai

2016

npj Comput Mater

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Faceted interfaces are a typical key feature of the morphology of many microstructures generated from solid-state phase transformations. Interpretation, prediction and simulation of this faceted morphology remain a challenge, especially for systems where irrational orientation relationships (ORs) between two phases and irrational interface orientations (IOs) are preferred. In terms of structural singularities, this work suggests an integrated framework, which possibly encompasses all candidates of faceted interfaces. The structural singularities are identified from a matching pattern, a dislocation structure and/or a ledge structure. The resultant singular interfaces have discrete IOs, described with low-index g's (rational orientations) and/or Δg's (either rational or irrational orientations). Various existing models are grouped according to their determined results regarding the OR and IO, and the links between the models are clarified in the integrated framework. Elimination of defect types as far as possible in a dominant singular interface often exerts a central restriction on the OR. An irrational IO is usually due to the elimination of dislocations in one direction, i.e., an O-line interface. Analytical methods using both three-dimensional and two-dimensional models for quantitative determinations of O-line interfaces are reviewed, and a detailed example showing the calculation for an irrational interface is given. The association between structural singularities and local energy minima is verified by atomistic calculations of interfacial energies in fcc/bcc alloys where it is found that the calculated equilibrium cross-sections are in a good agreement with observations from selected alloys.

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Section: Integrated Frameworksupporting

confidence: 75%

Section: Links Between Modelsmentioning

confidence: 64%

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Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Zhang

Dai

2016

npj Comput Mater

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“…In future, we expect that experimental research on solidsolid transformations will maintain a primary focus on the results of ultra-high-resolution techniques that yield both structural and chemical information [396]. The simulation of these transformations will increasingly involve advanced computationally intensive techniques, such as molecular dynamics [397], phase-field calculations [375], multiscale models [109] and the recently developed phase-field-crystal methods [152].…”

Section: Outlook: Solid-state Transformation Parallelsmentioning

confidence: 99%

Solidification microstructures and solid-state parallels: Recent developments, future directions

et al. 2009

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Rapid advances in atomistic and phase-field modeling techniques as well as new experiments have led to major progress in solidification science during the first years of this century. Here we review the most important findings in this technologically important area that impact our quantitative understanding of: (i) key anisotropic properties of the solid-liquid interface that govern solidification pattern evolution, including the solid-liquid interface free energy and the kinetic coefficient; (ii) dendritic solidification at small and large growth rates, with particular emphasis on orientation selection; (iii) regular and irregular eutectic and peritectic microstructures; (iv) effects of convection on microstructure formation; (v) solidification at a high volume fraction of solid and the related formation of pores and hot cracks; and (vi) solid-state transformations as far as they relate to solidification models and techniques. In light of this progress, critical issues that point to directions for future research in both solidification and solid-state transformations are identified.

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“…Although a general insight into the kinetics of these diffusional phase transformations has been developed, observations on the actual atomic processes taking place at the interface during the transformation are still very scarce. 2,3 The insight in the nature of martenstic transformations is even more limited than for diffusional transformations. The definition of a martensitic transformation is based on the characteristics of the atomic processes, viz.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulation of interface dynamics during the fcc-bcc transformation of a martensitic nature

2006

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The structural and dynamic properties of the interface during the fcc-bcc transformation in pure iron have been investigated by molecular dynamics simulations. An embedded atom method potential was used for the atomic interactions. Two interfaces, close to the Bain and Kurdjumov-Sachs orientation relations, have been examined during the fcc-to-bcc transformation. In each simulation the system was left to evolve freely at the imposed temperature. In a system with fully periodic boundaries no interface motion has been observed, whereas systems with at least one free boundary do show a mobile interface. After an incubation time, there is a very fast transformation from fcc to bcc, with interface velocities reaching values in the range of 200-700 m / s, depending on the interface orientation and on temperature. The characteristics of the transformation are of a martensitic nature, without this being imposed on the system. During the incubation time a complex interface structure is formed, which appears to be essential for the martensitic transformation. From the atomic displacements during the transformation, the occurrence of slip planes can be identified.

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Static and in-situ high-resolution transmission electron microscopy investigations of the atomic structure and dynamics of massive transformation interfaces in a Ti-Al alloy

Cited by 68 publications

References 39 publications

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Solidification microstructures and solid-state parallels: Recent developments, future directions

Molecular dynamics simulation of interface dynamics during the fcc-bcc transformation of a martensitic nature

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